From 688e05b1f46d2f91b49aa31e5b9f4c8160be39a9 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Thu, 10 Apr 2025 07:48:01 +0000
Subject: [PATCH 01/19] add allocator libraries compatible with the new rustc
 mangling

---
 ffi/rs/BUILD.bazel                            | 34 ++++++++
 ffi/rs/allocator_library/BUILD.bazel          | 31 +++++++
 ffi/rs/allocator_library/allocator_library.rs | 82 +++++++++++++++++++
 ffi/rs/allocator_library/empty.rs             |  0
 rust/private/providers.bzl                    |  8 ++
 rust/private/rust.bzl                         | 32 +++++++-
 rust/private/rustc.bzl                        | 33 +++++++-
 rust/settings/BUILD.bazel                     |  3 +
 rust/settings/settings.bzl                    | 17 ++++
 rust/toolchain.bzl                            |  2 +
 .../.bazelrc                                  | 42 ++++++++++
 .../.gitignore                                |  2 +
 .../BUILD.bazel                               | 28 +++++++
 .../MODULE.bazel                              | 48 +++++++++++
 .../rustc_std_internal_symbol_mangling/dep.rs | 10 +++
 .../test.cc                                   |  7 ++
 .../test.rs                                   |  4 +
 util/process_wrapper/BUILD.bazel              |  2 +
 util/process_wrapper/BUILD.tinyjson.bazel     |  1 +
 19 files changed, 382 insertions(+), 4 deletions(-)
 create mode 100644 ffi/rs/BUILD.bazel
 create mode 100644 ffi/rs/allocator_library/BUILD.bazel
 create mode 100644 ffi/rs/allocator_library/allocator_library.rs
 create mode 100644 ffi/rs/allocator_library/empty.rs
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs

diff --git a/ffi/rs/BUILD.bazel b/ffi/rs/BUILD.bazel
new file mode 100644
index 0000000000..4124e7d750
--- /dev/null
+++ b/ffi/rs/BUILD.bazel
@@ -0,0 +1,34 @@
+load("@rules_rust//rust/private:rust.bzl", "rust_allocator_libraries")
+
+rust_allocator_libraries(
+    name = "allocator_libraries_with_mangling_support",
+    allocator_library = "@rules_rust//ffi/rs/allocator_library",
+    # FIXME: global_allocator_library
+    visibility = ["//visibility:public"],
+)
+
+rust_allocator_libraries(
+    name = "empty_allocator_libraries",
+    visibility = ["//visibility:public"],
+)
+
+alias(
+    name = "default_allocator_libraries",
+    actual = select({
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_on": ":allocator_libraries_with_mangling_support",
+        "//conditions:default": ":empty_allocator_libraries",
+    }),
+    visibility = ["//visibility:public"],
+)
+
+cc_library(
+    name = "empty",
+    visibility = ["//visibility:public"],
+)
+
+rust_allocator_libraries(
+    name = "allocator_libraries_with_mangling_support_without_process_wrapper",
+    allocator_library = "@rules_rust//ffi/rs/allocator_library:allocator_library_without_process_wrapper",
+    # FIXME: global_allocator_library
+    visibility = ["@rules_rust//util/process_wrapper:__subpackages__"],
+)
diff --git a/ffi/rs/allocator_library/BUILD.bazel b/ffi/rs/allocator_library/BUILD.bazel
new file mode 100644
index 0000000000..2c25418645
--- /dev/null
+++ b/ffi/rs/allocator_library/BUILD.bazel
@@ -0,0 +1,31 @@
+load("@rules_rust//rust:defs.bzl", "rust_library")
+load(
+    "@rules_rust//rust/private:rust.bzl",
+    "rust_library_without_process_wrapper",
+)
+
+package(
+    default_visibility = ["@rules_rust//ffi/rs:__subpackages__"],
+)
+
+srcs = select({
+    # Windows doesn't support weak symbol linkage.
+    # If someone can make this work on Windows, please do!
+    # For now we will silently not supply any symbols, because it would be very messy to conditionally define the default allocator library on toolchains depending on the platform.
+    "@platforms//os:windows": ["empty.rs"],
+    "//conditions:default": ["allocator_library.rs"],
+})
+
+rust_library(
+    name = "allocator_library",
+    srcs = srcs,
+    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    tags = ["manual"],
+)
+
+rust_library_without_process_wrapper(
+    name = "allocator_library_without_process_wrapper",
+    srcs = srcs,
+    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    tags = ["manual"],
+)
diff --git a/ffi/rs/allocator_library/allocator_library.rs b/ffi/rs/allocator_library/allocator_library.rs
new file mode 100644
index 0000000000..57ef91d69e
--- /dev/null
+++ b/ffi/rs/allocator_library/allocator_library.rs
@@ -0,0 +1,82 @@
+// Workaround for Rust issue https://github.com/rust-lang/rust/issues/73632
+// We provide the allocator functions that rustc leaves in rlibs. These are
+// normally provided by rustc during the linking phase (since the allocator in
+// use can vary), but if rustc doesn't do the final link we have to provide
+// these manually. Hopefully we can make progress on the above bug and
+// eventually not need this kludge.
+//
+// Recently rustc started mangling these symbols, so we rewrote them in
+// rust.
+// https://github.com/rust-lang/rust/pull/127173
+//
+// This code uses unstable internal rustc features that are only available when
+// using a nightly toolchain. Also, it is only compatible with versions
+// of rustc that include the symbol mangling, such as nightly/2025-04-08 or
+// later.
+#![no_std]
+#![allow(warnings)]
+#![allow(internal_features)]
+#![feature(rustc_attrs)]
+#![feature(linkage)]
+
+extern "C" {
+    #[rustc_std_internal_symbol]
+    fn __rdl_alloc(size: usize, align: usize) -> *mut u8;
+
+    #[rustc_std_internal_symbol]
+    fn __rdl_dealloc(ptr: *mut u8, size: usize, align: usize);
+
+    #[rustc_std_internal_symbol]
+    fn __rdl_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8;
+
+    #[rustc_std_internal_symbol]
+    fn __rdl_alloc_zeroed(size: usize, align: usize) -> *mut u8;
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_alloc(size: usize, align: usize) -> *mut u8 {
+    unsafe {
+        return __rdl_alloc(size, align);
+    }
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_dealloc(ptr: *mut u8, size: usize, align: usize) {
+    unsafe {
+        return __rdl_dealloc(ptr, size, align);
+    }
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_realloc(ptr: *mut u8, old_size: usize, align: usize, new_size: usize) -> *mut u8 {
+    unsafe {
+        return __rdl_realloc(ptr, old_size, align, new_size);
+    }
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_alloc_zeroed(size: usize, align: usize) -> *mut u8 {
+    unsafe {
+        return __rdl_alloc_zeroed(size, align);
+    }
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_alloc_error_handler(size: usize, align: usize) {
+    panic!();
+}
+
+// This symbol is normally emitted by rustc. 0 means OOMs should abort, 1 means OOMs should panic.
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+static mut __rust_alloc_error_handler_should_panic: u8 = 1;
+
+// See https://github.com/rust-lang/rust/issues/73632#issuecomment-1563462239
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+static mut __rust_no_alloc_shim_is_unstable: u8 = 0;
diff --git a/ffi/rs/allocator_library/empty.rs b/ffi/rs/allocator_library/empty.rs
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/rust/private/providers.bzl b/rust/private/providers.bzl
index 746370bc70..0ce4069ade 100644
--- a/rust/private/providers.bzl
+++ b/rust/private/providers.bzl
@@ -188,3 +188,11 @@ LintsInfo = provider(
         "rustdoc_lint_flags": "List[String]: rustc flags to specify when building rust_doc targets.",
     },
 )
+
+AllocatorLibrariesInfo = provider(
+    doc = "AllocatorLibrariesInfo provides allocator libraries for linking rust code with a non-rust linker.",
+    fields = {
+        "allocator_library": "Optional[CcInfo]: used when the default rust allocator is used",
+        "global_allocator_library": "Optional[CcInfo]: used when a global rust allocator is used",
+    },
+)
diff --git a/rust/private/rust.bzl b/rust/private/rust.bzl
index 74d458eef9..7112901672 100644
--- a/rust/private/rust.bzl
+++ b/rust/private/rust.bzl
@@ -17,7 +17,7 @@
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("//rust/private:common.bzl", "COMMON_PROVIDERS", "rust_common")
-load("//rust/private:providers.bzl", "BuildInfo", "LintsInfo")
+load("//rust/private:providers.bzl", "AllocatorLibrariesInfo", "BuildInfo", "LintsInfo")
 load("//rust/private:rustc.bzl", "rustc_compile_action")
 load(
     "//rust/private:utils.bzl",
@@ -719,6 +719,10 @@ _common_attrs = {
         doc = "A version to inject in the cargo environment variable.",
         default = "0.0.0",
     ),
+    "allocator_libraries": attr.label(
+        default = "//ffi/rs:default_allocator_libraries",
+        providers = [AllocatorLibrariesInfo],
+    ),
     "_stamp_flag": attr.label(
         doc = "A setting used to determine whether or not the `--stamp` flag is enabled",
         default = Label("//rust/private:stamp"),
@@ -1573,6 +1577,32 @@ rust_library_group = rule(
     """),
 )
 
+def _rust_allocator_libraries_impl(ctx):
+    allocator_library = ctx.attr.allocator_library[CcInfo] if ctx.attr.allocator_library else None
+    global_allocator_library = ctx.attr.global_allocator_library[CcInfo] if ctx.attr.global_allocator_library else None
+
+    providers = [AllocatorLibrariesInfo(
+        allocator_library = allocator_library,
+        global_allocator_library = global_allocator_library,
+    )]
+
+    return providers
+
+rust_allocator_libraries = rule(
+    implementation = _rust_allocator_libraries_impl,
+    provides = [AllocatorLibrariesInfo],
+    attrs = {
+        "allocator_library": attr.label(
+            doc = "An optional library to provide when a default rust allocator is used.",
+            providers = [CcInfo],
+        ),
+        "global_allocator_library": attr.label(
+            doc = "An optional library to provide when a default rust allocator is used.",
+            providers = [CcInfo],
+        ),
+    },
+)
+
 def _replace_illlegal_chars(name):
     """Replaces illegal characters in a name with underscores.
 
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index d78c28902c..525cf7ed42 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -27,7 +27,7 @@ load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load(":common.bzl", "rust_common")
 load(":compat.bzl", "abs")
 load(":lto.bzl", "construct_lto_arguments")
-load(":providers.bzl", "LintsInfo", "RustcOutputDiagnosticsInfo", _BuildInfo = "BuildInfo")
+load(":providers.bzl", "AllocatorLibrariesInfo", "LintsInfo", "RustcOutputDiagnosticsInfo", _BuildInfo = "BuildInfo")
 load(":rustc_resource_set.bzl", "get_rustc_resource_set", "is_codegen_units_enabled")
 load(":stamp.bzl", "is_stamping_enabled")
 load(
@@ -1604,16 +1604,43 @@ def _is_no_std(ctx, toolchain, crate_info):
         return False
     return True
 
+def _merge_attr_and_toolchain_alloc_info(attr_alloc_cc_info, toolchain_alloc_cc_info):
+    if not attr_alloc_cc_info:
+        fail("empty attr_alloc_cc_info")
+    return cc_common.merge_cc_infos(cc_infos = [attr_alloc_cc_info, toolchain_alloc_cc_info])
+
 def _get_std_and_alloc_info(ctx, toolchain, crate_info):
+    # Handles standard libraries and allocator shims.
+    #
+    # The standard libraries vary between "std" and "nostd" flavors.
+    #
+    # The allocator libraries vary along two dimensions:
+    # * the type of rust allocator used (default or global)
+    # * the mechanism providing the libraries (via the rust rules
+    #   allocator_libraries attribute, or via the rust toolchain allocator
+    #   attributes).
+    #
+    # When provided, the allocator_libraries attribute takes precedence over the
+    # toolchain allocator attributes.
+    attr_alloc_libs = None
+    if hasattr(ctx.attr, "allocator_libraries"):
+        attr_alloc_libs = ctx.attr.allocator_libraries[AllocatorLibrariesInfo]
     if is_exec_configuration(ctx):
+        if attr_alloc_libs.allocator_library:
+            return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.allocator_library, toolchain.libstd_no_allocator_ccinfo)
         return toolchain.libstd_and_allocator_ccinfo
     if toolchain._experimental_use_global_allocator:
         if _is_no_std(ctx, toolchain, crate_info):
+            if attr_alloc_libs.global_allocator_library:
+                return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.global_allocator_library, toolchain.nostd_no_allocator_ccinfo)
             return toolchain.nostd_and_global_allocator_cc_info
         else:
+            if attr_alloc_libs.global_allocator_library:
+                return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.global_allocator_library, toolchain.libstd_no_allocator_ccinfo)
             return toolchain.libstd_and_global_allocator_ccinfo
-    else:
-        return toolchain.libstd_and_allocator_ccinfo
+    if attr_alloc_libs.allocator_library:
+        return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.allocator_library, toolchain.libstd_no_allocator_ccinfo)
+    return toolchain.libstd_and_allocator_ccinfo
 
 def _is_dylib(dep):
     return not bool(dep.static_library or dep.pic_static_library)
diff --git a/rust/settings/BUILD.bazel b/rust/settings/BUILD.bazel
index 8fb46461d8..8774b00fdb 100644
--- a/rust/settings/BUILD.bazel
+++ b/rust/settings/BUILD.bazel
@@ -9,6 +9,7 @@ load(
     "error_format",
     "experimental_link_std_dylib",
     "experimental_per_crate_rustc_flag",
+    "experimental_use_allocator_libraries_with_mangled_symbols",
     "experimental_use_cc_common_link",
     "experimental_use_coverage_metadata_files",
     "experimental_use_global_allocator",
@@ -71,6 +72,8 @@ experimental_use_coverage_metadata_files()
 
 experimental_use_global_allocator()
 
+experimental_use_allocator_libraries_with_mangled_symbols()
+
 experimental_use_sh_toolchain_for_bootstrap_process_wrapper()
 
 extra_exec_rustc_flag()
diff --git a/rust/settings/settings.bzl b/rust/settings/settings.bzl
index 1444600d2d..ef830a7384 100644
--- a/rust/settings/settings.bzl
+++ b/rust/settings/settings.bzl
@@ -125,6 +125,23 @@ def experimental_use_global_allocator():
         build_setting_default = False,
     )
 
