rustc with musl target

[nmattia]

Project description

I would love to have a rustc version that compiles static binaries on Linux.

I've hacked one together:

commit 67cf46e3a914f9d89a6b367e261b3d33ecbf5dc5
Author: Nicolas Mattia <nicolas@nmattia.com>
Date:   Tue Oct 15 17:25:55 2019 +0200

    wip

diff --git a/pkgs/development/compilers/rust/rustc.nix b/pkgs/development/compilers/rust/rustc.nix
index 430d22f7653..069fe08c6da 100644
--- a/pkgs/development/compilers/rust/rustc.nix
+++ b/pkgs/development/compilers/rust/rustc.nix
@@ -4,6 +4,9 @@
 , pkgconfig, openssl
 , which, libffi
 , withBundledLLVM ? false
+, pkgsStatic
+, musl
+, runCommand
 }:
 
 let
@@ -51,41 +54,45 @@ in stdenv.mkDerivation rec {
   # We need rust to build rust. If we don't provide it, configure will try to download it.
   # Reference: https://github.com/rust-lang/rust/blob/master/src/bootstrap/configure.py
   configureFlags = let
-    setBuild  = "--set=target.${stdenv.buildPlatform.config}";
-    setHost   = "--set=target.${stdenv.hostPlatform.config}";
-    setTarget = "--set=target.${stdenv.targetPlatform.config}";
-    ccForBuild  = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}cc";
-    cxxForBuild = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}c++";
-    ccForHost  = "${pkgsBuildHost.targetPackages.stdenv.cc}/bin/${pkgsBuildHost.targetPackages.stdenv.cc.targetPrefix}cc";
-    cxxForHost = "${pkgsBuildHost.targetPackages.stdenv.cc}/bin/${pkgsBuildHost.targetPackages.stdenv.cc.targetPrefix}c++";
-    ccForTarget  = "${pkgsBuildTarget.targetPackages.stdenv.cc}/bin/${pkgsBuildTarget.targetPackages.stdenv.cc.targetPrefix}cc";
-    cxxForTarget = "${pkgsBuildTarget.targetPackages.stdenv.cc}/bin/${pkgsBuildTarget.targetPackages.stdenv.cc.targetPrefix}c++";
+    ccGlibc  = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}cc";
+    cxxGlibc = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}c++";
+
+    # the musl-enabled GCC and G++
+    ccMusl  = "${pkgsStatic.stdenv.cc}/bin/${pkgsStatic.stdenv.cc.targetPrefix}cc";
+    cxxMusl = "${pkgsStatic.stdenv.cc}/bin/${pkgsStatic.stdenv.cc.targetPrefix}c++";
+    muslRoot =
+      let libunwind = pkgsStatic.llvmPackages_9.libunwind.override
+            { enableShared = false; };
+      in
+      runCommand "musl-root" {}
+    ''
+      mkdir -p $out
+      cp -r ${musl}/* $out
+      chmod +w $out/lib
+      cp ${libunwind}/lib/* $out/lib
+    '';
   in [
     "--release-channel=stable"
     "--set=build.rustc=${rustPlatform.rust.rustc}/bin/rustc"
     "--set=build.cargo=${rustPlatform.rust.cargo}/bin/cargo"
     "--enable-rpath"
     "--enable-vendor"
-    "--build=${stdenv.buildPlatform.config}"
-    "--host=${stdenv.hostPlatform.config}"
-    "--target=${stdenv.targetPlatform.config}"
+    "--build=x86_64-unknown-linux-gnu"
+    "--host=x86_64-unknown-linux-gnu"
+    "--target=x86_64-unknown-linux-musl"
 
-    "${setBuild}.cc=${ccForBuild}"
-    "${setHost}.cc=${ccForHost}"
-    "${setTarget}.cc=${ccForTarget}"
+    "--set=target.x86_64-unknown-linux-gnu.cc=${ccGlibc}"
+    "--set=target.x86_64-unknown-linux-gnu.linker=${ccGlibc}"
+    "--set=target.x86_64-unknown-linux-gnu.cxx=${cxxGlibc}"
 