+def experimental_use_allocator_libraries_with_mangled_symbols():
+    """A flag used to select allocator libraries implemented in rust that are compatible with rustc's symbol mangling.
+
+    This currently requires nightly rustc from 2025-04-05 or later.
+    """
+    bool_flag(
+        name = "experimental_use_allocator_libraries_with_mangled_symbols",
+        build_setting_default = False,
+    )
+
+    native.config_setting(
+        name = "experimental_use_allocator_libraries_with_mangled_symbols_on",
+        flag_values = {
+            ":experimental_use_allocator_libraries_with_mangled_symbols": "true",
+        },
+    )
+
 def experimental_use_coverage_metadata_files():
     """A flag to have coverage tooling added as `coverage_common.instrumented_files_info.metadata_files` instead of \
     reporting tools like `llvm-cov` and `llvm-profdata` as runfiles to each test.
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index 91bc5455e9..7171803bf5 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -672,6 +672,8 @@ def _rust_toolchain_impl(ctx):
         libstd_and_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.allocator_library, "std"),
         libstd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "std"),
         nostd_and_global_allocator_cc_info = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "no_std_with_alloc"),
+        libstd_no_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "std"),
+        nostd_no_allocator_cc_info = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "no_std_with_alloc"),
         llvm_cov = ctx.file.llvm_cov,
         llvm_profdata = ctx.file.llvm_profdata,
         lto = lto,
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
new file mode 100644
index 0000000000..44bf1ed56c
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
@@ -0,0 +1,42 @@
+###############################################################################
+## Bazel Configuration Flags
+###############################################################################
+
+build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
+build --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
+
+###############################################################################
+
+# Enable rustfmt for all targets in the workspace
+build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
+build:rustfmt --output_groups=+rustfmt_checks
+
+# Enable clippy for all targets in the workspace
+build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
+build:clippy --output_groups=+clippy_checks
+
+###############################################################################
+## Incompatibility flags
+###############################################################################
+
+# https://github.com/bazelbuild/bazel/issues/8195
+build --incompatible_disallow_empty_glob=true
+
+# https://github.com/bazelbuild/bazel/issues/12821
+build --nolegacy_external_runfiles
+
+# Required for cargo_build_script support before Bazel 7
+build --incompatible_merge_fixed_and_default_shell_env
+
+# https://github.com/bazelbuild/bazel/issues/23043.
+build --incompatible_autoload_externally=
+
+###############################################################################
+## Bzlmod
+###############################################################################
+
+# A configuration for disabling bzlmod.
+common:no-bzlmod --noenable_bzlmod --enable_workspace
+
+# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
+common --lockfile_mode=off
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
new file mode 100644
index 0000000000..2f0f755d60
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
@@ -0,0 +1,2 @@
+/bazel-*
+/MODULE.bazel.lock
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
new file mode 100644
index 0000000000..eaa2138bcc
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
@@ -0,0 +1,28 @@
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
+load(
+    "@rules_rust//rust:defs.bzl",
+    "rust_binary",
+    "rust_library",
+    "rust_shared_library",
+    "rust_test",
+)
+
+rust_library(
+    name = "rsdep",
+    srcs = ["dep.rs"],
+)
+
+rust_test(
+    name = "rstest",
+    srcs = ["test.rs"],
+    experimental_use_cc_common_link = 1,
+    deps = [
+        ":rsdep",
+    ],
+)
+
+cc_test(
+    name = "cctest",
+    srcs = ["test.cc"],
+    deps = [":rsdep"],
+)
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
new file mode 100644
index 0000000000..f019e43a62
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
@@ -0,0 +1,48 @@
+# Repository setup to validate rules_rust with rustc that mangles rustc_std_internal_symbols.
+#
+# To support linking rust code into non-rust contexts, we must provide
+# implementations of the default internal rust allocator symbols, e.g.:
+# https://github.com/bazelbuild/rules_rust/blob/main/ffi/cc/allocator_library/allocator_library.cc
+#
+# Recent versions of rustc started to mangle these internal symbols,
+# rendering our c++ implementations ineffective:
+# https://github.com/rust-lang/rust/pull/127173
+module(
+    name = "rules_rust_test_cc_common_link_rustc_std_internal_symbol_mangling",
+    version = "0.0.0",
+)
+
+bazel_dep(name = "rules_rust", version = "0.0.0")
+local_path_override(
+    module_name = "rules_rust",
+    path = "../../../..",
+)
+
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "platforms", version = "0.0.11")
+
+rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.toolchain(
+    versions = [VERSION],
+)
+rust.repository_set(
+    name = "rust_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    #global_allocator_library = "",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
+)
+use_repo(rust, "rust_toolchains")
+
+register_toolchains("@rust_toolchains//:all")
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
new file mode 100644
index 0000000000..3ed213f810
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
@@ -0,0 +1,10 @@
+#[no_mangle]
+pub extern "C" fn rdep() -> i32 {
+    let mut v = vec![1, 2, 3];
+    while v.len() < 1000 {
+        let n = v.len();
+        v.push(v[n-1] + v[n-2]);
+        v.push(v[n-3]);
+    }
+    return v.len().try_into().unwrap();
+}
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
new file mode 100644
index 0000000000..6974d968f9
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
@@ -0,0 +1,7 @@
+#include <cstdio>
+
+extern "C" int rdep();
+
+int main() {
+  printf("%d\n", rdep());
+}
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs
new file mode 100644
index 0000000000..7f433b89f7
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs
@@ -0,0 +1,4 @@
+#[test]
+fn test() {
+    assert_eq!(1001, rsdep::rdep());
+}
diff --git a/util/process_wrapper/BUILD.bazel b/util/process_wrapper/BUILD.bazel
index 4c4ce05706..53963db826 100644
--- a/util/process_wrapper/BUILD.bazel
+++ b/util/process_wrapper/BUILD.bazel
@@ -31,7 +31,9 @@ selects.config_setting_group(
 rust_binary_without_process_wrapper(
     name = "process_wrapper",
     srcs = glob(["*.rs"]),
+    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
     edition = "2018",
+    experimental_use_cc_common_link = 0,
     # To ensure the process wrapper is produced deterministically
     # debug info, which is known to sometimes have host specific
     # paths embedded in this section, is stripped out.
diff --git a/util/process_wrapper/BUILD.tinyjson.bazel b/util/process_wrapper/BUILD.tinyjson.bazel
index f8013f6efd..7a7bcb3367 100644
--- a/util/process_wrapper/BUILD.tinyjson.bazel
+++ b/util/process_wrapper/BUILD.tinyjson.bazel
@@ -4,6 +4,7 @@ load("@rules_rust//rust/private:rust.bzl", "rust_library_without_process_wrapper
 rust_library_without_process_wrapper(
     name = "tinyjson",
     srcs = glob(["src/*.rs"]),
+    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
     edition = "2018",
     # To ensure the process wrapper is produced deterministically
     # debug info, which is known to sometimes have host specific

From 97d65c669466d03827e1eb2c926be3534961f18d Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Thu, 10 Apr 2025 08:02:47 +0000
Subject: [PATCH 02/19] fixes

---
 ffi/rs/allocator_library/BUILD.bazel          |  2 ++
 ffi/rs/allocator_library/allocator_library.rs |  2 +-
 rust/private/rustc.bzl                        | 22 ++++++++++---------
 .../BUILD.bazel                               |  4 +---
 util/process_wrapper/BUILD.bazel              |  3 +--
 5 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/ffi/rs/allocator_library/BUILD.bazel b/ffi/rs/allocator_library/BUILD.bazel
index 2c25418645..ee02f97db4 100644
--- a/ffi/rs/allocator_library/BUILD.bazel
+++ b/ffi/rs/allocator_library/BUILD.bazel
@@ -20,6 +20,7 @@ rust_library(
     name = "allocator_library",
     srcs = srcs,
     allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    edition = "2024",
     tags = ["manual"],
 )
 
@@ -27,5 +28,6 @@ rust_library_without_process_wrapper(
     name = "allocator_library_without_process_wrapper",
     srcs = srcs,
     allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    edition = "2024",
     tags = ["manual"],
 )
diff --git a/ffi/rs/allocator_library/allocator_library.rs b/ffi/rs/allocator_library/allocator_library.rs
index 57ef91d69e..b332b247ef 100644
--- a/ffi/rs/allocator_library/allocator_library.rs
+++ b/ffi/rs/allocator_library/allocator_library.rs
@@ -19,7 +19,7 @@
 #![feature(rustc_attrs)]
 #![feature(linkage)]
 
-extern "C" {
+unsafe extern "C" {
     #[rustc_std_internal_symbol]
     fn __rdl_alloc(size: usize, align: usize) -> *mut u8;
 
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index 525cf7ed42..247fc98e2e 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -1622,24 +1622,26 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
     #
     # When provided, the allocator_libraries attribute takes precedence over the
     # toolchain allocator attributes.
-    attr_alloc_libs = None
+    attr_allocator_library = None
+    attr_global_allocator_library = None
     if hasattr(ctx.attr, "allocator_libraries"):
-        attr_alloc_libs = ctx.attr.allocator_libraries[AllocatorLibrariesInfo]
+        attr_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].allocator_library
+        attr_global_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].global_allocator_library
     if is_exec_configuration(ctx):
-        if attr_alloc_libs.allocator_library:
-            return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.allocator_library, toolchain.libstd_no_allocator_ccinfo)
+        if attr_allocator_library:
+            return _merge_attr_and_toolchain_alloc_info(attr_allocator_library, toolchain.libstd_no_allocator_ccinfo)
         return toolchain.libstd_and_allocator_ccinfo
     if toolchain._experimental_use_global_allocator:
         if _is_no_std(ctx, toolchain, crate_info):
-            if attr_alloc_libs.global_allocator_library:
-                return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.global_allocator_library, toolchain.nostd_no_allocator_ccinfo)
+            if attr_global_allocator_library:
+                return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.nostd_no_allocator_ccinfo)
             return toolchain.nostd_and_global_allocator_cc_info
         else:
-            if attr_alloc_libs.global_allocator_library:
-                return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.global_allocator_library, toolchain.libstd_no_allocator_ccinfo)
+            if attr_global_allocator_library:
+                return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.libstd_no_allocator_ccinfo)
             return toolchain.libstd_and_global_allocator_ccinfo
-    if attr_alloc_libs.allocator_library:
-        return _merge_attr_and_toolchain_alloc_info(attr_alloc_libs.allocator_library, toolchain.libstd_no_allocator_ccinfo)
+    if attr_allocator_library:
+        return _merge_attr_and_toolchain_alloc_info(attr_allocator_library, toolchain.libstd_no_allocator_ccinfo)
     return toolchain.libstd_and_allocator_ccinfo
 
 def _is_dylib(dep):
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
index eaa2138bcc..74fa11b7d8 100644
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
@@ -1,9 +1,7 @@
-load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
+load("@rules_cc//cc:defs.bzl", "cc_test")
 load(
     "@rules_rust//rust:defs.bzl",
-    "rust_binary",
     "rust_library",
-    "rust_shared_library",
     "rust_test",
 )
 
diff --git a/util/process_wrapper/BUILD.bazel b/util/process_wrapper/BUILD.bazel
index 53963db826..381680ed9e 100644
--- a/util/process_wrapper/BUILD.bazel
+++ b/util/process_wrapper/BUILD.bazel
@@ -31,9 +31,8 @@ selects.config_setting_group(
 rust_binary_without_process_wrapper(
     name = "process_wrapper",
     srcs = glob(["*.rs"]),
-    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    allocator_libraries = "@rules_rust//ffi/rs:allocator_libraries_with_mangling_support_without_process_wrapper",
     edition = "2018",
-    experimental_use_cc_common_link = 0,
     # To ensure the process wrapper is produced deterministically
     # debug info, which is known to sometimes have host specific
     # paths embedded in this section, is stripped out.

From 09ef05273b061d47f9c1fbe185d31bccfcb2150c Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Thu, 10 Apr 2025 10:01:29 +0000
Subject: [PATCH 03/19] fixes

---
 .../rustc_std_internal_symbol_mangling/WORKSPACE.bazel       | 1 +
 .../cc_common_link/rustc_std_internal_symbol_mangling/dep.rs | 5 ++++-
 .../rustc_std_internal_symbol_mangling/test.cc               | 5 ++++-
 util/process_wrapper/BUILD.bazel                             | 5 ++++-
 4 files changed, 13 insertions(+), 3 deletions(-)
 create mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel

diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
new file mode 100644
index 0000000000..c29b7e548f
--- /dev/null
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
@@ -0,0 +1 @@
+workspace(name = "rules_rust_test_cc_common_link_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
index 3ed213f810..c690c08b14 100644
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
@@ -1,10 +1,13 @@
 #[no_mangle]
 pub extern "C" fn rdep() -> i32 {
+    // Just some logic complicated enough to require heap
+    // allocations.
+    use std::convert::TryInto;
     let mut v = vec![1, 2, 3];
     while v.len() < 1000 {
         let n = v.len();
         v.push(v[n-1] + v[n-2]);
         v.push(v[n-3]);
     }
-    return v.len().try_into().unwrap();
+    return v.len().try_into().unwrap();  // returns 1001
 }
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
index 6974d968f9..0cf2e6b27a 100644
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
@@ -3,5 +3,8 @@
 extern "C" int rdep();
 
 int main() {
-  printf("%d\n", rdep());
+  if (rdep() != 1001) {
+    return 1;
+  }
+  return 0;
 }
diff --git a/util/process_wrapper/BUILD.bazel b/util/process_wrapper/BUILD.bazel
index 381680ed9e..a946776e41 100644
--- a/util/process_wrapper/BUILD.bazel
+++ b/util/process_wrapper/BUILD.bazel
@@ -31,7 +31,10 @@ selects.config_setting_group(
 rust_binary_without_process_wrapper(
     name = "process_wrapper",
     srcs = glob(["*.rs"]),
-    allocator_libraries = "@rules_rust//ffi/rs:allocator_libraries_with_mangling_support_without_process_wrapper",
+    allocator_libraries = select({
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_on": "@rules_rust//ffi/rs:allocator_libraries_with_mangling_support_without_process_wrapper",
+        "//conditions:default": "@rules_rust//ffi/rs:empty_allocator_libraries",
+    }),
     edition = "2018",
     # To ensure the process wrapper is produced deterministically
     # debug info, which is known to sometimes have host specific

From aef67c7f67eff6099d52492421f569290452ebdf Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Fri, 11 Apr 2025 10:00:39 +0000
Subject: [PATCH 04/19] add global alloc support and tests

---
 ffi/rs/BUILD.bazel                            |  7 ++-
 ffi/rs/allocator_library/allocator_library.rs |  4 ++
 ffi/rs/global_allocator_library/BUILD.bazel   | 25 ++++++++++
 ffi/rs/global_allocator_library/empty.rs      |  0
 .../global_allocator_library.rs               | 48 +++++++++++++++++++
 .../BUILD.bazel                               |  1 -
 .../.bazelrc                                  | 43 +++++++++++++++++
 .../BUILD.bazel                               | 17 +++++++
 .../MODULE.bazel                              | 37 ++++++++++++++
 .../WORKSPACE.bazel                           |  1 +
 .../bazel-bin                                 |  1 +
 .../bazel-out                                 |  1 +
 .../bazel-rustc_std_internal_symbol_mangling  |  1 +
 .../bazel-testlogs                            |  1 +
 .../main.rs                                   | 46 ++++++++++++++++++
 15 files changed, 230 insertions(+), 3 deletions(-)
 create mode 100644 ffi/rs/global_allocator_library/BUILD.bazel
 create mode 100644 ffi/rs/global_allocator_library/empty.rs
 create mode 100644 ffi/rs/global_allocator_library/global_allocator_library.rs
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
 create mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
 create mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
 create mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
 create mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs

diff --git a/ffi/rs/BUILD.bazel b/ffi/rs/BUILD.bazel
index 4124e7d750..dd5e8f0f86 100644
--- a/ffi/rs/BUILD.bazel
+++ b/ffi/rs/BUILD.bazel
@@ -3,7 +3,7 @@ load("@rules_rust//rust/private:rust.bzl", "rust_allocator_libraries")
 rust_allocator_libraries(
     name = "allocator_libraries_with_mangling_support",
     allocator_library = "@rules_rust//ffi/rs/allocator_library",
-    # FIXME: global_allocator_library
+    global_allocator_library = "@rules_rust//ffi/rs/global_allocator_library",
     visibility = ["//visibility:public"],
 )
 
@@ -26,9 +26,12 @@ cc_library(
     visibility = ["//visibility:public"],
 )
 
+# Allocator libraries used while bootstrapping the process wrapper.
 rust_allocator_libraries(
     name = "allocator_libraries_with_mangling_support_without_process_wrapper",
     allocator_library = "@rules_rust//ffi/rs/allocator_library:allocator_library_without_process_wrapper",
-    # FIXME: global_allocator_library
+    # no need for a global allocator library, since the process wrapper
+    # is always bootstrapped in exec mode, which always uses the default
+    # allocator.
     visibility = ["@rules_rust//util/process_wrapper:__subpackages__"],
 )
diff --git a/ffi/rs/allocator_library/allocator_library.rs b/ffi/rs/allocator_library/allocator_library.rs
index b332b247ef..fb498d81d7 100644
--- a/ffi/rs/allocator_library/allocator_library.rs
+++ b/ffi/rs/allocator_library/allocator_library.rs
@@ -13,6 +13,9 @@
 // using a nightly toolchain. Also, it is only compatible with versions
 // of rustc that include the symbol mangling, such as nightly/2025-04-08 or
 // later.
+//
+// This has been translated from our c++ version
+// rules_rust/ffi/cc/allocator_library/allocator_library.cc.
 #![no_std]
 #![allow(warnings)]
 #![allow(internal_features)]
@@ -71,6 +74,7 @@ fn __rust_alloc_error_handler(size: usize, align: usize) {
     panic!();
 }
 