-    "${setBuild}.linker=${ccForBuild}"
-    "${setHost}.linker=${ccForHost}"
-    "${setTarget}.linker=${ccForTarget}"
+    "--set=target.x86_64-unknown-linux-musl.cc=${ccMusl}"
+    "--set=target.x86_64-unknown-linux-musl.linker=${ccMusl}"
+    "--set=target.x86_64-unknown-linux-musl.cxx=${cxxMusl}"
 
-    "${setBuild}.cxx=${cxxForBuild}"
-    "${setHost}.cxx=${cxxForHost}"
-    "${setTarget}.cxx=${cxxForTarget}"
+    "--set=target.x86_64-unknown-linux-musl.musl-root=${muslRoot}"
   ] ++ optional (!withBundledLLVM) [
     "--enable-llvm-link-shared"
-    "${setBuild}.llvm-config=${llvmSharedForBuild}/bin/llvm-config"
-    "${setHost}.llvm-config=${llvmSharedForHost}/bin/llvm-config"
-    "${setTarget}.llvm-config=${llvmSharedForTarget}/bin/llvm-config"
+    "--set=target.x86_64-unknown-linux-gnu.llvm-config=${llvmSharedForBuild}/bin/llvm-config"
   ] ++ optional stdenv.isLinux [
     "--enable-profiler" # build libprofiler_builtins
   ];
@@ -132,7 +139,7 @@ in stdenv.mkDerivation rec {
 
   # remove references to llvm-config in lib/rustlib/x86_64-unknown-linux-gnu/codegen-backends/librustc_codegen_llvm-llvm.so
   # and thus a transitive dependency on ncurses
-  postInstall = ''
+  postInstall = optionalString (!withBundledLLVM) ''
     find $out/lib -name "*.so" -type f -exec remove-references-to -t ${llvmShared} '{}' '+'
   '';
 

The idea is that I really, really don't want to go through the pkgsCross infrastructure as this involves using a regular rustc (pkgsBuild) but then build two static rustcs (pkgsHost + pkgsTarget) when using pkgsStatic (not even sure this is possible). Instead I'd rather just instruct the rustc build system to build an extra target (i.e. stdlib) targetting musl. The above works well (modulo the withBundledLLVM which I've always set to true so far).

Would love to hear your thoughts @dtzWill @matthewbauer .

[dingxiangfei2009]

If you are looking at cross-compilating with rustc, maybe you can check out https://github.com/tenx-tech/cargo2nix

Although, one major blocker with compiling musl binaries is that openssl on musl stops building at the moment, and it unfortunately prevents any meaningful networking application from being built.

[andrew-d]

FWIW, I just ran into this when investigating moving the firecracker derivation to be build-from-source. I can build the x86_64-unknown-linux-gnu target just fine, but the upstream project recommends using the x86_64-unknown-linux-musl target (and this is important since it provides its' own "jailer" that doesn't know about Nix).

It'd be convenient if I could just give target = "x86_64-unknown-linux-musl"; to rustPlatform.buildRustPackage, but that doesn't work today.

[nh2]

I got triggered into working on this, or at least a relevant part of it. I'm making pkgsMusl.rustc work.

I managed to build static GUI apps with GTK (nh2/static-haskell-nix#50 (comment)), and next want to build static Rust GUI apps.

Of course I'll publish/upstream what I currently have in my git tree, but for the impatient and my own record, I needed

export LD_LIBRARY_PATH="${stdenv.cc.cc.lib}/lib:$LD_LIBRARY_PATH"

got get around the libgcc_s.so error, and commit 14ee26c#diff-fb2bc02945c6ee61a9ea9fd6aeddd789 which brings upstream rustc commit rust-lang/rust@5941acd in which fixes the couldn't find libunwind.a in musl dir error, using llvmPackages_9.libraries.libunwind.

I also had to add the bootstrap compiler download to

nixpkgs/pkgs/development/compilers/rust/bootstrap.nix

Lines 7 to 8 in e0907e2

	else if stdenv.hostPlatform.system == "x86_64-linux"
	then "x86_64-unknown-linux-gnu"

.

I'm currently at

cargo:warning=/nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/include/c++/8.3.0/cmath:45:15: fatal error: math.h: No such file or directory
cargo:warning= #include_next <math.h>

[nh2]

Also super relevant are the Alpine package description and its patches: https://git.alpinelinux.org/aports/tree/community/rust?id=351e828ddb447e649acfc38775596d290f92cb05

[nh2]

Full output of my current blocker:

   Compiling rustc_save_analysis v0.0.0 (/build/rustc-1.39.0-src/src/librustc_save_analysis)
   Compiling rustc-main v0.0.0 (/build/rustc-1.39.0-src/src/rustc)
    Finished release [optimized] target(s) in 8m 01s
Copying stage0 rustc from stage0 (x86_64-unknown-linux-musl -> x86_64-unknown-linux-musl / x86_64-unknown-linux-musl)
Building stage0 codegen artifacts (x86_64-unknown-linux-musl -> x86_64-unknown-linux-musl, llvm)
   Compiling build_helper v0.1.0 (/build/rustc-1.39.0-src/src/build_helper)
   Compiling cc v1.0.35
   Compiling rustc_codegen_llvm v0.0.0 (/build/rustc-1.39.0-src/src/librustc_codegen_llvm)
   Compiling rustc_llvm v0.0.0 (/build/rustc-1.39.0-src/src/librustc_llvm)
error: failed to run custom build command for `rustc_llvm v0.0.0 (/build/rustc-1.39.0-src/src/librustc_llvm)`

Caused by:
  process didn't exit successfully: `/build/rustc-1.39.0-src/build/x86_64-unknown-linux-musl/stage0-codegen/release/build/rustc_llvm-3aa2ad75c0334416/build-script-build` (exit code: 101)
--- stdout
cargo:rerun-if-env-changed=REAL_LIBRARY_PATH_VAR
cargo:rerun-if-env-changed=REAL_LIBRARY_PATH
cargo:rerun-if-changed=/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/bin/llvm-config
cargo:rerun-if-env-changed=LLVM_CONFIG
cargo:rustc-cfg=llvm_component="aarch64"
cargo:rustc-cfg=llvm_component="amdgpu"
cargo:rustc-cfg=llvm_component="arm"
cargo:rustc-cfg=llvm_component="asmparser"
cargo:rustc-cfg=llvm_component="bitreader"
cargo:rustc-cfg=llvm_component="bitwriter"
cargo:rustc-cfg=llvm_component="hexagon"
cargo:rustc-cfg=llvm_component="instrumentation"
cargo:rustc-cfg=llvm_component="ipo"
cargo:rustc-cfg=llvm_component="linker"
cargo:rustc-cfg=llvm_component="lto"
cargo:rustc-cfg=llvm_component="mips"
cargo:rustc-cfg=llvm_component="msp430"
cargo:rustc-cfg=llvm_component="nvptx"
cargo:rustc-cfg=llvm_component="powerpc"
cargo:rustc-cfg=llvm_component="riscv"
cargo:rustc-cfg=llvm_component="sparc"
cargo:rustc-cfg=llvm_component="systemz"
cargo:rustc-cfg=llvm_component="webassembly"
cargo:rustc-cfg=llvm_component="x86"
cargo:rustc-cfg=llvm_has_msp430_asm_parser
cargo:rerun-if-changed-env=LLVM_RUSTLLVM
cargo:rerun-if-changed=../rustllvm/Linker.cpp
cargo:rerun-if-changed=../rustllvm/ArchiveWrapper.cpp
cargo:rerun-if-changed=../rustllvm/PassWrapper.cpp
cargo:rerun-if-changed=../rustllvm/rustllvm.h
cargo:rerun-if-changed=../rustllvm/.editorconfig
cargo:rerun-if-changed=../rustllvm/RustWrapper.cpp
cargo:rerun-if-changed=../rustllvm/README
TARGET = Some("x86_64-unknown-linux-musl")
OPT_LEVEL = Some("2")
HOST = Some("x86_64-unknown-linux-musl")
CXX_x86_64-unknown-linux-musl = Some("/nix/store/k1bj2ldn9572pdf3szq60k7iln45rjwz-gcc-wrapper-8.3.0/bin/c++")
CXXFLAGS_x86_64-unknown-linux-musl = Some("-ffunction-sections -fdata-sections -fPIC -m64")
CRATE_CC_NO_DEFAULTS = None
DEBUG = Some("false")
CARGO_CFG_TARGET_FEATURE = Some("fxsr,mmx,sse,sse2")
running: "/nix/store/k1bj2ldn9572pdf3szq60k7iln45rjwz-gcc-wrapper-8.3.0/bin/c++" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include" "-std=c++11" "-fno-exceptions" "-D__STDC_CONSTANT_MACROS" "-D__STDC_FORMAT_MACROS" "-D__STDC_LIMIT_MACROS" "-DLLVM_COMPONENT_AARCH64" "-DLLVM_COMPONENT_AMDGPU" "-DLLVM_COMPONENT_ARM" "-DLLVM_COMPONENT_ASMPARSER" "-DLLVM_COMPONENT_BITREADER" "-DLLVM_COMPONENT_BITWRITER" "-DLLVM_COMPONENT_HEXAGON" "-DLLVM_COMPONENT_INSTRUMENTATION" "-DLLVM_COMPONENT_IPO" "-DLLVM_COMPONENT_LINKER" "-DLLVM_COMPONENT_LTO" "-DLLVM_COMPONENT_MIPS" "-DLLVM_COMPONENT_MSP430" "-DLLVM_COMPONENT_NVPTX" "-DLLVM_COMPONENT_POWERPC" "-DLLVM_COMPONENT_RISCV" "-DLLVM_COMPONENT_SPARC" "-DLLVM_COMPONENT_SYSTEMZ" "-DLLVM_COMPONENT_WEBASSEMBLY" "-DLLVM_COMPONENT_X86" "-DNDEBUG" "-o" "/build/rustc-1.39.0-src/build/x86_64-unknown-linux-musl/stage0-codegen/x86_64-unknown-linux-musl/release/build/rustc_llvm-40f65fabdfc6e7e7/out/../rustllvm/PassWrapper.o" "-c" "../rustllvm/PassWrapper.cpp"
cargo:warning=In file included from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/DataTypes.h:28,
cargo:warning=                 from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/Types.h:17,
cargo:warning=                 from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/BitReader.h:22,
cargo:warning=                 from ../rustllvm/rustllvm.h:1,
cargo:warning=                 from ../rustllvm/PassWrapper.cpp:6:
cargo:warning=/nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/include/c++/8.3.0/cmath:45:15: fatal error: math.h: No such file or directory
cargo:warning= #include_next <math.h>
cargo:warning=               ^~~~~~~~
cargo:warning=compilation terminated.
exit code: 1