+// New feature as of https://github.com/rust-lang/rust/pull/88098.
 // This symbol is normally emitted by rustc. 0 means OOMs should abort, 1 means OOMs should panic.
 #[linkage = "weak"]
 #[rustc_std_internal_symbol]
diff --git a/ffi/rs/global_allocator_library/BUILD.bazel b/ffi/rs/global_allocator_library/BUILD.bazel
new file mode 100644
index 0000000000..adbe884396
--- /dev/null
+++ b/ffi/rs/global_allocator_library/BUILD.bazel
@@ -0,0 +1,25 @@
+load("@rules_rust//rust:defs.bzl", "rust_library")
+load(
+    "@rules_rust//rust/private:rust.bzl",
+    "rust_library_without_process_wrapper",
+)
+
+package(
+    default_visibility = ["@rules_rust//ffi/rs:__subpackages__"],
+)
+
+srcs = select({
+    # Windows doesn't support weak symbol linkage.
+    # If someone can make this work on Windows, please do!
+    # For now we will silently not supply any symbols, because it would be very messy to conditionally define the global allocator library on toolchains depending on the platform.
+    "@platforms//os:windows": ["empty.rs"],
+    "//conditions:default": ["global_allocator_library.rs"],
+})
+
+rust_library(
+    name = "global_allocator_library",
+    srcs = srcs,
+    allocator_libraries = "@rules_rust//ffi/rs:empty_allocator_libraries",
+    edition = "2024",
+    tags = ["manual"],
+)
diff --git a/ffi/rs/global_allocator_library/empty.rs b/ffi/rs/global_allocator_library/empty.rs
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/ffi/rs/global_allocator_library/global_allocator_library.rs b/ffi/rs/global_allocator_library/global_allocator_library.rs
new file mode 100644
index 0000000000..44dbe88ea3
--- /dev/null
+++ b/ffi/rs/global_allocator_library/global_allocator_library.rs
@@ -0,0 +1,48 @@
+// Workaround for Rust issue https://github.com/rust-lang/rust/issues/73632
+// We provide the allocator functions that rustc leaves in rlibs. These are
+// normally provided by rustc during the linking phase (since the allocator in
+// use can vary), but if rustc doesn't do the final link we have to provide
+// these manually. Hopefully we can make progress on the above bug and
+// eventually not need this kludge.
+//
+// Recently rustc started mangling these symbols, so we rewrote them in
+// rust.
+// https://github.com/rust-lang/rust/pull/127173
+//
+// This code uses unstable internal rustc features that are only available when
+// using a nightly toolchain. Also, it is only compatible with versions
+// of rustc that include the symbol mangling, such as nightly/2025-04-08 or
+// later.
+//
+// This has been translated from our c++ version
+// rules_rust/ffi/cc/global_allocator_library/global_allocator_library.cc.
+#![no_std]
+#![allow(warnings)]
+#![allow(internal_features)]
+#![feature(rustc_attrs)]
+#![feature(linkage)]
+
+unsafe extern "C" {
+    #[rustc_std_internal_symbol]
+    fn __rg_oom(size: usize, align: usize) -> *mut u8;
+}
+
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+fn __rust_alloc_error_handler(size: usize, align: usize) {
+    unsafe {
+        __rg_oom(size, align);
+    }
+}
+
+
+// New feature as of https://github.com/rust-lang/rust/pull/88098.
+// This symbol is normally emitted by rustc. 0 means OOMs should abort, 1 means OOMs should panic.
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+static mut __rust_alloc_error_handler_should_panic: u8 = 1;
+
+// See https://github.com/rust-lang/rust/issues/73632#issuecomment-1563462239
+#[linkage = "weak"]
+#[rustc_std_internal_symbol]
+static mut __rust_no_alloc_shim_is_unstable: u8 = 0;
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
index 74fa11b7d8..6bcad908eb 100644
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
@@ -13,7 +13,6 @@ rust_library(
 rust_test(
     name = "rstest",
     srcs = ["test.rs"],
-    experimental_use_cc_common_link = 1,
     deps = [
         ":rsdep",
     ],
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
new file mode 100644
index 0000000000..a09e927526
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
@@ -0,0 +1,43 @@
+###############################################################################
+## Bazel Configuration Flags
+###############################################################################
+
+build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
+build --@rules_rust//rust/settings:experimental_use_global_allocator=True
+build --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
+
+###############################################################################
+
+# Enable rustfmt for all targets in the workspace
+build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
+build:rustfmt --output_groups=+rustfmt_checks
+
+# Enable clippy for all targets in the workspace
+build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
+build:clippy --output_groups=+clippy_checks
+
+###############################################################################
+## Incompatibility flags
+###############################################################################
+
+# https://github.com/bazelbuild/bazel/issues/8195
+build --incompatible_disallow_empty_glob=true
+
+# https://github.com/bazelbuild/bazel/issues/12821
+build --nolegacy_external_runfiles
+
+# Required for cargo_build_script support before Bazel 7
+build --incompatible_merge_fixed_and_default_shell_env
+
+# https://github.com/bazelbuild/bazel/issues/23043.
+build --incompatible_autoload_externally=
+
+###############################################################################
+## Bzlmod
+###############################################################################
+
+# A configuration for disabling bzlmod.
+common:no-bzlmod --noenable_bzlmod --enable_workspace
+
+# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
+common --lockfile_mode=off
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
new file mode 100644
index 0000000000..d037a22e52
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
@@ -0,0 +1,17 @@
+load(
+    "@rules_rust//rust:defs.bzl",
+    "rust_binary",
+    "rust_test",
+)
+
+rust_binary(
+    name = "main",
+    srcs = ["main.rs"],
+    edition = "2021",
+)
+
+rust_test(
+    name = "global_alloc_test",
+    crate = ":main",
+    edition = "2021",
+)
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
new file mode 100644
index 0000000000..330e590007
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
@@ -0,0 +1,37 @@
+module(
+    name = "rules_rust_test_cc_common_link_with_global_alloc_rustc_std_internal_symbol_mangling",
+    version = "0.0.0",
+)
+
+bazel_dep(name = "rules_rust", version = "0.0.0")
+local_path_override(
+    module_name = "rules_rust",
+    path = "../../../..",
+)
+
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "platforms", version = "0.0.11")
+
+rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.toolchain(
+    versions = [VERSION],
+)
+rust.repository_set(
+    name = "rust_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
+)
+use_repo(rust, "rust_toolchains")
+
+register_toolchains("@rust_toolchains//:all")
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
new file mode 100644
index 0000000000..571df760ab
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
@@ -0,0 +1 @@
+workspace(name = "rules_rust_test_cc_common_link_with_global_alloc_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
new file mode 120000
index 0000000000..c4a512a4ab
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
@@ -0,0 +1 @@
+/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out/k8-fastbuild/bin
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
new file mode 120000
index 0000000000..26d54958ed
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
@@ -0,0 +1 @@
+/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
new file mode 120000
index 0000000000..276d865d02
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
@@ -0,0 +1 @@
+/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
new file mode 120000
index 0000000000..ba4f7a6077
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
@@ -0,0 +1 @@
+/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out/k8-fastbuild/testlogs
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs
new file mode 100644
index 0000000000..79dccff40f
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs
@@ -0,0 +1,46 @@
+use std::alloc::{GlobalAlloc, Layout, System};
+use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
+
+static ALLOCATED: AtomicUsize = AtomicUsize::new(0);
+
+struct MyAllocator;
+
+unsafe impl GlobalAlloc for MyAllocator {
+    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
+        let ret = System.alloc(layout);
+        if !ret.is_null() {
+            ALLOCATED.fetch_add(layout.size(), SeqCst);
+        }
+        ret
+    }
+
+    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
+        System.dealloc(ptr, layout);
+        ALLOCATED.fetch_sub(layout.size(), SeqCst);
+    }
+}
+
+#[global_allocator]
+static GLOBAL: MyAllocator = MyAllocator;
+
+fn main() {
+    println!("allocated bytes before main: {}", ALLOCATED.load(SeqCst));
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_global_alloc_was_used() {
+        // Allocated bytes before main
+        let bytes_start = ALLOCATED.load(SeqCst);
+
+        let _x = Box::new(5); // 4 bytes
+        let _y = Box::new(true); // 1 byte
+
+        let bytes_end = ALLOCATED.load(SeqCst);
+
+        assert_eq!(bytes_end - bytes_start, 5);
+    }
+}

From 2c20ec442654523356e051e5b1b12faae65b742d Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 15 Apr 2025 14:10:14 +0000
Subject: [PATCH 05/19] add a way to control rustc allocator libraries feature
 per-toolchain

---
 ffi/rs/BUILD.bazel                          |  3 +++
 ffi/rs/allocator_library/BUILD.bazel        |  2 ++
 ffi/rs/global_allocator_library/BUILD.bazel |  4 ----
 rust/private/rust.bzl                       | 11 ++++++----
 rust/private/rustc.bzl                      | 10 ++++++++-
 rust/settings/BUILD.bazel                   |  4 +++-
 rust/settings/settings.bzl                  |  8 ++++---
 rust/toolchain.bzl                          | 23 +++++++++++++++++++++
 8 files changed, 52 insertions(+), 13 deletions(-)

diff --git a/ffi/rs/BUILD.bazel b/ffi/rs/BUILD.bazel
index dd5e8f0f86..1fb2abebec 100644
--- a/ffi/rs/BUILD.bazel
+++ b/ffi/rs/BUILD.bazel
@@ -1,3 +1,6 @@
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+
+# buildifier: disable=bzl-visibility
 load("@rules_rust//rust/private:rust.bzl", "rust_allocator_libraries")
 
 rust_allocator_libraries(
diff --git a/ffi/rs/allocator_library/BUILD.bazel b/ffi/rs/allocator_library/BUILD.bazel
index ee02f97db4..76a776c13e 100644
--- a/ffi/rs/allocator_library/BUILD.bazel
+++ b/ffi/rs/allocator_library/BUILD.bazel
@@ -1,4 +1,6 @@
 load("@rules_rust//rust:defs.bzl", "rust_library")
+
+# buildifier: disable=bzl-visibility
 load(
     "@rules_rust//rust/private:rust.bzl",
     "rust_library_without_process_wrapper",
diff --git a/ffi/rs/global_allocator_library/BUILD.bazel b/ffi/rs/global_allocator_library/BUILD.bazel
index adbe884396..743c98d334 100644
--- a/ffi/rs/global_allocator_library/BUILD.bazel
+++ b/ffi/rs/global_allocator_library/BUILD.bazel
@@ -1,8 +1,4 @@
 load("@rules_rust//rust:defs.bzl", "rust_library")
-load(
-    "@rules_rust//rust/private:rust.bzl",
-    "rust_library_without_process_wrapper",
-)
 
 package(
     default_visibility = ["@rules_rust//ffi/rs:__subpackages__"],
diff --git a/rust/private/rust.bzl b/rust/private/rust.bzl
index 7112901672..54d6c10917 100644
--- a/rust/private/rust.bzl
+++ b/rust/private/rust.bzl
@@ -528,6 +528,13 @@ def _stamp_attribute(default_value):
 
 # Internal attributes core to Rustc actions.
 RUSTC_ATTRS = {
+    # This is really internal. Not prefixed with `_` since we need to adapt this
+    # in bootstrapping situations, e.g., when building the process wrapper
+    # or allocator libraries themselves.
+    "allocator_libraries": attr.label(
+        default = "//ffi/rs:default_allocator_libraries",
+        providers = [AllocatorLibrariesInfo],
+    ),
     "_error_format": attr.label(
         default = Label("//rust/settings:error_format"),
     ),
@@ -719,10 +726,6 @@ _common_attrs = {
         doc = "A version to inject in the cargo environment variable.",
         default = "0.0.0",
     ),
-    "allocator_libraries": attr.label(
-        default = "//ffi/rs:default_allocator_libraries",
-        providers = [AllocatorLibrariesInfo],
-    ),
     "_stamp_flag": attr.label(
         doc = "A setting used to determine whether or not the `--stamp` flag is enabled",
         default = Label("//rust/private:stamp"),
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index 247fc98e2e..b580862742 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -1609,6 +1609,14 @@ def _merge_attr_and_toolchain_alloc_info(attr_alloc_cc_info, toolchain_alloc_cc_
         fail("empty attr_alloc_cc_info")
     return cc_common.merge_cc_infos(cc_infos = [attr_alloc_cc_info, toolchain_alloc_cc_info])
 
+def _should_use_rustc_allocator_libraries(toolchain):
+    use_or_default = toolchain._experimental_use_allocator_libraries_with_mangled_symbols
+    if use_or_default not in [-1, 0, 1]:
+        fail("unexpected value of experimental_use_allocator_libraries_with_mangled_symbols (should be one of [-1, 0, 1]): " + use_or_default)
+    if use_or_default == -1:
+        return toolchain._experimental_use_allocator_libraries_with_mangled_symbols_setting
+    return bool(use_or_default)
+
 def _get_std_and_alloc_info(ctx, toolchain, crate_info):
     # Handles standard libraries and allocator shims.
     #
@@ -1624,7 +1632,7 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
     # toolchain allocator attributes.
     attr_allocator_library = None
     attr_global_allocator_library = None
-    if hasattr(ctx.attr, "allocator_libraries"):
+    if _should_use_rustc_allocator_libraries(toolchain) and hasattr(ctx.attr, "allocator_libraries"):
         attr_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].allocator_library
         attr_global_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].global_allocator_library
     if is_exec_configuration(ctx):
diff --git a/rust/settings/BUILD.bazel b/rust/settings/BUILD.bazel
index 8774b00fdb..d24237a078 100644
--- a/rust/settings/BUILD.bazel
+++ b/rust/settings/BUILD.bazel
@@ -72,7 +72,9 @@ experimental_use_coverage_metadata_files()
 
 experimental_use_global_allocator()
 
-experimental_use_allocator_libraries_with_mangled_symbols()
+experimental_use_allocator_libraries_with_mangled_symbols(
+    name = "experimental_use_allocator_libraries_with_mangled_symbols",
+)
 
 experimental_use_sh_toolchain_for_bootstrap_process_wrapper()
 
diff --git a/rust/settings/settings.bzl b/rust/settings/settings.bzl
index ef830a7384..355d526112 100644
--- a/rust/settings/settings.bzl
+++ b/rust/settings/settings.bzl
@@ -125,18 +125,20 @@ def experimental_use_global_allocator():
         build_setting_default = False,
     )
 
-def experimental_use_allocator_libraries_with_mangled_symbols():
+def experimental_use_allocator_libraries_with_mangled_symbols(name):
     """A flag used to select allocator libraries implemented in rust that are compatible with rustc's symbol mangling.
 
+    Also a corresponding config setting that can be used in selects().
+
     This currently requires nightly rustc from 2025-04-05 or later.
     """
     bool_flag(
-        name = "experimental_use_allocator_libraries_with_mangled_symbols",
+        name = name,
         build_setting_default = False,
     )
 
     native.config_setting(
-        name = "experimental_use_allocator_libraries_with_mangled_symbols_on",
+        name = "%s_on" % name,
         flag_values = {
             ":experimental_use_allocator_libraries_with_mangled_symbols": "true",
         },
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index 7171803bf5..b383131422 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -711,6 +711,8 @@ def _rust_toolchain_impl(ctx):
         _incompatible_do_not_include_data_in_compile_data = ctx.attr._incompatible_do_not_include_data_in_compile_data[IncompatibleFlagInfo].enabled,
         _no_std = no_std,
         _codegen_units = ctx.attr._codegen_units[BuildSettingInfo].value,
+        _experimental_use_allocator_libraries_with_mangled_symbols = ctx.attr.experimental_use_allocator_libraries_with_mangled_symbols,
+        _experimental_use_allocator_libraries_with_mangled_symbols_setting = ctx.attr._experimental_use_allocator_libraries_with_mangled_symbols_setting[BuildSettingInfo].value,
     )
     return [
         toolchain,
@@ -785,6 +787,19 @@ rust_toolchain = rule(
             default = Label("//rust/settings:experimental_use_cc_common_link"),
             doc = "Label to a boolean build setting that controls whether cc_common.link is used to link rust binaries.",
         ),
+        "experimental_use_allocator_libraries_with_mangled_symbols": attr.int(
+            doc = (
+                "Whether to use rust-based allocator libraries with " +
+                "mangled symbols. Possible values: [-1, 0, 1]. " +
+                "-1 means to use the value of the build setting " +
+                "//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols. " +
+                "0 means do not use. In that case, rules_rust will try to use " +
+                "the c-based allocator libraries that don't support symbol mangling. " +
+                "1 means use the rust-based allocator libraries."
+            ),
+            values = [-1, 0, 1],
+            default = -1,
+        ),
         "extra_exec_rustc_flags": attr.string_list(
             doc = "Extra flags to pass to rustc in exec configuration",
         ),
@@ -899,6 +914,14 @@ rust_toolchain = rule(
                 "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_use_global_allocator."
             ),
         ),
+        "_experimental_use_allocator_libraries_with_mangled_symbols_setting": attr.label(
+            default = Label("//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols"),
+            providers = [BuildSettingInfo],
+            doc = (
+                "Label to a boolean build setting that informs the target build whether to use rust-based " +
+                "allocator libraries that mangle symbols."
+            ),
+        ),
         "_incompatible_change_rust_test_compilation_output_directory": attr.label(
             default = Label("//rust/settings:incompatible_change_rust_test_compilation_output_directory"),
         ),

From fdfa08e4fbbbfebf2ab33a30cfe7bc3bf074f877 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 15 Apr 2025 14:19:04 +0000
Subject: [PATCH 06/19] add to its own attribute dict

---
 rust/private/rust.bzl | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/rust/private/rust.bzl b/rust/private/rust.bzl
index 54d6c10917..86bd23d867 100644
--- a/rust/private/rust.bzl
+++ b/rust/private/rust.bzl
@@ -528,13 +528,6 @@ def _stamp_attribute(default_value):
 
 # Internal attributes core to Rustc actions.
 RUSTC_ATTRS = {
-    # This is really internal. Not prefixed with `_` since we need to adapt this
-    # in bootstrapping situations, e.g., when building the process wrapper
-    # or allocator libraries themselves.
-    "allocator_libraries": attr.label(
-        default = "//ffi/rs:default_allocator_libraries",
-        providers = [AllocatorLibrariesInfo],
-    ),
     "_error_format": attr.label(
         default = Label("//rust/settings:error_format"),
     ),
@@ -571,6 +564,19 @@ RUSTC_ATTRS = {
     ),
 }
 
+# Attributes for rust-based allocator library support.
+# Can't add it directly to RUSTC_ATTRS above, as those are used as
+# aspect parameters and only support simple types ('bool', 'int' or 'string').
+_rustc_allocator_libraries_attrs = {
+    # This is really internal. Not prefixed with `_` since we need to adapt this
+    # in bootstrapping situations, e.g., when building the process wrapper
+    # or allocator libraries themselves.
+    "allocator_libraries": attr.label(
+        default = "//ffi/rs:default_allocator_libraries",
+        providers = [AllocatorLibrariesInfo],
+    ),
+}
+
 _common_attrs = {
     "aliases": attr.label_keyed_string_dict(
         doc = dedent("""\
@@ -730,7 +736,7 @@ _common_attrs = {
         doc = "A setting used to determine whether or not the `--stamp` flag is enabled",
         default = Label("//rust/private:stamp"),
     ),
-} | RUSTC_ATTRS
+} | RUSTC_ATTRS | _rustc_allocator_libraries_attrs
 
 _coverage_attrs = {
     "_collect_cc_coverage": attr.label(

From bc47c49a2bee12d9a4b0da3475c02f4edf77104a Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 15 Apr 2025 14:37:33 +0000
Subject: [PATCH 07/19] formatting