--- stderr
thread 'main' panicked at '

Internal error occurred: Command "/nix/store/k1bj2ldn9572pdf3szq60k7iln45rjwz-gcc-wrapper-8.3.0/bin/c++" "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include" "-std=c++11" "-fno-exceptions" "-D__STDC_CONSTANT_MACROS" "-D__STDC_FORMAT_MACROS" "-D__STDC_LIMIT_MACROS" "-DLLVM_COMPONENT_AARCH64" "-DLLVM_COMPONENT_AMDGPU" "-DLLVM_COMPONENT_ARM" "-DLLVM_COMPONENT_ASMPARSER" "-DLLVM_COMPONENT_BITREADER" "-DLLVM_COMPONENT_BITWRITER" "-DLLVM_COMPONENT_HEXAGON" "-DLLVM_COMPONENT_INSTRUMENTATION" "-DLLVM_COMPONENT_IPO" "-DLLVM_COMPONENT_LINKER" "-DLLVM_COMPONENT_LTO" "-DLLVM_COMPONENT_MIPS" "-DLLVM_COMPONENT_MSP430" "-DLLVM_COMPONENT_NVPTX" "-DLLVM_COMPONENT_POWERPC" "-DLLVM_COMPONENT_RISCV" "-DLLVM_COMPONENT_SPARC" "-DLLVM_COMPONENT_SYSTEMZ" "-DLLVM_COMPONENT_WEBASSEMBLY" "-DLLVM_COMPONENT_X86" "-DNDEBUG" "-o" "/build/rustc-1.39.0-src/build/x86_64-unknown-linux-musl/stage0-codegen/x86_64-unknown-linux-musl/release/build/rustc_llvm-40f65fabdfc6e7e7/out/../rustllvm/PassWrapper.o" "-c" "../rustllvm/PassWrapper.cpp" with args "c++" did not execute successfully (status code exit code: 1).