---
 rust/toolchain.bzl | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index b383131422..5240982202 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -783,10 +783,6 @@ rust_toolchain = rule(
             default = Label("@rules_rust//rust/settings:experimental_link_std_dylib"),
             doc = "Label to a boolean build setting that controls whether whether to link libstd dynamically.",
         ),
-        "experimental_use_cc_common_link": attr.label(
-            default = Label("//rust/settings:experimental_use_cc_common_link"),
-            doc = "Label to a boolean build setting that controls whether cc_common.link is used to link rust binaries.",
-        ),
         "experimental_use_allocator_libraries_with_mangled_symbols": attr.int(
             doc = (
                 "Whether to use rust-based allocator libraries with " +
@@ -800,6 +796,10 @@ rust_toolchain = rule(
             values = [-1, 0, 1],
             default = -1,
         ),
+        "experimental_use_cc_common_link": attr.label(
+            default = Label("//rust/settings:experimental_use_cc_common_link"),
+            doc = "Label to a boolean build setting that controls whether cc_common.link is used to link rust binaries.",
+        ),
         "extra_exec_rustc_flags": attr.string_list(
             doc = "Extra flags to pass to rustc in exec configuration",
         ),
@@ -907,13 +907,6 @@ rust_toolchain = rule(
         "_experimental_use_coverage_metadata_files": attr.label(
             default = Label("//rust/settings:experimental_use_coverage_metadata_files"),
         ),
-        "_experimental_use_global_allocator": attr.label(
-            default = Label("//rust/settings:experimental_use_global_allocator"),
-            doc = (
-                "Label to a boolean build setting that informs the target build whether a global allocator is being used." +
-                "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_use_global_allocator."
-            ),
-        ),
         "_experimental_use_allocator_libraries_with_mangled_symbols_setting": attr.label(
             default = Label("//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols"),
             providers = [BuildSettingInfo],
@@ -922,6 +915,13 @@ rust_toolchain = rule(
                 "allocator libraries that mangle symbols."
             ),
         ),
+        "_experimental_use_global_allocator": attr.label(
+            default = Label("//rust/settings:experimental_use_global_allocator"),
+            doc = (
+                "Label to a boolean build setting that informs the target build whether a global allocator is being used." +
+                "This flag is only relevant when used together with --@rules_rust//rust/settings:experimental_use_global_allocator."
+            ),
+        ),
         "_incompatible_change_rust_test_compilation_output_directory": attr.label(
             default = Label("//rust/settings:incompatible_change_rust_test_compilation_output_directory"),
         ),

From 34770cb6fb4d6ba849395920bb741be3ead8fa90 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 15 Apr 2025 14:39:24 +0000
Subject: [PATCH 08/19] formatting

---
 rust/toolchain.bzl | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index 5240982202..dca8e2ae94 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -904,9 +904,6 @@ rust_toolchain = rule(
         "_codegen_units": attr.label(
             default = Label("//rust/settings:codegen_units"),
         ),
-        "_experimental_use_coverage_metadata_files": attr.label(
-            default = Label("//rust/settings:experimental_use_coverage_metadata_files"),
-        ),
         "_experimental_use_allocator_libraries_with_mangled_symbols_setting": attr.label(
             default = Label("//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols"),
             providers = [BuildSettingInfo],
@@ -915,6 +912,9 @@ rust_toolchain = rule(
                 "allocator libraries that mangle symbols."
             ),
         ),
+        "_experimental_use_coverage_metadata_files": attr.label(
+            default = Label("//rust/settings:experimental_use_coverage_metadata_files"),
+        ),
         "_experimental_use_global_allocator": attr.label(
             default = Label("//rust/settings:experimental_use_global_allocator"),
             doc = (

From 911f87711faf09871f139bae37065b1deca9ba3b Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 15 Apr 2025 14:51:48 +0000
Subject: [PATCH 09/19] reformat

---
 .../rustc_std_internal_symbol_mangling/test.cc            | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
index 0cf2e6b27a..ce13d7801d 100644
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
+++ b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
@@ -3,8 +3,8 @@
 extern "C" int rdep();
 
 int main() {
-  if (rdep() != 1001) {
-    return 1;
-  }
-  return 0;
+    if (rdep() != 1001) {
+        return 1;
+    }
+    return 0;
 }

From 161c960741205e71834ffde6a4972b03edf1713a Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Mon, 28 Apr 2025 16:09:20 +0000
Subject: [PATCH 10/19] add nostd test and fix

---
 rust/private/rustc.bzl                        |  2 +-
 rust/toolchain.bzl                            |  4 +-
 .../.gitignore                                |  2 +
 .../bazel-bin                                 |  1 -
 .../bazel-out                                 |  1 -
 .../bazel-rustc_std_internal_symbol_mangling  |  1 -
 .../bazel-testlogs                            |  1 -
 .../.bazelrc                                  | 93 +++++++++++++++++++
 .../.gitignore                                |  2 +
 .../BUILD.bazel                               | 47 ++++++++++
 .../MODULE.bazel                              | 46 +++++++++
 .../WORKSPACE.bazel                           |  1 +
 .../alloc.rs                                  |  6 ++
 .../rustc_std_internal_symbol_mangling/lib.rs | 22 +++++
 .../rustc_std_internal_symbol_mangling/main.c |  9 ++
 .../main.rs                                   | 38 ++++++++
 .../no_std.rs                                 | 16 ++++
 17 files changed, 285 insertions(+), 7 deletions(-)
 create mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
 delete mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
 delete mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
 delete mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
 delete mode 120000 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/main.c
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs
 create mode 100644 test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs

diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index b580862742..6867fd8d68 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -1643,7 +1643,7 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
         if _is_no_std(ctx, toolchain, crate_info):
             if attr_global_allocator_library:
                 return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.nostd_no_allocator_ccinfo)
-            return toolchain.nostd_and_global_allocator_cc_info
+            return toolchain.nostd_and_global_allocator_ccinfo
         else:
             if attr_global_allocator_library:
                 return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.libstd_no_allocator_ccinfo)
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index dca8e2ae94..eb7c585658 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -671,9 +671,9 @@ def _rust_toolchain_impl(ctx):
         exec_triple = exec_triple,
         libstd_and_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.allocator_library, "std"),
         libstd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "std"),
-        nostd_and_global_allocator_cc_info = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "no_std_with_alloc"),
+        nostd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "no_std_with_alloc"),
         libstd_no_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "std"),
-        nostd_no_allocator_cc_info = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "no_std_with_alloc"),
+        nostd_no_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "no_std_with_alloc"),
         llvm_cov = ctx.file.llvm_cov,
         llvm_profdata = ctx.file.llvm_profdata,
         lto = lto,
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
new file mode 100644
index 0000000000..2f0f755d60
--- /dev/null
+++ b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
@@ -0,0 +1,2 @@
+/bazel-*
+/MODULE.bazel.lock
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
deleted file mode 120000
index c4a512a4ab..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-bin
+++ /dev/null
@@ -1 +0,0 @@
-/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out/k8-fastbuild/bin
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
deleted file mode 120000
index 26d54958ed..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-out
+++ /dev/null
@@ -1 +0,0 @@
-/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
deleted file mode 120000
index 276d865d02..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-rustc_std_internal_symbol_mangling
+++ /dev/null
@@ -1 +0,0 @@
-/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main
\ No newline at end of file
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
deleted file mode 120000
index ba4f7a6077..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/bazel-testlogs
+++ /dev/null
@@ -1 +0,0 @@
-/usr/local/google/home/krasimir/.cache/bazel/_bazel_krasimir/f8d75f959225228e014305ed4d8474b1/execroot/_main/bazel-out/k8-fastbuild/testlogs
\ No newline at end of file
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc
new file mode 100644
index 0000000000..887352ed0f
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc
@@ -0,0 +1,93 @@
+###############################################################################
+## Bazel Configuration Flags
+##
+## `.bazelrc` is a Bazel configuration file.
+## https://bazel.build/docs/best-practices#bazelrc-file
+###############################################################################
+
+# Build with no_std + alloc using cc_common.link infrastructure for linking
+build:no_std_alloc_using_cc_common_link --@rules_rust//rust/toolchain/channel=nightly
+build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_cc_common_link=True
+build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_global_allocator=True
+build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:no_std=alloc
+build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
+
+# Build with no_std + alloc
+build:no_std_alloc --@rules_rust//rust/toolchain/channel=nightly
+build:no_std_alloc --@rules_rust//rust/settings:no_std=alloc
+
+###############################################################################
+
+# https://bazel.build/reference/command-line-reference#flag--enable_platform_specific_config
+common --enable_platform_specific_config
+
+# Enable the only currently supported report type
+# https://bazel.build/reference/command-line-reference#flag--combined_report
+coverage --combined_report=lcov
+
+# Avoid fully cached builds reporting no coverage and failing CI
+# https://bazel.build/reference/command-line-reference#flag--experimental_fetch_all_coverage_outputs
+coverage --experimental_fetch_all_coverage_outputs
+
+# Required for some of the tests
+# https://bazel.build/reference/command-line-reference#flag--experimental_cc_shared_library
+common --experimental_cc_shared_library
+
+###############################################################################
+## Unique configuration groups
+###############################################################################
+
+# Enable use of the nightly toolchains.
+build:nightly --@rules_rust//rust/toolchain/channel=nightly
+
+# Enable rustfmt for all targets in the workspace
+build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
+build:rustfmt --output_groups=+rustfmt_checks
+
+# Enable clippy for all targets in the workspace
+build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
+build:clippy --output_groups=+clippy_checks
+
+# Enable unpretty for all targets in the workspace
+build:unpretty --aspects=@rules_rust//rust:defs.bzl%rust_unpretty_aspect
+build:unpretty --output_groups=+rust_unpretty
+
+# `unpretty` requires the nightly toolchain. See tracking issue:
+# https://github.com/rust-lang/rust/issues/43364
+build:unpretty --config=nightly
+
+###############################################################################
+## Incompatibility flags
+###############################################################################
+
+# https://github.com/bazelbuild/bazel/issues/8195
+build --incompatible_disallow_empty_glob=true
+
+# https://github.com/bazelbuild/bazel/issues/12821
+build --nolegacy_external_runfiles
+
+# Required for cargo_build_script support before Bazel 7
+build --incompatible_merge_fixed_and_default_shell_env
+
+# https://github.com/bazelbuild/bazel/issues/23043.
+build --incompatible_autoload_externally=
+
+###############################################################################
+## Bzlmod
+###############################################################################
+
+# A configuration for disabling bzlmod.
+common:no-bzlmod --noenable_bzlmod --enable_workspace
+
+# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
+common --lockfile_mode=off
+
+###############################################################################
+## Custom user flags
+##
+## This should always be the last thing in the `.bazelrc` file to ensure
+## consistent behavior when setting flags in that file as `.bazelrc` files are
+## evaluated top to bottom.
+###############################################################################
+
+try-import %workspace%/user.bazelrc
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore
new file mode 100644
index 0000000000..2f0f755d60
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore
@@ -0,0 +1,2 @@
+/bazel-*
+/MODULE.bazel.lock
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel
new file mode 100644
index 0000000000..cc90de45ec
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel
@@ -0,0 +1,47 @@
+load("@no_std_crate_index//:defs.bzl", "aliases", "all_crate_deps")
+load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
+load(
+    "@rules_rust//rust:defs.bzl",
+    "rust_binary",
+    "rust_library",
+    "rust_shared_library",
+)
+
+rust_shared_library(
+    name = "lib",
+    srcs = [
+        "lib.rs",
+        "no_std.rs",
+    ],
+    crate_features = select({
+        "@rules_rust//rust/settings:is_no_std": [],
+        "//conditions:default": ["std"],
+    }),
+    edition = "2021",
+    deps = ["custom_alloc"],
+)
+
+rust_library(
+    name = "custom_alloc",
+    srcs = ["alloc.rs"],
+    aliases = aliases(),
+    deps = all_crate_deps(normal = True),
+)
+
+cc_library(
+    name = "nostartfiles",
+    linkopts = ["-nostartfiles"],
+)
+
+rust_binary(
+    name = "main",
+    srcs = ["main.rs"],
+    aliases = aliases(),
+    deps = all_crate_deps(normal = True) + [":nostartfiles"],
+)
+
+cc_test(
+    name = "no_std_cc_test",
+    srcs = ["main.c"],
+    deps = [":lib"],
+)
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel
new file mode 100644
index 0000000000..444136f22d
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel
@@ -0,0 +1,46 @@
+module(
+    name = "rules_rust_test_no_std_rustc_std_internal_symbol_mangling",
+    version = "0.0.0",
+)
+
+bazel_dep(name = "rules_rust", version = "0.0.0")
+local_path_override(
+    module_name = "rules_rust",
+    path = "../../../..",
+)
+
+bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "bazel_skylib", version = "1.7.1")
+bazel_dep(name = "platforms", version = "0.0.11")
+
+rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.toolchain(
+    versions = [VERSION],
+)
+rust.repository_set(
+    name = "rust_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
+)
+use_repo(rust, "rust_toolchains")
+
+register_toolchains("@rust_toolchains//:all")
+
+crate = use_extension("@rules_rust//crate_universe:extensions.bzl", "crate")
+crate.spec(
+    package = "libc_alloc",
+    version = "1.0.3",
+)
+crate.from_specs(name = "no_std_crate_index")
+use_repo(crate, "no_std_crate_index")
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
new file mode 100644
index 0000000000..0a53422387
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
@@ -0,0 +1 @@
+workspace(name = "rules_rust_test_no_std_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs b/test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs
new file mode 100644
index 0000000000..3cead000a3
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs
@@ -0,0 +1,6 @@
+#![no_std]
+
+use libc_alloc::LibcAlloc;
+
+#[global_allocator]
+static ALLOCATOR: LibcAlloc = LibcAlloc;
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs b/test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs
new file mode 100644
index 0000000000..03647155f7
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs
@@ -0,0 +1,22 @@
+#![no_std]
+// These features are needed to support no_std + alloc
+#![feature(lang_items)]
+#![feature(alloc_error_handler)]
+#![feature(core_intrinsics)]
+#![allow(unused_imports)]
+use custom_alloc;
+
+#[cfg(all(not(feature = "std"), not(test)))]
+mod no_std;
+
+#[cfg(not(feature = "std"))]
+#[no_mangle]
+pub extern "C" fn return_5_in_no_std() -> i32 {
+    5
+}
+
+#[cfg(feature = "std")]
+#[no_mangle]
+pub extern "C" fn return_5_in_no_std() -> i32 {
+    6
+}
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/main.c b/test/integration/no_std/rustc_std_internal_symbol_mangling/main.c
new file mode 100644
index 0000000000..5c2b8177d1
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/main.c
@@ -0,0 +1,9 @@
+#include <assert.h>
+#include <stdint.h>
+
+extern int32_t return_5_in_no_std();
+
+int main(int argc, char** argv) {
+    assert(return_5_in_no_std() == 5);
+    return 0;
+}
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs b/test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs
new file mode 100644
index 0000000000..6d833eb49a
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs
@@ -0,0 +1,38 @@
+#![no_std]
+#![no_main]
+#![feature(lang_items)]
+
+use core::arch::asm;
+use core::arch::global_asm;
+use core::panic::PanicInfo;
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    exit(1);
+}
+
+global_asm! {
+    ".global _start",
+    "_start:",
+    "mov rdi, rsp",
+    "call start_main"
+}
+
+fn exit(status: i32) -> ! {
+    unsafe {
+        asm!(
+            "syscall",
+            in("rax") 60,
+            in("rdi") status,
+            options(noreturn)
+        );
+    }
+}
+
+#[no_mangle]
+unsafe fn start_main(_stack_top: *const u8) -> ! {
+    exit(0);
+}
+
+#[lang = "eh_personality"]
+extern "C" fn eh_personality() {}
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs b/test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs
new file mode 100644
index 0000000000..80e3568090
--- /dev/null
+++ b/test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs
@@ -0,0 +1,16 @@
+use core::intrinsics;
+use core::panic::PanicInfo;
+
+#[panic_handler]
+fn panic(_info: &PanicInfo) -> ! {
+    intrinsics::abort()
+}
+
+#[alloc_error_handler]
+#[allow(clippy::panic)]
+fn default_handler(layout: core::alloc::Layout) -> ! {
+    panic!("memory allocation of {} bytes failed", layout.size())
+}
+
+#[lang = "eh_personality"]
+extern "C" fn eh_personality() {}

From 9e2c701e021da969379a8fba12abc6acf563f001 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Mon, 28 Apr 2025 16:48:41 +0000
Subject: [PATCH 11/19] mv no_std tests to top-level

---
 .../.bazelrc                                                    | 0
 .../.gitignore                                                  | 0
 .../BUILD.bazel                                                 | 0
 .../MODULE.bazel                                                | 2 +-
 .../WORKSPACE.bazel                                             | 0
 .../alloc.rs                                                    | 0
 .../lib.rs                                                      | 0
 .../main.c                                                      | 0
 .../main.rs                                                     | 0
 .../no_std.rs                                                   | 0
 10 files changed, 1 insertion(+), 1 deletion(-)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/.bazelrc (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/.gitignore (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/BUILD.bazel (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/MODULE.bazel (97%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/WORKSPACE.bazel (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/alloc.rs (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/lib.rs (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/main.c (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/main.rs (100%)
 rename test/integration/{no_std/rustc_std_internal_symbol_mangling => no_std_rustc_std_internal_symbol_mangling}/no_std.rs (100%)

diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/.bazelrc
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/.gitignore
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/BUILD.bazel
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
similarity index 97%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
index 444136f22d..fbe6247895 100644
--- a/test/integration/no_std/rustc_std_internal_symbol_mangling/MODULE.bazel
+++ b/test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
@@ -6,7 +6,7 @@ module(
 bazel_dep(name = "rules_rust", version = "0.0.0")
 local_path_override(
     module_name = "rules_rust",
-    path = "../../../..",
+    path = "../../..",
 )
 
 bazel_dep(name = "rules_cc", version = "0.1.1")
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/alloc.rs
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/lib.rs
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/main.c b/test/integration/no_std_rustc_std_internal_symbol_mangling/main.c
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/main.c
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/main.c
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/main.rs
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs
diff --git a/test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs
similarity index 100%
rename from test/integration/no_std/rustc_std_internal_symbol_mangling/no_std.rs
rename to test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs

From 78d8446706333801dd97092f67431e18aa08d64f Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 29 Apr 2025 19:28:02 +0000
Subject: [PATCH 12/19] merge new and old no_std tests

---
 .bazelci/presubmit.yml                        | 12 +++
 rust/extensions.bzl                           |  8 ++
 rust/repositories.bzl                         |  8 +-
 rust/settings/settings.bzl                    |  9 +-
 test/integration/no_std/.bazelrc              |  4 +
 test/integration/no_std/MODULE.bazel          | 25 +++++
 .../.bazelrc                                  | 93 -------------------
 .../.gitignore                                |  2 -
 .../BUILD.bazel                               | 47 ----------
 .../MODULE.bazel                              | 46 ---------
 .../WORKSPACE.bazel                           |  1 -
 .../alloc.rs                                  |  6 --
 .../lib.rs                                    | 22 -----
 .../main.c                                    |  9 --
 .../main.rs                                   | 38 --------
 .../no_std.rs                                 | 16 ----
 16 files changed, 62 insertions(+), 284 deletions(-)
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/main.c
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs
 delete mode 100644 test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 7a931a2687..4c7bc8ed53 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -562,6 +562,18 @@ tasks:
       - "--config=no_std_alloc_using_cc_common_link"
     test_flags:
       - "--config=no_std_alloc_using_cc_common_link"
+  cc_common_link_no_std_and_mangling_ubuntu2004:
+    name: Build with no_std + alloc using cc_common.link infrastructure for linking with rust toolchain mangling alloc symbols
+    platform: ubuntu2004
+    working_directory: test/integration/no_std
+    build_targets:
+      - "//..."
+    test_targets:
+      - "//..."
+    build_flags:
+      - "--config=no_std_alloc_using_cc_common_link_and_mangled_alloc_symbols"
+    test_flags:
+      - "--config=no_std_alloc_using_cc_common_link_and_mangled_alloc_symbols"
   no_std_ubuntu2004:
     name: Build with no_std + alloc
     platform: ubuntu2004
diff --git a/rust/extensions.bzl b/rust/extensions.bzl
index b89f79898c..7be9c09a81 100644
--- a/rust/extensions.bzl
+++ b/rust/extensions.bzl
@@ -61,6 +61,7 @@ def _rust_impl(module_ctx):
                 "edition": repository_set.edition,
                 "exec_triple": repository_set.exec_triple,
                 "extra_target_triples": {repository_set.target_triple: [str(v) for v in repository_set.target_compatible_with]},
+                "target_settings": [str(v) for v in repository_set.target_settings],
                 "name": repository_set.name,
                 "rustfmt_version": repository_set.rustfmt_version,
                 "sha256s": repository_set.sha256s,
@@ -119,6 +120,7 @@ def _rust_impl(module_ctx):
                 register_toolchains = False,
                 aliases = toolchain.aliases,
                 toolchain_triples = toolchain_triples,
+                target_settings = [str(v) for v in toolchain.target_settings],
                 extra_toolchain_infos = extra_toolchain_infos,
             )
     metadata_kwargs = {}
@@ -170,6 +172,9 @@ _RUST_REPOSITORY_SET_TAG_ATTRS = {
     "target_compatible_with": attr.label_list(
         doc = "List of platform constraints this toolchain produces, for the particular target_triple this call is for.",
     ),
+    "target_settings": attr.label_list(
+        doc = "A list of `config_settings` that must be satisfied by the target configuration in order for this toolchain to be selected during toolchain resolution.",
+    ),
     "target_triple": attr.string(
         doc = "target_triple to configure.",
     ),
@@ -214,6 +219,9 @@ _RUST_TOOLCHAIN_TAG = tag_class(
         "rust_analyzer_version": attr.string(
             doc = "The version of Rustc to pair with rust-analyzer.",
         ),
+        "target_settings": attr.label_list(
+            doc = "A list of `config_settings` that must be satisfied by the target configuration in order for this toolchain to be selected during toolchain resolution.",
+        ),
         "versions": attr.string_list(
             doc = (
                 "A list of toolchain versions to download. This parameter only accepts one version " +
diff --git a/rust/repositories.bzl b/rust/repositories.bzl
index a5df38421e..7dc9d912d8 100644
--- a/rust/repositories.bzl
+++ b/rust/repositories.bzl
@@ -159,6 +159,7 @@ def rust_register_toolchains(
         compact_windows_names = _COMPACT_WINDOWS_NAMES,
         toolchain_triples = DEFAULT_TOOLCHAIN_TRIPLES,
         rustfmt_toolchain_triples = DEFAULT_TOOLCHAIN_TRIPLES,
+        target_settings = [],
         extra_toolchain_infos = None):
     """Emits a default set of toolchains for Linux, MacOS, and Freebsd
 
@@ -199,6 +200,7 @@ def rust_register_toolchains(
             toolchains. This is to avoid MAX_PATH issues.
         toolchain_triples (dict[str, str], optional): Mapping of rust target triple -> repository name to create.
         rustfmt_toolchain_triples (dict[str, str], optional): Like toolchain_triples, but for rustfmt toolchains.
+        target_settings (list of labels as strings, optional): A list of `config_settings` that must be satisfied by the target configuration in order for this toolchain to be selected during toolchain resolution.
         extra_toolchain_infos: (dict[str, dict], optional): Mapping of information about extra toolchains which were created outside of this call, which should be added to the hub repo.
     """
     if not rustfmt_version:
@@ -287,7 +289,7 @@ def rust_register_toolchains(
             exec_compatible_with_by_toolchain[toolchain.name] = triple_to_constraint_set(exec_triple)
             target_compatible_with_by_toolchain[toolchain.name] = toolchain.target_constraints
             toolchain_types[toolchain.name] = "@rules_rust//rust:toolchain"
-            toolchain_target_settings[toolchain.name] = ["@rules_rust//rust/toolchain/channel:{}".format(toolchain.channel.name)]
+            toolchain_target_settings[toolchain.name] = ["@rules_rust//rust/toolchain/channel:{}".format(toolchain.channel.name)] + target_settings
 
     for exec_triple, name in rustfmt_toolchain_triples.items():
         rustfmt_repo_name = "rustfmt_{}__{}".format(rustfmt_version.replace("/", "-"), exec_triple)
@@ -633,7 +635,7 @@ def rust_toolchain_repository(
         channel (str, optional): The channel of the Rust toolchain.
         exec_compatible_with (list, optional): A list of constraints for the execution platform for this toolchain.
         target_compatible_with (list, optional): A list of constraints for the target platform for this toolchain.
-        target_settings (list, optional): A list of config_settings that must be satisfied by the target configuration in order for this toolchain to be selected during toolchain resolution.
+        target_settings (list of labels as strings, optional): A list of config_settings that must be satisfied by the target configuration in order for this toolchain to be selected during toolchain resolution.
         allocator_library (str, optional): Target that provides allocator functions when rust_library targets are embedded in a cc_binary.
         global_allocator_library (str, optional): Target that provides allocator functions when a global allocator is used with cc_common.link.
         rustfmt_version (str, optional):  The version of rustfmt to be associated with the
@@ -1136,7 +1138,7 @@ def rust_repository_set(
         versions (list, optional): A list of toolchain versions to download. This paramter only accepts one versions
             per channel. E.g. `["1.65.0", "nightly/2022-11-02", "beta/2020-12-30"]`.
         exec_triple (str): The Rust-style target that this compiler runs on
-        target_settings (list, optional): A list of config_settings that must be satisfied by the target configuration in order for this set of toolchains to be selected during toolchain resolution.
+        target_settings (list of labels as strings, optional): A list of config_settings that must be satisfied by the target configuration in order for this set of toolchains to be selected during toolchain resolution.
         allocator_library (str, optional): Target that provides allocator functions when rust_library targets are
             embedded in a cc_binary.
         global_allocator_library (str, optional): Target that provides allocator functions a global allocator is used with cc_common.link.
diff --git a/rust/settings/settings.bzl b/rust/settings/settings.bzl
index 355d526112..01efb47e64 100644
--- a/rust/settings/settings.bzl
+++ b/rust/settings/settings.bzl
@@ -128,7 +128,7 @@ def experimental_use_global_allocator():
 def experimental_use_allocator_libraries_with_mangled_symbols(name):
     """A flag used to select allocator libraries implemented in rust that are compatible with rustc's symbol mangling.
 
-    Also a corresponding config setting that can be used in selects().
+    Also corresponding on/off config settings.
 
     This currently requires nightly rustc from 2025-04-05 or later.
     """
@@ -144,6 +144,13 @@ def experimental_use_allocator_libraries_with_mangled_symbols(name):
         },
     )
 
+    native.config_setting(
+        name = "%s_off" % name,
+        flag_values = {
+            ":experimental_use_allocator_libraries_with_mangled_symbols": "false",
+        },
+    )
+
 def experimental_use_coverage_metadata_files():
     """A flag to have coverage tooling added as `coverage_common.instrumented_files_info.metadata_files` instead of \
     reporting tools like `llvm-cov` and `llvm-profdata` as runfiles to each test.
diff --git a/test/integration/no_std/.bazelrc b/test/integration/no_std/.bazelrc
index a01c55bdfb..cab64f52a3 100644
--- a/test/integration/no_std/.bazelrc
+++ b/test/integration/no_std/.bazelrc
@@ -11,6 +11,10 @@ build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimenta
 build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_global_allocator=True
 build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:no_std=alloc
 
+build:no_std_alloc_using_cc_common_link_and_mangled_alloc_symbols --config=no_std_alloc_using_cc_common_link
+build:no_std_alloc_using_cc_common_link_and_mangled_alloc_symbols --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
+
+
 # Build with no_std + alloc
 build:no_std_alloc --@rules_rust//rust/toolchain/channel=nightly
 build:no_std_alloc --@rules_rust//rust/settings:no_std=alloc
diff --git a/test/integration/no_std/MODULE.bazel b/test/integration/no_std/MODULE.bazel
index d95c06162d..378a24efd8 100644
--- a/test/integration/no_std/MODULE.bazel
+++ b/test/integration/no_std/MODULE.bazel
@@ -10,15 +10,40 @@ local_path_override(
 )
 
 bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "platforms", version = "0.0.11")
 
 rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
 rust.toolchain(
     edition = "2021",
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_off",
+    ],
     versions = [
         "nightly/2024-10-17",
         "1.82.0",
     ],
 )
+
+# Generate a toolchain to be used for rust-based allocator symbols.
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.repository_set(
+    name = "rust_with_alloc_mangling_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_on",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
+)
 use_repo(rust, "rust_toolchains")
 
 register_toolchains("@rust_toolchains//:all")
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc
deleted file mode 100644
index 887352ed0f..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/.bazelrc
+++ /dev/null
@@ -1,93 +0,0 @@
-###############################################################################
-## Bazel Configuration Flags
-##
-## `.bazelrc` is a Bazel configuration file.
-## https://bazel.build/docs/best-practices#bazelrc-file
-###############################################################################
-
-# Build with no_std + alloc using cc_common.link infrastructure for linking
-build:no_std_alloc_using_cc_common_link --@rules_rust//rust/toolchain/channel=nightly
-build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_cc_common_link=True
-build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_global_allocator=True
-build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:no_std=alloc
-build:no_std_alloc_using_cc_common_link --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
-
-# Build with no_std + alloc
-build:no_std_alloc --@rules_rust//rust/toolchain/channel=nightly
-build:no_std_alloc --@rules_rust//rust/settings:no_std=alloc
-
-###############################################################################
-
-# https://bazel.build/reference/command-line-reference#flag--enable_platform_specific_config
-common --enable_platform_specific_config
-
-# Enable the only currently supported report type
-# https://bazel.build/reference/command-line-reference#flag--combined_report
-coverage --combined_report=lcov
-
-# Avoid fully cached builds reporting no coverage and failing CI
-# https://bazel.build/reference/command-line-reference#flag--experimental_fetch_all_coverage_outputs
-coverage --experimental_fetch_all_coverage_outputs
-
-# Required for some of the tests
-# https://bazel.build/reference/command-line-reference#flag--experimental_cc_shared_library
-common --experimental_cc_shared_library
-
-###############################################################################
-## Unique configuration groups
-###############################################################################
-
-# Enable use of the nightly toolchains.
-build:nightly --@rules_rust//rust/toolchain/channel=nightly
-
-# Enable rustfmt for all targets in the workspace
-build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
-build:rustfmt --output_groups=+rustfmt_checks
-
-# Enable clippy for all targets in the workspace
-build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
-build:clippy --output_groups=+clippy_checks
-
-# Enable unpretty for all targets in the workspace
-build:unpretty --aspects=@rules_rust//rust:defs.bzl%rust_unpretty_aspect
-build:unpretty --output_groups=+rust_unpretty
-
-# `unpretty` requires the nightly toolchain. See tracking issue:
-# https://github.com/rust-lang/rust/issues/43364
-build:unpretty --config=nightly
-
-###############################################################################
-## Incompatibility flags
-###############################################################################
-
-# https://github.com/bazelbuild/bazel/issues/8195
-build --incompatible_disallow_empty_glob=true
-
-# https://github.com/bazelbuild/bazel/issues/12821
-build --nolegacy_external_runfiles
-
-# Required for cargo_build_script support before Bazel 7
-build --incompatible_merge_fixed_and_default_shell_env
-
-# https://github.com/bazelbuild/bazel/issues/23043.
-build --incompatible_autoload_externally=
-
-###############################################################################
-## Bzlmod
-###############################################################################
-
-# A configuration for disabling bzlmod.
-common:no-bzlmod --noenable_bzlmod --enable_workspace
-
-# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
-common --lockfile_mode=off
-
-###############################################################################
-## Custom user flags
-##
-## This should always be the last thing in the `.bazelrc` file to ensure
-## consistent behavior when setting flags in that file as `.bazelrc` files are
-## evaluated top to bottom.
-###############################################################################
-
-try-import %workspace%/user.bazelrc
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore b/test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore
deleted file mode 100644
index 2f0f755d60..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-/bazel-*
-/MODULE.bazel.lock
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel
deleted file mode 100644
index cc90de45ec..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/BUILD.bazel
+++ /dev/null
@@ -1,47 +0,0 @@
-load("@no_std_crate_index//:defs.bzl", "aliases", "all_crate_deps")
-load("@rules_cc//cc:defs.bzl", "cc_library", "cc_test")
-load(
-    "@rules_rust//rust:defs.bzl",
-    "rust_binary",
-    "rust_library",
-    "rust_shared_library",
-)
-
-rust_shared_library(
-    name = "lib",
-    srcs = [
-        "lib.rs",
-        "no_std.rs",
-    ],
-    crate_features = select({
-        "@rules_rust//rust/settings:is_no_std": [],
-        "//conditions:default": ["std"],
-    }),
-    edition = "2021",
-    deps = ["custom_alloc"],
-)
-
-rust_library(
-    name = "custom_alloc",
-    srcs = ["alloc.rs"],
-    aliases = aliases(),
-    deps = all_crate_deps(normal = True),
-)
-
-cc_library(
-    name = "nostartfiles",
-    linkopts = ["-nostartfiles"],
-)
-
-rust_binary(
-    name = "main",
-    srcs = ["main.rs"],
-    aliases = aliases(),
-    deps = all_crate_deps(normal = True) + [":nostartfiles"],
-)
-
-cc_test(
-    name = "no_std_cc_test",
-    srcs = ["main.c"],
-    deps = [":lib"],
-)
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
deleted file mode 100644
index fbe6247895..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/MODULE.bazel
+++ /dev/null
@@ -1,46 +0,0 @@
-module(
-    name = "rules_rust_test_no_std_rustc_std_internal_symbol_mangling",
-    version = "0.0.0",
-)
-
-bazel_dep(name = "rules_rust", version = "0.0.0")
-local_path_override(
-    module_name = "rules_rust",
-    path = "../../..",
-)
-
-bazel_dep(name = "rules_cc", version = "0.1.1")
-bazel_dep(name = "bazel_skylib", version = "1.7.1")
-bazel_dep(name = "platforms", version = "0.0.11")
-
-rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
-
-# A recent enough version of rustc that mangles the internal allocator symbols.
-VERSION = "nightly/2025-04-08"
-
-rust.toolchain(
-    versions = [VERSION],
-)
-rust.repository_set(
-    name = "rust_linux_x86_64",
-    allocator_library = "@rules_rust//ffi/rs:empty",
-    edition = "2021",
-    exec_triple = "x86_64-unknown-linux-gnu",
-    target_compatible_with = [
-        "@platforms//cpu:x86_64",
-        "@platforms//os:linux",
-    ],
-    target_triple = "x86_64-unknown-linux-gnu",
-    versions = [VERSION],
-)
-use_repo(rust, "rust_toolchains")
-
-register_toolchains("@rust_toolchains//:all")
-
-crate = use_extension("@rules_rust//crate_universe:extensions.bzl", "crate")
-crate.spec(
-    package = "libc_alloc",
-    version = "1.0.3",
-)
-crate.from_specs(name = "no_std_crate_index")
-use_repo(crate, "no_std_crate_index")
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel
deleted file mode 100644
index 0a53422387..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/WORKSPACE.bazel
+++ /dev/null
@@ -1 +0,0 @@
-workspace(name = "rules_rust_test_no_std_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs
deleted file mode 100644
index 3cead000a3..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/alloc.rs
+++ /dev/null
@@ -1,6 +0,0 @@
-#![no_std]
-
-use libc_alloc::LibcAlloc;
-
-#[global_allocator]
-static ALLOCATOR: LibcAlloc = LibcAlloc;
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs
deleted file mode 100644
index 03647155f7..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/lib.rs
+++ /dev/null
@@ -1,22 +0,0 @@
-#![no_std]
-// These features are needed to support no_std + alloc
-#![feature(lang_items)]
-#![feature(alloc_error_handler)]
-#![feature(core_intrinsics)]
-#![allow(unused_imports)]
-use custom_alloc;
-
-#[cfg(all(not(feature = "std"), not(test)))]
-mod no_std;
-
-#[cfg(not(feature = "std"))]
-#[no_mangle]
-pub extern "C" fn return_5_in_no_std() -> i32 {
-    5
-}
-
-#[cfg(feature = "std")]
-#[no_mangle]
-pub extern "C" fn return_5_in_no_std() -> i32 {
-    6
-}
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/main.c b/test/integration/no_std_rustc_std_internal_symbol_mangling/main.c
deleted file mode 100644
index 5c2b8177d1..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/main.c
+++ /dev/null
@@ -1,9 +0,0 @@
-#include <assert.h>
-#include <stdint.h>
-
-extern int32_t return_5_in_no_std();
-
-int main(int argc, char** argv) {
-    assert(return_5_in_no_std() == 5);
-    return 0;
-}
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs
deleted file mode 100644
index 6d833eb49a..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/main.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-#![no_std]
-#![no_main]
-#![feature(lang_items)]
-
-use core::arch::asm;
-use core::arch::global_asm;
-use core::panic::PanicInfo;
-
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    exit(1);
-}
-
-global_asm! {
-    ".global _start",
-    "_start:",
-    "mov rdi, rsp",
-    "call start_main"
-}
-
-fn exit(status: i32) -> ! {
-    unsafe {
-        asm!(
-            "syscall",
-            in("rax") 60,
-            in("rdi") status,
-            options(noreturn)
-        );
-    }
-}
-
-#[no_mangle]
-unsafe fn start_main(_stack_top: *const u8) -> ! {
-    exit(0);
-}
-
-#[lang = "eh_personality"]
-extern "C" fn eh_personality() {}
diff --git a/test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs b/test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs
deleted file mode 100644
index 80e3568090..0000000000
--- a/test/integration/no_std_rustc_std_internal_symbol_mangling/no_std.rs
+++ /dev/null
@@ -1,16 +0,0 @@
-use core::intrinsics;
-use core::panic::PanicInfo;
-
-#[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
-    intrinsics::abort()
-}
-
-#[alloc_error_handler]
-#[allow(clippy::panic)]
-fn default_handler(layout: core::alloc::Layout) -> ! {
-    panic!("memory allocation of {} bytes failed", layout.size())
-}
-
-#[lang = "eh_personality"]
-extern "C" fn eh_personality() {}

From 705bdfce95f259916269279d9396fd4cf6cf78bb Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 29 Apr 2025 19:40:28 +0000
Subject: [PATCH 13/19] unify cc_common_link tests

---
 .bazelci/presubmit.yml                        | 12 +++++
 rust/extensions.bzl                           |  2 +-
 test/integration/cc_common_link/.bazelrc      |  1 +
 test/integration/cc_common_link/MODULE.bazel  | 24 ++++++++++
 .../.bazelrc                                  | 42 ----------------
 .../.gitignore                                |  2 -
 .../BUILD.bazel                               | 25 ----------
 .../MODULE.bazel                              | 48 -------------------
 .../WORKSPACE.bazel                           |  1 -
 .../rustc_std_internal_symbol_mangling/dep.rs | 13 -----
 .../test.cc                                   | 10 ----
 .../test.rs                                   |  4 --
 12 files changed, 38 insertions(+), 146 deletions(-)
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
 delete mode 100644 test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 4c7bc8ed53..8b1f02bfd6 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -534,6 +534,18 @@ tasks:
       - "//..."
     test_targets:
       - "//..."
+  cc_common_link_and_mangling_ubuntu2004:
+    name: Build via cc_common.link with rustc mangling alloc symbols
+    platform: ubuntu2004
+    working_directory: test/integration/cc_common_link
+    build_targets:
+      - "//..."
+    test_targets:
+      - "//..."
+    build_flags:
+      - "--config=mangled_alloc_symbols"
+    test_flags:
+      - "--config=mangled_alloc_symbols"
   cc_common_link_with_global_alloc_ubuntu2004:
     name: Build via cc_common.link using a global allocator
     platform: ubuntu2004
diff --git a/rust/extensions.bzl b/rust/extensions.bzl
index 7be9c09a81..99868b0dfe 100644
--- a/rust/extensions.bzl
+++ b/rust/extensions.bzl
@@ -61,10 +61,10 @@ def _rust_impl(module_ctx):
                 "edition": repository_set.edition,
                 "exec_triple": repository_set.exec_triple,
                 "extra_target_triples": {repository_set.target_triple: [str(v) for v in repository_set.target_compatible_with]},
-                "target_settings": [str(v) for v in repository_set.target_settings],
                 "name": repository_set.name,
                 "rustfmt_version": repository_set.rustfmt_version,
                 "sha256s": repository_set.sha256s,
+                "target_settings": [str(v) for v in repository_set.target_settings],
                 "urls": repository_set.urls,
                 "versions": repository_set.versions,
             }
diff --git a/test/integration/cc_common_link/.bazelrc b/test/integration/cc_common_link/.bazelrc
index 750da55999..5a87dbae73 100644
--- a/test/integration/cc_common_link/.bazelrc
+++ b/test/integration/cc_common_link/.bazelrc
@@ -3,6 +3,7 @@
 ###############################################################################
 
 build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
+build:mangled_alloc_symbols --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
 
 ###############################################################################
 
diff --git a/test/integration/cc_common_link/MODULE.bazel b/test/integration/cc_common_link/MODULE.bazel
index 4a7e3a2594..249366e6ee 100644
--- a/test/integration/cc_common_link/MODULE.bazel
+++ b/test/integration/cc_common_link/MODULE.bazel
@@ -16,6 +16,30 @@ bazel_dep(name = "platforms", version = "0.0.11")
 rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
 rust.toolchain(
     edition = "2018",
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_off",
+    ],
+)
+
+# Generate a toolchain to be used for rust-based allocator symbols.
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.repository_set(
+    name = "rust_with_alloc_mangling_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_on",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
 )
 use_repo(rust, "rust_toolchains")
 
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
deleted file mode 100644
index 44bf1ed56c..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.bazelrc
+++ /dev/null
@@ -1,42 +0,0 @@
-###############################################################################
-## Bazel Configuration Flags
-###############################################################################
-
-build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
-build --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
-
-###############################################################################
-
-# Enable rustfmt for all targets in the workspace
-build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
-build:rustfmt --output_groups=+rustfmt_checks
-
-# Enable clippy for all targets in the workspace
-build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
-build:clippy --output_groups=+clippy_checks
-
-###############################################################################
-## Incompatibility flags
-###############################################################################
-
-# https://github.com/bazelbuild/bazel/issues/8195
-build --incompatible_disallow_empty_glob=true
-
-# https://github.com/bazelbuild/bazel/issues/12821
-build --nolegacy_external_runfiles
-
-# Required for cargo_build_script support before Bazel 7
-build --incompatible_merge_fixed_and_default_shell_env
-
-# https://github.com/bazelbuild/bazel/issues/23043.
-build --incompatible_autoload_externally=
-
-###############################################################################
-## Bzlmod
-###############################################################################
-
-# A configuration for disabling bzlmod.
-common:no-bzlmod --noenable_bzlmod --enable_workspace
-
-# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
-common --lockfile_mode=off
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
deleted file mode 100644
index 2f0f755d60..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-/bazel-*
-/MODULE.bazel.lock
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
deleted file mode 100644
index 6bcad908eb..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/BUILD.bazel
+++ /dev/null
@@ -1,25 +0,0 @@
-load("@rules_cc//cc:defs.bzl", "cc_test")
-load(
-    "@rules_rust//rust:defs.bzl",
-    "rust_library",
-    "rust_test",
-)
-
-rust_library(
-    name = "rsdep",
-    srcs = ["dep.rs"],
-)
-
-rust_test(
-    name = "rstest",
-    srcs = ["test.rs"],
-    deps = [
-        ":rsdep",
-    ],
-)
-
-cc_test(
-    name = "cctest",
-    srcs = ["test.cc"],
-    deps = [":rsdep"],
-)
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
deleted file mode 100644
index f019e43a62..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/MODULE.bazel
+++ /dev/null
@@ -1,48 +0,0 @@
-# Repository setup to validate rules_rust with rustc that mangles rustc_std_internal_symbols.
-#
-# To support linking rust code into non-rust contexts, we must provide
-# implementations of the default internal rust allocator symbols, e.g.:
-# https://github.com/bazelbuild/rules_rust/blob/main/ffi/cc/allocator_library/allocator_library.cc
-#
-# Recent versions of rustc started to mangle these internal symbols,
-# rendering our c++ implementations ineffective:
-# https://github.com/rust-lang/rust/pull/127173
-module(
-    name = "rules_rust_test_cc_common_link_rustc_std_internal_symbol_mangling",
-    version = "0.0.0",
-)
-
-bazel_dep(name = "rules_rust", version = "0.0.0")
-local_path_override(
-    module_name = "rules_rust",
-    path = "../../../..",
-)
-
-bazel_dep(name = "rules_cc", version = "0.1.1")
-bazel_dep(name = "bazel_skylib", version = "1.7.1")
-bazel_dep(name = "platforms", version = "0.0.11")
-
-rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
-
-# A recent enough version of rustc that mangles the internal allocator symbols.
-VERSION = "nightly/2025-04-08"
-
-rust.toolchain(
-    versions = [VERSION],
-)
-rust.repository_set(
-    name = "rust_linux_x86_64",
-    allocator_library = "@rules_rust//ffi/rs:empty",
-    edition = "2021",
-    exec_triple = "x86_64-unknown-linux-gnu",
-    #global_allocator_library = "",
-    target_compatible_with = [
-        "@platforms//cpu:x86_64",
-        "@platforms//os:linux",
-    ],
-    target_triple = "x86_64-unknown-linux-gnu",
-    versions = [VERSION],
-)
-use_repo(rust, "rust_toolchains")
-
-register_toolchains("@rust_toolchains//:all")
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
deleted file mode 100644
index c29b7e548f..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
+++ /dev/null
@@ -1 +0,0 @@
-workspace(name = "rules_rust_test_cc_common_link_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
deleted file mode 100644
index c690c08b14..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/dep.rs
+++ /dev/null
@@ -1,13 +0,0 @@
-#[no_mangle]
-pub extern "C" fn rdep() -> i32 {
-    // Just some logic complicated enough to require heap
-    // allocations.
-    use std::convert::TryInto;
-    let mut v = vec![1, 2, 3];
-    while v.len() < 1000 {
-        let n = v.len();
-        v.push(v[n-1] + v[n-2]);
-        v.push(v[n-3]);
-    }
-    return v.len().try_into().unwrap();  // returns 1001
-}
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
deleted file mode 100644
index ce13d7801d..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.cc
+++ /dev/null
@@ -1,10 +0,0 @@
-#include <cstdio>
-
-extern "C" int rdep();
-
-int main() {
-    if (rdep() != 1001) {
-        return 1;
-    }
-    return 0;
-}
diff --git a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs b/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs
deleted file mode 100644
index 7f433b89f7..0000000000
--- a/test/integration/cc_common_link/rustc_std_internal_symbol_mangling/test.rs
+++ /dev/null
@@ -1,4 +0,0 @@
-#[test]
-fn test() {
-    assert_eq!(1001, rsdep::rdep());
-}

From 78c46cda92b438eca7a683e93b9d389984953cd8 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 29 Apr 2025 19:47:26 +0000
Subject: [PATCH 14/19] unify cc_common_link_with_global_alloc tests

---
 .bazelci/presubmit.yml                        | 12 +++++
 .../cc_common_link_with_global_alloc/.bazelrc |  1 +
 .../MODULE.bazel                              | 24 ++++++++++
 .../.bazelrc                                  | 43 -----------------
 .../.gitignore                                |  2 -
 .../BUILD.bazel                               | 17 -------
 .../MODULE.bazel                              | 37 ---------------
 .../WORKSPACE.bazel                           |  1 -
 .../main.rs                                   | 46 -------------------
 9 files changed, 37 insertions(+), 146 deletions(-)
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
 delete mode 100644 test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 8b1f02bfd6..b5b5d71752 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -562,6 +562,18 @@ tasks:
       - "//..."
     test_targets:
       - "//..."
+  cc_common_link_with_global_alloc_and_mangling_ubuntu2004:
+    name: Build via cc_common.link using a global allocator with rustc mangling alloc symbols
+    platform: ubuntu2004
+    working_directory: test/integration/cc_common_link_with_global_alloc
+    build_targets:
+      - "//..."
+    test_targets:
+      - "//..."
+    build_flags:
+      - "--config=mangled_alloc_symbols"
+    test_flags:
+      - "--config=mangled_alloc_symbols"
   cc_common_link_no_std_ubuntu2004:
     name: Build with no_std + alloc using cc_common.link infrastructure for linking
     platform: ubuntu2004
diff --git a/test/integration/cc_common_link_with_global_alloc/.bazelrc b/test/integration/cc_common_link_with_global_alloc/.bazelrc
index 9b55c26368..9cb01c8f00 100644
--- a/test/integration/cc_common_link_with_global_alloc/.bazelrc
+++ b/test/integration/cc_common_link_with_global_alloc/.bazelrc
@@ -4,6 +4,7 @@
 
 build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
 build --@rules_rust//rust/settings:experimental_use_global_allocator=True
+build:mangled_alloc_symbols --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
 
 ###############################################################################
 
diff --git a/test/integration/cc_common_link_with_global_alloc/MODULE.bazel b/test/integration/cc_common_link_with_global_alloc/MODULE.bazel
index 6d744a237d..4dfb4789e8 100644
--- a/test/integration/cc_common_link_with_global_alloc/MODULE.bazel
+++ b/test/integration/cc_common_link_with_global_alloc/MODULE.bazel
@@ -10,10 +10,34 @@ local_path_override(
 )
 
 bazel_dep(name = "rules_cc", version = "0.1.1")
+bazel_dep(name = "platforms", version = "0.0.11")
 
 rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
 rust.toolchain(
     edition = "2018",
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_off",
+    ],
+)
+# Generate a toolchain to be used for rust-based allocator symbols.
+
+# A recent enough version of rustc that mangles the internal allocator symbols.
+VERSION = "nightly/2025-04-08"
+
+rust.repository_set(
+    name = "rust_with_alloc_mangling_linux_x86_64",
+    allocator_library = "@rules_rust//ffi/rs:empty",
+    edition = "2021",
+    exec_triple = "x86_64-unknown-linux-gnu",
+    target_compatible_with = [
+        "@platforms//cpu:x86_64",
+        "@platforms//os:linux",
+    ],
+    target_settings = [
+        "@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols_on",
+    ],
+    target_triple = "x86_64-unknown-linux-gnu",
+    versions = [VERSION],
 )
 use_repo(rust, "rust_toolchains")
 