', /build/rustc-1.39.0-src/vendor/cc/src/lib.rs:2398:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

command did not execute successfully: "/nix/store/21gn0gg7h187wfbw8jb6ywi5id7vi1yw-cargo-bootstrap-1.38.0/bin/cargo" "build" "-Zconfig-profile" "--target" "x86_64-unknown-linux-musl" "-Zbinary-dep-depinfo" "-j" "12" "--release" "--frozen" "--manifest-path" "/build/rustc-1.39.0-src/src/librustc_codegen_llvm/Cargo.toml" "--features" "" "--message-format" "json-render-diagnostics"
expected success, got: exit code: 101
failed to run: /build/rustc-1.39.0-src/build/bootstrap/debug/bootstrap build --jobs 12

[nmattia]

I've given up on rustc as packaged in nixpkgs. I'm using this instead, copied and tweaked from an older version of nixpkgs:

Only in rust/: 1_38_0.nix
Only in rust/: 1_39_0.nix
diff /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/bootstrap.nix rust/bootstrap.nix
1c1
< { stdenv, fetchurl, callPackage, version, hashes }:
---
> { stdenv, fetchurl, callPackage }:
3a4,17
>   # Note: the version MUST be one version prior to the version we're
>   # building
>   version = "1.38.0";
> 
>   # fetch hashes by running `print-hashes.sh 1.38.0`
>   hashes = {
>    i686-unknown-linux-gnu = "41aed8a350e24a0cac1444ed99b3dd24a90bc581dd88cb420c6e547d6b5f57af";
>    x86_64-unknown-linux-gnu = "adda26b3f0609dbfbdc2019da4a20101879b9db2134fae322a4e863a069ec221";
>    armv7-unknown-linux-gnueabihf = "8b1bf1680a61a643d6b5c7a3b1a1ce88448652756395e20ba5846739cbd085c4";
>    aarch64-unknown-linux-gnu = "06afd6d525326cea95c3aa658aaa8542eab26f44235565bb16913ac9d12b7bda";
>    i686-apple-darwin = "cdbf2807774bed350a3af6f41d7f7dd7ceff28777cde310c3ba90033188eb2f8";
>    x86_64-apple-darwin = "bd301b78ddcd5d4553962b115e1dca5436dd3755ed323f86f4485769286a8a5a";
>   };
> 
diff /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/default.nix rust/default.nix
1,6d0
< { rustcVersion
< , rustcSha256
< , bootstrapVersion
< , bootstrapHashes
< , selectRustPackage
< }:
12c6
< , pkgsBuildTarget, pkgsBuildBuild
---
> , path
19c13,14
<     buildRustPackage = callPackage ../../../build-support/rust {
---
>     # XXX: we should probably replace this with naersk
>     buildRustPackage = callPackage (path + /pkgs/build-support/rust) {
22c17
<       fetchcargo = buildPackages.callPackage ../../../build-support/rust/fetchcargo.nix {
---
>       fetchcargo = buildPackages.callPackage (path + /pkgs/build-support/rust/fetchcargo.nix) {
45,48c40
<     prebuilt = callPackage ./bootstrap.nix {
<       version = bootstrapVersion;
<       hashes = bootstrapHashes;
<     };
---
>     prebuilt = callPackage ./bootstrap.nix {};
55c47
<           (selectRustPackage buildPackages).packages.prebuilt);
---
>           buildPackages.rust.packages.prebuilt);
59c51
<       buildRustPackages = (selectRustPackage buildPackages).packages.stable;
---
>       buildRustPackages = buildPackages.rust.packages.stable;
63,65d54
<         version = rustcVersion;
<         sha256 = rustcSha256;
< 
70,72c59,61
<         pkgsBuildBuild = pkgsBuildBuild // { targetPackages.stdenv = llvmPackages_5.stdenv; };
<         pkgsBuildHost = pkgsBuildBuild // { targetPackages.stdenv = llvmPackages_5.stdenv; };
<         pkgsBuildTarget = pkgsBuildTarget // { targetPackages.stdenv = llvmPackages_5.stdenv; };
---