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
deleted file mode 100644
index a09e927526..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.bazelrc
+++ /dev/null
@@ -1,43 +0,0 @@
-###############################################################################
-## Bazel Configuration Flags
-###############################################################################
-
-build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
-build --@rules_rust//rust/settings:experimental_use_global_allocator=True
-build --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
-
-###############################################################################
-
-# Enable rustfmt for all targets in the workspace
-build:rustfmt --aspects=@rules_rust//rust:defs.bzl%rustfmt_aspect
-build:rustfmt --output_groups=+rustfmt_checks
-
-# Enable clippy for all targets in the workspace
-build:clippy --aspects=@rules_rust//rust:defs.bzl%rust_clippy_aspect
-build:clippy --output_groups=+clippy_checks
-
-###############################################################################
-## Incompatibility flags
-###############################################################################
-
-# https://github.com/bazelbuild/bazel/issues/8195
-build --incompatible_disallow_empty_glob=true
-
-# https://github.com/bazelbuild/bazel/issues/12821
-build --nolegacy_external_runfiles
-
-# Required for cargo_build_script support before Bazel 7
-build --incompatible_merge_fixed_and_default_shell_env
-
-# https://github.com/bazelbuild/bazel/issues/23043.
-build --incompatible_autoload_externally=
-
-###############################################################################
-## Bzlmod
-###############################################################################
-
-# A configuration for disabling bzlmod.
-common:no-bzlmod --noenable_bzlmod --enable_workspace
-
-# Disable the bzlmod lockfile, so we don't accidentally commit MODULE.bazel.lock
-common --lockfile_mode=off
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
deleted file mode 100644
index 2f0f755d60..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-/bazel-*
-/MODULE.bazel.lock
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
deleted file mode 100644
index d037a22e52..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/BUILD.bazel
+++ /dev/null
@@ -1,17 +0,0 @@
-load(
-    "@rules_rust//rust:defs.bzl",
-    "rust_binary",
-    "rust_test",
-)
-
-rust_binary(
-    name = "main",
-    srcs = ["main.rs"],
-    edition = "2021",
-)
-
-rust_test(
-    name = "global_alloc_test",
-    crate = ":main",
-    edition = "2021",
-)
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
deleted file mode 100644
index 330e590007..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/MODULE.bazel
+++ /dev/null
@@ -1,37 +0,0 @@
-module(
-    name = "rules_rust_test_cc_common_link_with_global_alloc_rustc_std_internal_symbol_mangling",
-    version = "0.0.0",
-)
-
-bazel_dep(name = "rules_rust", version = "0.0.0")
-local_path_override(
-    module_name = "rules_rust",
-    path = "../../../..",
-)
-
-bazel_dep(name = "rules_cc", version = "0.1.1")
-bazel_dep(name = "platforms", version = "0.0.11")
-
-rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
-
-# A recent enough version of rustc that mangles the internal allocator symbols.
-VERSION = "nightly/2025-04-08"
-
-rust.toolchain(
-    versions = [VERSION],
-)
-rust.repository_set(
-    name = "rust_linux_x86_64",
-    allocator_library = "@rules_rust//ffi/rs:empty",
-    edition = "2021",
-    exec_triple = "x86_64-unknown-linux-gnu",
-    target_compatible_with = [
-        "@platforms//cpu:x86_64",
-        "@platforms//os:linux",
-    ],
-    target_triple = "x86_64-unknown-linux-gnu",
-    versions = [VERSION],
-)
-use_repo(rust, "rust_toolchains")
-
-register_toolchains("@rust_toolchains//:all")
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
deleted file mode 100644
index 571df760ab..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/WORKSPACE.bazel
+++ /dev/null
@@ -1 +0,0 @@
-workspace(name = "rules_rust_test_cc_common_link_with_global_alloc_rustc_std_internal_symbol_mangling")
diff --git a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs b/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs
deleted file mode 100644
index 79dccff40f..0000000000
--- a/test/integration/cc_common_link_with_global_alloc/rustc_std_internal_symbol_mangling/main.rs
+++ /dev/null
@@ -1,46 +0,0 @@
-use std::alloc::{GlobalAlloc, Layout, System};
-use std::sync::atomic::{AtomicUsize, Ordering::SeqCst};
-
-static ALLOCATED: AtomicUsize = AtomicUsize::new(0);
-
-struct MyAllocator;
-
-unsafe impl GlobalAlloc for MyAllocator {
-    unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
-        let ret = System.alloc(layout);
-        if !ret.is_null() {
-            ALLOCATED.fetch_add(layout.size(), SeqCst);
-        }
-        ret
-    }
-
-    unsafe fn dealloc(&self, ptr: *mut u8, layout: Layout) {
-        System.dealloc(ptr, layout);
-        ALLOCATED.fetch_sub(layout.size(), SeqCst);
-    }
-}
-
-#[global_allocator]
-static GLOBAL: MyAllocator = MyAllocator;
-
-fn main() {
-    println!("allocated bytes before main: {}", ALLOCATED.load(SeqCst));
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_global_alloc_was_used() {
-        // Allocated bytes before main
-        let bytes_start = ALLOCATED.load(SeqCst);
-
-        let _x = Box::new(5); // 4 bytes
-        let _y = Box::new(true); // 1 byte
-
-        let bytes_end = ALLOCATED.load(SeqCst);
-
-        assert_eq!(bytes_end - bytes_start, 5);
-    }
-}

From a9914a4e63f98f288a5a45050f6fe7f77f1e5c45 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 29 Apr 2025 20:24:34 +0000
Subject: [PATCH 15/19] try to pass the alloc lib expliticly

---
 .bazelci/presubmit.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index b5b5d71752..109c0c8cfe 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -543,9 +543,9 @@ tasks:
     test_targets:
       - "//..."
     build_flags:
-      - "--config=mangled_alloc_symbols"
+      - "--config=mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a"
     test_flags:
-      - "--config=mangled_alloc_symbols"
+      - "--config=mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a"
   cc_common_link_with_global_alloc_ubuntu2004:
     name: Build via cc_common.link using a global allocator
     platform: ubuntu2004

From f5b87b01375c3e59e817eacdfefe3b1298737e6e Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 29 Apr 2025 20:27:14 +0000
Subject: [PATCH 16/19] ditto

---
 .bazelci/presubmit.yml                   | 4 ++--
 test/integration/cc_common_link/.bazelrc | 1 +
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml
index 109c0c8cfe..b5b5d71752 100644
--- a/.bazelci/presubmit.yml
+++ b/.bazelci/presubmit.yml
@@ -543,9 +543,9 @@ tasks:
     test_targets:
       - "//..."
     build_flags:
-      - "--config=mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a"
+      - "--config=mangled_alloc_symbols"
     test_flags:
-      - "--config=mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a"
+      - "--config=mangled_alloc_symbols"
   cc_common_link_with_global_alloc_ubuntu2004:
     name: Build via cc_common.link using a global allocator
     platform: ubuntu2004
diff --git a/test/integration/cc_common_link/.bazelrc b/test/integration/cc_common_link/.bazelrc
index 5a87dbae73..8cd41bb9d4 100644
--- a/test/integration/cc_common_link/.bazelrc
+++ b/test/integration/cc_common_link/.bazelrc
@@ -4,6 +4,7 @@
 
 build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
 build:mangled_alloc_symbols --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
+build:mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a
 
 ###############################################################################
 

From b3a613bad6720496527089cd68be5316df35685a Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 6 May 2025 13:50:25 +0000
Subject: [PATCH 17/19] put the alloc libs at the bottom of stdlibs

---
 rust/private/providers.bzl               |  3 ++
 rust/private/rust.bzl                    | 10 ++++
 rust/private/rustc.bzl                   | 15 +++---
 rust/toolchain.bzl                       | 68 ++++++++++++++----------
 test/integration/cc_common_link/.bazelrc |  1 -
 5 files changed, 62 insertions(+), 35 deletions(-)

diff --git a/rust/private/providers.bzl b/rust/private/providers.bzl
index 0ce4069ade..82868c7152 100644
--- a/rust/private/providers.bzl
+++ b/rust/private/providers.bzl
@@ -194,5 +194,8 @@ AllocatorLibrariesInfo = provider(
     fields = {
         "allocator_library": "Optional[CcInfo]: used when the default rust allocator is used",
         "global_allocator_library": "Optional[CcInfo]: used when a global rust allocator is used",
+        "libstd_and_allocator_ccinfo": "Optional[CcInfo]: used when the default rust allocator is used",
+        "libstd_and_global_allocator_ccinfo": "Optional[CcInfo]: used when a global rust allocator is used",
+        "nostd_and_global_allocator_ccinfo": "Optional[CcInfo]: used when nostd with a global rust allocator is used",
     },
 )
diff --git a/rust/private/rust.bzl b/rust/private/rust.bzl
index 86bd23d867..3d21574f04 100644
--- a/rust/private/rust.bzl
+++ b/rust/private/rust.bzl
@@ -1587,12 +1587,18 @@ rust_library_group = rule(
 )
 
 def _rust_allocator_libraries_impl(ctx):
+    toolchain = find_toolchain(ctx)
     allocator_library = ctx.attr.allocator_library[CcInfo] if ctx.attr.allocator_library else None
     global_allocator_library = ctx.attr.global_allocator_library[CcInfo] if ctx.attr.global_allocator_library else None
 
+    make_ccinfo = lambda lib, std: toolchain.make_libstd_and_allocator_ccinfo(ctx.label, ctx.actions, lib, std)
+
     providers = [AllocatorLibrariesInfo(
         allocator_library = allocator_library,
         global_allocator_library = global_allocator_library,
+        libstd_and_allocator_ccinfo = make_ccinfo(allocator_library, "std"),
+        libstd_and_global_allocator_ccinfo = make_ccinfo(global_allocator_library, "std"),
+        nostd_and_global_allocator_ccinfo = make_ccinfo(global_allocator_library, "no_std_with_alloc"),
     )]
 
     return providers
@@ -1610,6 +1616,10 @@ rust_allocator_libraries = rule(
             providers = [CcInfo],
         ),
     },
+    toolchains = [
+        str(Label("//rust:toolchain_type")),
+        "@bazel_tools//tools/cpp:toolchain_type",
+    ],
 )
 
 def _replace_illlegal_chars(name):
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index 6867fd8d68..6778ad3f81 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -1633,23 +1633,26 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
     attr_allocator_library = None
     attr_global_allocator_library = None
     if _should_use_rustc_allocator_libraries(toolchain) and hasattr(ctx.attr, "allocator_libraries"):
-        attr_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].allocator_library
-        attr_global_allocator_library = ctx.attr.allocator_libraries[AllocatorLibrariesInfo].global_allocator_library
+        libs = ctx.attr.allocator_libraries[AllocatorLibrariesInfo]
+        return libs.libstd_and_allocator_ccinfo
+        attr_allocator_library = libs.allocator_library
+        attr_global_allocator_library = libs.global_allocator_library
     if is_exec_configuration(ctx):
         if attr_allocator_library:
-            return _merge_attr_and_toolchain_alloc_info(attr_allocator_library, toolchain.libstd_no_allocator_ccinfo)
+            return libs.libstd_and_allocator_ccinfo
         return toolchain.libstd_and_allocator_ccinfo
     if toolchain._experimental_use_global_allocator:
         if _is_no_std(ctx, toolchain, crate_info):
             if attr_global_allocator_library:
-                return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.nostd_no_allocator_ccinfo)
+                return libs.nostd_and_global_allocator_ccinfo
             return toolchain.nostd_and_global_allocator_ccinfo
         else:
             if attr_global_allocator_library:
-                return _merge_attr_and_toolchain_alloc_info(attr_global_allocator_library, toolchain.libstd_no_allocator_ccinfo)
+                return libs.libstd_and_global_allocator_ccinfo
             return toolchain.libstd_and_global_allocator_ccinfo
     if attr_allocator_library:
-        return _merge_attr_and_toolchain_alloc_info(attr_allocator_library, toolchain.libstd_no_allocator_ccinfo)
+        print("ret: ", attr_allocator_library)
+        return libs.libstd_and_allocator_ccinfo
     return toolchain.libstd_and_allocator_ccinfo
 
 def _is_dylib(dep):
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index eb7c585658..b3e2964a59 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -124,7 +124,7 @@ rust_stdlib_filegroup = rule(
     },
 )
 
-def _ltl(library, ctx, cc_toolchain, feature_configuration):
+def _ltl(library, actions, cc_toolchain, feature_configuration):
     """A helper to generate `LibraryToLink` objects
 
     Args:
@@ -137,14 +137,14 @@ def _ltl(library, ctx, cc_toolchain, feature_configuration):
         LibraryToLink: A provider containing information about libraries to link.
     """
     return cc_common.create_library_to_link(
-        actions = ctx.actions,
+        actions = actions,
         feature_configuration = feature_configuration,
         cc_toolchain = cc_toolchain,
         static_library = library,
         pic_static_library = library,
     )
 
-def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "std"):
+def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label, actions, experimental_link_std_dylib, rust_std, allocator_library, std = "std"):
     """Make the CcInfo (if possible) for libstd and allocator libraries.
 
     Args:
@@ -158,7 +158,6 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
     Returns:
         A CcInfo object for the required libraries, or None if no such libraries are available.
     """
-    cc_toolchain, feature_configuration = find_cc_toolchain(ctx)
     cc_infos = []
 
     if not rust_common.stdlib_info in rust_std:
@@ -167,7 +166,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
             The `rust_lib` ({}) must be a target providing `rust_common.stdlib_info`
             (typically `rust_stdlib_filegroup` rule from @rules_rust//rust:defs.bzl).
             See https://github.com/bazelbuild/rules_rust/pull/802 for more information.
-        """).format(ctx.label, rust_std))
+        """).format(label, rust_std))
     rust_stdlib_info = rust_std[rust_common.stdlib_info]
 
     if rust_stdlib_info.self_contained_files:
@@ -176,8 +175,8 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         )
 
         linking_context, _linking_outputs = cc_common.create_linking_context_from_compilation_outputs(
-            name = ctx.label.name,
-            actions = ctx.actions,
+            name = label.name,
+            actions = actions,
             feature_configuration = feature_configuration,
             cc_toolchain = cc_toolchain,
             compilation_outputs = compilation_outputs,
@@ -188,16 +187,27 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         ))
 
     if rust_stdlib_info.std_rlibs:
+        allocator_library_inputs = []
+        if allocator_library and allocator_library.linking_context.linker_inputs:
+            allocator_library_inputs = [depset(
+                [
+                    l
+                    for inp in allocator_library.linking_context.linker_inputs.to_list()
+                    for l in inp.libraries
+                ],
+            )]
         alloc_inputs = depset(
-            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.alloc_files],
+            [_ltl(f, actions, cc_toolchain, feature_configuration) for f in rust_stdlib_info.alloc_files],
+            transitive = allocator_library_inputs,
+            order = "topological",
         )
         between_alloc_and_core_inputs = depset(
-            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.between_alloc_and_core_files],
+            [_ltl(f, actions, cc_toolchain, feature_configuration) for f in rust_stdlib_info.between_alloc_and_core_files],
             transitive = [alloc_inputs],
             order = "topological",
         )
         core_inputs = depset(
-            [_ltl(f, ctx, cc_toolchain, feature_configuration) for f in rust_stdlib_info.core_files],
+            [_ltl(f, actions, cc_toolchain, feature_configuration) for f in rust_stdlib_info.core_files],
             transitive = [between_alloc_and_core_inputs],
             order = "topological",
         )
@@ -220,7 +230,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
             ]
             core_alloc_and_panic_inputs = depset(
                 [
-                    _ltl(f, ctx, cc_toolchain, feature_configuration)
+                    _ltl(f, actions, cc_toolchain, feature_configuration)
                     for f in rust_stdlib_info.panic_files
                     if "unwind" not in f.basename
                 ],
@@ -230,7 +240,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         else:
             core_alloc_and_panic_inputs = depset(
                 [
-                    _ltl(f, ctx, cc_toolchain, feature_configuration)
+                    _ltl(f, actions, cc_toolchain, feature_configuration)
                     for f in rust_stdlib_info.panic_files
                     if "unwind" not in f.basename
                 ],
@@ -239,7 +249,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
             )
         memchr_inputs = depset(
             [
-                _ltl(f, ctx, cc_toolchain, feature_configuration)
+                _ltl(f, actions, cc_toolchain, feature_configuration)
                 for f in rust_stdlib_info.memchr_files
             ],
             transitive = [core_inputs],
@@ -247,18 +257,18 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         )
         between_core_and_std_inputs = depset(
             [
-                _ltl(f, ctx, cc_toolchain, feature_configuration)
+                _ltl(f, actions, cc_toolchain, feature_configuration)
                 for f in filtered_between_core_and_std_files
             ],
             transitive = [memchr_inputs],
             order = "topological",
         )
 
-        if _experimental_link_std_dylib(ctx):
+        if experimental_link_std_dylib:
             # std dylib has everything so that we do not need to include all std_files
             std_inputs = depset(
                 [cc_common.create_library_to_link(
-                    actions = ctx.actions,
+                    actions = actions,
                     feature_configuration = feature_configuration,
                     cc_toolchain = cc_toolchain,
                     dynamic_library = rust_stdlib_info.std_dylib,
@@ -267,7 +277,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         else:
             std_inputs = depset(
                 [
-                    _ltl(f, ctx, cc_toolchain, feature_configuration)
+                    _ltl(f, actions, cc_toolchain, feature_configuration)
                     for f in rust_stdlib_info.std_files
                 ],
                 transitive = [between_core_and_std_inputs],
@@ -276,7 +286,7 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
 
         test_inputs = depset(
             [
-                _ltl(f, ctx, cc_toolchain, feature_configuration)
+                _ltl(f, actions, cc_toolchain, feature_configuration)
                 for f in rust_stdlib_info.test_files
             ],
             transitive = [std_inputs],
@@ -296,15 +306,10 @@ def _make_libstd_and_allocator_ccinfo(ctx, rust_std, allocator_library, std = "s
         else:
             fail("Requested '{}' std mode is currently not supported.".format(std))
 