>         #pkgsBuildBuild = pkgsBuildBuild // { targetPackages.stdenv = llvmPackages_5.stdenv; };
>         #pkgsBuildHost = pkgsBuildBuild // { targetPackages.stdenv = llvmPackages_5.stdenv; };
>         #pkgsBuildTarget = pkgsBuildTarget // { targetPackages.stdenv = llvmPackages_5.stdenv; };
Common subdirectories: /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/rls and rust/rls
diff /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/rust-src.nix rust/rust-src.nix
9c9
<     rm -rf $out/{ci,doc,etc,grammar,llvm-project,llvm-emscripten,rtstartup,rustllvm,test,tools,vendor,stdarch}
---
>     rm -rf $out/{ci,doc,driver,etc,grammar,llvm,rt,rtstartup,rustllvm,test,tools,vendor}
diff /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/rustc.nix rust/rustc.nix
1c1,2
< { stdenv, removeReferencesTo, pkgsBuildBuild, pkgsBuildHost, pkgsBuildTarget
---
> { stdenv, removeReferencesTo
> , lib
3c4
< , llvm_9, darwin, git, cmake, rustPlatform
---
> , llvm_8, llvmPackages_8, darwin, git, cmake, rustPlatform
7,8c8,12
< , version
< , sha256
---
> , pkgsStatic
> , pkgs
> , runCommand
> , musl
> , makeWrapper
10a15,23
> # We make some assumptions about the platform below, this is just a sanity
> # check
> assert
>   if stdenv.isLinux then
>     stdenv.buildPlatform.config == "x86_64-unknown-linux-gnu"
>   else
>     stdenv.buildPlatform.config == "x86_64-apple-darwin"
>   ;
> 
11a25,33
>   targets =
>     [
>       "${stdenv.buildPlatform.config}"
>       "wasm32-unknown-unknown"
>     ]
>     # on Linux we also build the musl target for fully static executables
>     ++ lib.optionals stdenv.isLinux [ "x86_64-unknown-linux-musl" ]
>     ;
>   host = stdenv.buildPlatform.config;
15,18d36
<   llvmSharedForBuild = pkgsBuildBuild.llvm_9.override { enableSharedLibraries = true; };
<   llvmSharedForHost = pkgsBuildHost.llvm_9.override { enableSharedLibraries = true; };
<   llvmSharedForTarget = pkgsBuildTarget.llvm_9.override { enableSharedLibraries = true; };
< 
20c38
<   llvmShared = llvm_9.override { enableSharedLibraries = true; };
---
>   llvmShared = llvm_8.override { enableSharedLibraries = true; };
23c41
<   inherit version;
---
>   version = "1.39.0";
27c45
<     inherit sha256;
---
>     sha256 = "0mwkc1bnil2cfyf6nglpvbn2y0zfbv44zfhsd5qg4c9rm6vgd8dl";
48c66
<     ++ optional stdenv.isDarwin "-rpath ${llvmSharedForHost}/lib";
---
>     ++ optional stdenv.isDarwin "-rpath ${llvmShared}/lib";
56,64c74,94
<     setBuild  = "--set=target.${stdenv.buildPlatform.config}";
<     setHost   = "--set=target.${stdenv.hostPlatform.config}";
<     setTarget = "--set=target.${stdenv.targetPlatform.config}";
<     ccForBuild  = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}cc";
<     cxxForBuild = "${pkgsBuildBuild.targetPackages.stdenv.cc}/bin/${pkgsBuildBuild.targetPackages.stdenv.cc.targetPrefix}c++";
<     ccForHost  = "${pkgsBuildHost.targetPackages.stdenv.cc}/bin/${pkgsBuildHost.targetPackages.stdenv.cc.targetPrefix}cc";
<     cxxForHost = "${pkgsBuildHost.targetPackages.stdenv.cc}/bin/${pkgsBuildHost.targetPackages.stdenv.cc.targetPrefix}c++";
<     ccForTarget  = "${pkgsBuildTarget.targetPackages.stdenv.cc}/bin/${pkgsBuildTarget.targetPackages.stdenv.cc.targetPrefix}cc";
<     cxxForTarget = "${pkgsBuildTarget.targetPackages.stdenv.cc}/bin/${pkgsBuildTarget.targetPackages.stdenv.cc.targetPrefix}c++";