-        allocator_inputs = None
-        if allocator_library:
-            allocator_inputs = [allocator_library[CcInfo].linking_context.linker_inputs]
-
         cc_infos.append(CcInfo(
             linking_context = cc_common.create_linking_context(
                 linker_inputs = depset(
                     [link_inputs],
-                    transitive = allocator_inputs,
                     order = "topological",
                 ),
             ),
@@ -657,6 +662,12 @@ def _rust_toolchain_impl(ctx):
         fail("Either `target_triple` or `target_json` must be provided. Please update {}".format(
             ctx.label,
         ))
+    cc_toolchain, feature_configuration = find_cc_toolchain(ctx)
+    experimental_link_std_dylib = _experimental_link_std_dylib(ctx)
+    make_ccinfo = lambda label, actions, allocator_library, std: (
+        _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label, actions, experimental_link_std_dylib, rust_std, allocator_library, std)
+    )
+    make_local_ccinfo = lambda allocator_library, std: make_ccinfo(ctx.label, ctx.actions, allocator_library, std)
 
     toolchain = platform_common.ToolchainInfo(
         all_files = sysroot.all_files,
@@ -669,11 +680,12 @@ def _rust_toolchain_impl(ctx):
         dylib_ext = ctx.attr.dylib_ext,
         env = ctx.attr.env,
         exec_triple = exec_triple,
-        libstd_and_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.allocator_library, "std"),
-        libstd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "std"),
-        nostd_and_global_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, ctx.attr.global_allocator_library, "no_std_with_alloc"),
-        libstd_no_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "std"),
-        nostd_no_allocator_ccinfo = _make_libstd_and_allocator_ccinfo(ctx, rust_std, None, "no_std_with_alloc"),
+        libstd_and_allocator_ccinfo = make_local_ccinfo(ctx.attr.allocator_library[CcInfo], "std"),
+        libstd_and_global_allocator_ccinfo = make_local_ccinfo(ctx.attr.global_allocator_library[CcInfo], "std"),
+        nostd_and_global_allocator_ccinfo = make_local_ccinfo(ctx.attr.global_allocator_library[CcInfo], "no_std_with_alloc"),
+        make_libstd_and_allocator_ccinfo = make_ccinfo,
+        libstd_no_allocator_ccinfo = make_local_ccinfo(None, "std"),
+        nostd_no_allocator_ccinfo = make_local_ccinfo(None, "no_std_with_alloc"),
         llvm_cov = ctx.file.llvm_cov,
         llvm_profdata = ctx.file.llvm_profdata,
         lto = lto,
diff --git a/test/integration/cc_common_link/.bazelrc b/test/integration/cc_common_link/.bazelrc
index 8cd41bb9d4..5a87dbae73 100644
--- a/test/integration/cc_common_link/.bazelrc
+++ b/test/integration/cc_common_link/.bazelrc
@@ -4,7 +4,6 @@
 
 build --@rules_rust//rust/settings:experimental_use_cc_common_link=True
 build:mangled_alloc_symbols --@rules_rust//rust/settings:experimental_use_allocator_libraries_with_mangled_symbols=True
-build:mangled_alloc_symbols --linkopt=bazel-out/k8-fastbuild/bin/external/rules_rust+/ffi/rs/allocator_library/liballocator_library-256964584.a
 
 ###############################################################################
 

From 2dad83230da8de131bfb9d59b26a39d803df3428 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Tue, 6 May 2025 22:39:22 +0000
Subject: [PATCH 18/19] adapt allocator libs to be deps of liballoc

---
 rust/private/rustc.bzl             |  7 -------
 rust/toolchain.bzl                 | 24 +++++++++++++++---------
 test/unit/cc_info/cc_info_test.bzl |  3 +++
 3 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index 6778ad3f81..aefdb1800e 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -1604,11 +1604,6 @@ def _is_no_std(ctx, toolchain, crate_info):
         return False
     return True
 
-def _merge_attr_and_toolchain_alloc_info(attr_alloc_cc_info, toolchain_alloc_cc_info):
-    if not attr_alloc_cc_info:
-        fail("empty attr_alloc_cc_info")
-    return cc_common.merge_cc_infos(cc_infos = [attr_alloc_cc_info, toolchain_alloc_cc_info])
-
 def _should_use_rustc_allocator_libraries(toolchain):
     use_or_default = toolchain._experimental_use_allocator_libraries_with_mangled_symbols
     if use_or_default not in [-1, 0, 1]:
@@ -1634,7 +1629,6 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
     attr_global_allocator_library = None
     if _should_use_rustc_allocator_libraries(toolchain) and hasattr(ctx.attr, "allocator_libraries"):
         libs = ctx.attr.allocator_libraries[AllocatorLibrariesInfo]
-        return libs.libstd_and_allocator_ccinfo
         attr_allocator_library = libs.allocator_library
         attr_global_allocator_library = libs.global_allocator_library
     if is_exec_configuration(ctx):
@@ -1651,7 +1645,6 @@ def _get_std_and_alloc_info(ctx, toolchain, crate_info):
                 return libs.libstd_and_global_allocator_ccinfo
             return toolchain.libstd_and_global_allocator_ccinfo
     if attr_allocator_library:
-        print("ret: ", attr_allocator_library)
         return libs.libstd_and_allocator_ccinfo
     return toolchain.libstd_and_allocator_ccinfo
 
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index b3e2964a59..b7630379bf 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -188,14 +188,22 @@ def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label
 
     if rust_stdlib_info.std_rlibs:
         allocator_library_inputs = []
+
         if allocator_library and allocator_library.linking_context.linker_inputs:
-            allocator_library_inputs = [depset(
-                [
-                    l
-                    for inp in allocator_library.linking_context.linker_inputs.to_list()
-                    for l in inp.libraries
-                ],
-            )]
+            # Repackage the allocator library linker inputs as transitive
+            # inputs to the liballoc from the standard library.
+            # The pattern `linker_inputs.to_list()[0]` extracts the first
+            # `LinkerInput` from the context, which contains the allocator
+            # library artifacts. Later linker inputs contain extra linker
+            # information that was created while building the allocator library
+            # itself; this is redundant as it will be re-established by this
+            # function.
+            # The `to_list()` of the linker_inputs depset is OK, as it only
+            # happens once per allocator-library target in the build graph (and
+            # we usually only have a few).
+            link_inp = allocator_library.linking_context.linker_inputs.to_list()[0]
+            allocator_library_inputs = [depset(link_inp.libraries)]
+
         alloc_inputs = depset(
             [_ltl(f, actions, cc_toolchain, feature_configuration) for f in rust_stdlib_info.alloc_files],
             transitive = allocator_library_inputs,
@@ -684,8 +692,6 @@ def _rust_toolchain_impl(ctx):
         libstd_and_global_allocator_ccinfo = make_local_ccinfo(ctx.attr.global_allocator_library[CcInfo], "std"),
         nostd_and_global_allocator_ccinfo = make_local_ccinfo(ctx.attr.global_allocator_library[CcInfo], "no_std_with_alloc"),
         make_libstd_and_allocator_ccinfo = make_ccinfo,
-        libstd_no_allocator_ccinfo = make_local_ccinfo(None, "std"),
-        nostd_no_allocator_ccinfo = make_local_ccinfo(None, "no_std_with_alloc"),
         llvm_cov = ctx.file.llvm_cov,
         llvm_profdata = ctx.file.llvm_profdata,
         lto = lto,
diff --git a/test/unit/cc_info/cc_info_test.bzl b/test/unit/cc_info/cc_info_test.bzl
index e4d004b126..12450c2d2c 100644
--- a/test/unit/cc_info/cc_info_test.bzl
+++ b/test/unit/cc_info/cc_info_test.bzl
@@ -12,6 +12,9 @@ def _assert_cc_info_has_library_to_link(env, tut, type, ccinfo_count):
     asserts.true(env, CcInfo in tut, "rust_library should provide CcInfo")
     cc_info = tut[CcInfo]
     linker_inputs = cc_info.linking_context.linker_inputs.to_list()
+    for li in linker_inputs:
+        print("li.o: ", li.owner)
+        print("li.l: ", li.libraries)
     asserts.equals(env, ccinfo_count, len(linker_inputs))
     library_to_link = linker_inputs[0].libraries[0]
     asserts.equals(env, False, library_to_link.alwayslink)

From 47505fd17a7833e2c4769757b81d5e72e734a0d6 Mon Sep 17 00:00:00 2001
From: Krasimir Georgiev <krasimir@google.com>
Date: Thu, 8 May 2025 15:31:29 +0000
Subject: [PATCH 19/19] add an alloc impl provider

---
 rust/private/providers.bzl |  7 +++++++
 rust/private/rust.bzl      | 25 ++++++++++++++++-------
 rust/private/rustc.bzl     | 12 ++++++++---
 rust/toolchain.bzl         | 41 +++++++++++++++++++++++---------------
 4 files changed, 59 insertions(+), 26 deletions(-)

diff --git a/rust/private/providers.bzl b/rust/private/providers.bzl
index 82868c7152..5c47bf14cb 100644
--- a/rust/private/providers.bzl
+++ b/rust/private/providers.bzl
@@ -199,3 +199,10 @@ AllocatorLibrariesInfo = provider(
         "nostd_and_global_allocator_ccinfo": "Optional[CcInfo]: used when nostd with a global rust allocator is used",
     },
 )
+
+AllocatorLibrariesImplInfo = provider(
+    doc = "AllocatorLibrariesImplInfo provides the rust-generated linker input for linking rust code with a non-rust linker.",
+    fields = {
+        "static_archive": "Optional[File]: the allocator library archive (typically .a file).",
+    },
+)
diff --git a/rust/private/rust.bzl b/rust/private/rust.bzl
index 3d21574f04..dba253b1c0 100644
--- a/rust/private/rust.bzl
+++ b/rust/private/rust.bzl
@@ -17,7 +17,13 @@
 load("@bazel_skylib//lib:paths.bzl", "paths")
 load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("//rust/private:common.bzl", "COMMON_PROVIDERS", "rust_common")
-load("//rust/private:providers.bzl", "AllocatorLibrariesInfo", "BuildInfo", "LintsInfo")
+load(
+    "//rust/private:providers.bzl",
+    "AllocatorLibrariesImplInfo",
+    "AllocatorLibrariesInfo",
+    "BuildInfo",
+    "LintsInfo",
+)
 load("//rust/private:rustc.bzl", "rustc_compile_action")
 load(
     "//rust/private:utils.bzl",
@@ -1588,10 +1594,15 @@ rust_library_group = rule(
 
 def _rust_allocator_libraries_impl(ctx):
     toolchain = find_toolchain(ctx)
-    allocator_library = ctx.attr.allocator_library[CcInfo] if ctx.attr.allocator_library else None
-    global_allocator_library = ctx.attr.global_allocator_library[CcInfo] if ctx.attr.global_allocator_library else None
-
-    make_ccinfo = lambda lib, std: toolchain.make_libstd_and_allocator_ccinfo(ctx.label, ctx.actions, lib, std)
+    allocator_library = ctx.attr.allocator_library[AllocatorLibrariesImplInfo] if ctx.attr.allocator_library else None
+    global_allocator_library = ctx.attr.global_allocator_library[AllocatorLibrariesImplInfo] if ctx.attr.global_allocator_library else None
+
+    make_ccinfo = lambda info, std: toolchain.make_libstd_and_allocator_ccinfo(
+        ctx.label,
+        ctx.actions,
+        struct(allocator_libraries_impl_info = info),
+        std,
+    )
 
     providers = [AllocatorLibrariesInfo(
         allocator_library = allocator_library,
@@ -1609,11 +1620,11 @@ rust_allocator_libraries = rule(
     attrs = {
         "allocator_library": attr.label(
             doc = "An optional library to provide when a default rust allocator is used.",
-            providers = [CcInfo],
+            providers = [AllocatorLibrariesImplInfo],
         ),
         "global_allocator_library": attr.label(
             doc = "An optional library to provide when a default rust allocator is used.",
-            providers = [CcInfo],
+            providers = [AllocatorLibrariesImplInfo],
         ),
     },
     toolchains = [
diff --git a/rust/private/rustc.bzl b/rust/private/rustc.bzl
index aefdb1800e..9b6c824f4b 100644
--- a/rust/private/rustc.bzl
+++ b/rust/private/rustc.bzl
@@ -27,7 +27,7 @@ load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load(":common.bzl", "rust_common")
 load(":compat.bzl", "abs")
 load(":lto.bzl", "construct_lto_arguments")
-load(":providers.bzl", "AllocatorLibrariesInfo", "LintsInfo", "RustcOutputDiagnosticsInfo", _BuildInfo = "BuildInfo")
+load(":providers.bzl", "AllocatorLibrariesImplInfo", "AllocatorLibrariesInfo", "LintsInfo", "RustcOutputDiagnosticsInfo", _BuildInfo = "BuildInfo")
 load(":rustc_resource_set.bzl", "get_rustc_resource_set", "is_codegen_units_enabled")
 load(":stamp.bzl", "is_stamping_enabled")
 load(
@@ -1713,7 +1713,8 @@ def establish_cc_info(ctx, attr, crate_info, toolchain, cc_toolchain, feature_co
         interface_library (File): Optional interface library for cdylib crates on Windows.
 
     Returns:
-        list: A list containing the CcInfo provider
+        list: A list containing the CcInfo provider and optionally AllocatorLibrariesImplInfo provider used when this crate is used as the rust allocator library implementation.
+
     """
 
     # A test will not need to produce CcInfo as nothing can depend on test targets
@@ -1729,6 +1730,8 @@ def establish_cc_info(ctx, attr, crate_info, toolchain, cc_toolchain, feature_co
     if getattr(attr, "out_binary", False):
         return []
 
+    dot_a = None
+
     if crate_info.type == "staticlib":
         library_to_link = cc_common.create_library_to_link(
             actions = ctx.actions,
@@ -1802,7 +1805,10 @@ def establish_cc_info(ctx, attr, crate_info, toolchain, cc_toolchain, feature_co
             # TODO: if we already have an rlib in our deps, we could skip this
             cc_infos.append(libstd_and_allocator_cc_info)
 
-    return [cc_common.merge_cc_infos(cc_infos = cc_infos)]
+    providers = [cc_common.merge_cc_infos(cc_infos = cc_infos)]
+    if dot_a:
+        providers += [AllocatorLibrariesImplInfo(static_archive = dot_a)]
+    return providers
 
 def add_edition_flags(args, crate):
     """Adds the Rust edition flag to an arguments object reference
diff --git a/rust/toolchain.bzl b/rust/toolchain.bzl
index b7630379bf..c912d8101d 100644
--- a/rust/toolchain.bzl
+++ b/rust/toolchain.bzl
@@ -9,6 +9,7 @@ load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 load("//rust/platform:triple.bzl", "triple")
 load("//rust/private:common.bzl", "rust_common")
 load("//rust/private:lto.bzl", "RustLtoInfo")
+load("//rust/private:providers.bzl", "AllocatorLibrariesImplInfo")
 load("//rust/private:rust_analyzer.bzl", _rust_analyzer_toolchain = "rust_analyzer_toolchain")
 load(
     "//rust/private:rustfmt.bzl",
@@ -150,7 +151,10 @@ def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label
     Args:
         ctx (ctx): The rule's context object.
         rust_std: The Rust standard library.
-        allocator_library: The target to use for providing allocator functions.
+        allocator_library (struct): The target to use for providing allocator functions.
+          This should be a struct with either:
+          * a cc_info field of type CcInfo
+          * an allocator_libraries_impl_info field, which should be None or of type AllocatorLibrariesImplInfo.
         std: Standard library flavor. Currently only "std" and "no_std_with_alloc" are supported,
              accompanied with the default panic behavior.
 
@@ -159,6 +163,10 @@ def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label
         A CcInfo object for the required libraries, or None if no such libraries are available.
     """
     cc_infos = []
+    if not type(allocator_library) == "struct":
+        fail("todo")
+    if not any([hasattr(allocator_library, field) for field in ["cc_info", "allocator_libraries_impl_info"]]):
+        fail("todo")
 
     if not rust_common.stdlib_info in rust_std:
         fail(dedent("""\
@@ -189,20 +197,11 @@ def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label
     if rust_stdlib_info.std_rlibs:
         allocator_library_inputs = []
 
-        if allocator_library and allocator_library.linking_context.linker_inputs:
-            # Repackage the allocator library linker inputs as transitive
-            # inputs to the liballoc from the standard library.
-            # The pattern `linker_inputs.to_list()[0]` extracts the first
-            # `LinkerInput` from the context, which contains the allocator
-            # library artifacts. Later linker inputs contain extra linker
-            # information that was created while building the allocator library
-            # itself; this is redundant as it will be re-established by this
-            # function.
-            # The `to_list()` of the linker_inputs depset is OK, as it only
-            # happens once per allocator-library target in the build graph (and
-            # we usually only have a few).
-            link_inp = allocator_library.linking_context.linker_inputs.to_list()[0]
-            allocator_library_inputs = [depset(link_inp.libraries)]
+        if hasattr(allocator_library, "allocator_libraries_impl_info") and allocator_library.allocator_libraries_impl_info:
+            static_archive = allocator_library.allocator_libraries_impl_info.static_archive
+            allocator_library_inputs = [depset(
+                [_ltl(static_archive, actions, cc_toolchain, feature_configuration)],
+            )]
 
         alloc_inputs = depset(
             [_ltl(f, actions, cc_toolchain, feature_configuration) for f in rust_stdlib_info.alloc_files],
@@ -314,10 +313,15 @@ def _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label
         else:
             fail("Requested '{}' std mode is currently not supported.".format(std))
 
+        allocator_inputs = None
+        if hasattr(allocator_library, "cc_info"):
+            allocator_inputs = [allocator_library.cc_info.linking_context.linker_inputs]
+
         cc_infos.append(CcInfo(
             linking_context = cc_common.create_linking_context(
                 linker_inputs = depset(
                     [link_inputs],
+                    transitive = allocator_inputs,
                     order = "topological",
                 ),
             ),
@@ -675,7 +679,12 @@ def _rust_toolchain_impl(ctx):
     make_ccinfo = lambda label, actions, allocator_library, std: (
         _make_libstd_and_allocator_ccinfo(cc_toolchain, feature_configuration, label, actions, experimental_link_std_dylib, rust_std, allocator_library, std)
     )
-    make_local_ccinfo = lambda allocator_library, std: make_ccinfo(ctx.label, ctx.actions, allocator_library, std)
+    make_local_ccinfo = lambda allocator_library, std: make_ccinfo(
+        ctx.label,
+        ctx.actions,
+        struct(cc_info = allocator_library),
+        std,
+    )
 
     toolchain = platform_common.ToolchainInfo(
         all_files = sysroot.all_files,