---
>     ccForBuild  = "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}cc";
>     cxxForBuild = "${stdenv.cc}/bin/${stdenv.cc.targetPrefix}c++";
> 
>     # musl-enabled cc, used in linux builds
>     ccMusl  = "${pkgsStatic.stdenv.cc}/bin/${pkgsStatic.stdenv.cc.targetPrefix}cc";
>     cxxMusl = "${pkgsStatic.stdenv.cc}/bin/${pkgsStatic.stdenv.cc.targetPrefix}c++";
>     muslRoot =
>       # the musl-root requires a libunwind.a, so we provide one from llvm
>       # XXX: create ticket about libunwind.a from LLVM breaking because rustc
>       # doesn't link-in libstdc++
>       let libunwind = pkgsStatic.callPackage ../packages/libunwind.nix
>             { enableShared = false; };
>       in
>       runCommand "musl-root" {}
>     ''
>       mkdir -p $out
>       cp -r ${musl}/* $out
>       chmod +w $out/lib
>       cp ${libunwind}/lib/libunwind.a $out/lib/libunwind.a
>     '';
> 
73,86c103
<     "--target=${stdenv.targetPlatform.config}"
< 
<     "${setBuild}.cc=${ccForBuild}"
<     "${setHost}.cc=${ccForHost}"
<     "${setTarget}.cc=${ccForTarget}"
< 
<     "${setBuild}.linker=${ccForBuild}"
<     "${setHost}.linker=${ccForHost}"
<     "${setTarget}.linker=${ccForTarget}"
< 
<     "${setBuild}.cxx=${cxxForBuild}"
<     "${setHost}.cxx=${cxxForHost}"
<     "${setTarget}.cxx=${cxxForTarget}"
<   ] ++ optional (!withBundledLLVM) [
---
>     "--target=${lib.concatStringsSep "," targets}"
88,91c105,117
<     "${setBuild}.llvm-config=${llvmSharedForBuild}/bin/llvm-config"
<     "${setHost}.llvm-config=${llvmSharedForHost}/bin/llvm-config"
<     "${setTarget}.llvm-config=${llvmSharedForTarget}/bin/llvm-config"
<   ] ++ optional stdenv.isLinux [
---
>     "--set=target.${stdenv.buildPlatform.config}.llvm-config=${llvmShared}/bin/llvm-config"
>     ] ++ lib.optionals stdenv.isLinux
>     [
>     "--set=target.x86_64-unknown-linux-gnu.cc=${ccForBuild}"
>     "--set=target.x86_64-unknown-linux-gnu.linker=${ccForBuild}"
>     "--set=target.x86_64-unknown-linux-gnu.cxx=${cxxForBuild}"
> 
>     "--set=target.x86_64-unknown-linux-musl.cc=${ccMusl}"
>     "--set=target.x86_64-unknown-linux-musl.linker=${ccMusl}"
>     "--set=target.x86_64-unknown-linux-musl.cxx=${cxxMusl}"
>     "--set=target.x86_64-unknown-linux-musl.musl-root=${muslRoot}"
> 
> 
93c119,124
<   ];
---
>     ] ++ lib.optionals stdenv.isDarwin
>     [
>     "--set=target.x86_64-apple-darwin.cc=${ccForBuild}"
>     "--set=target.x86_64-apple-darwin.linker=${ccForBuild}"
>     "--set=target.x86_64-apple-darwin.cxx=${cxxForBuild}"
>     ];
125c156
<     which libffi removeReferencesTo pkgconfig
---
>     which libffi removeReferencesTo pkgconfig makeWrapper
136a168
>   # XXX: change path wrapping
138a171,176
> 
>     # rustdoc needs a cc
>     # we wrap it with a new PATH until 1.39:
>     # https://github.com/rust-lang/cargo/issues/7529
>     wrapProgram $out/bin/rustdoc \
>       --prefix PATH ":" "${stdenv.cc}/bin"
diff /Users/nicolas/nixpkgs/pkgs/development/compilers/rust/setup-hook.sh rust/setup-hook.sh
2c2
< if [[ -z ${IN_NIX_SHELL-} && -z ${CARGO_HOME-} ]]; then
---
> if [[ -z $IN_NIX_SHELL && -z $CARGO_HOME ]]; then

with libunwind:

# We need libunwind-9.0.0 because earlier versions link c++ symbols we don't
# have to have to link to
{ fetchurl, stdenv, cmake, enableShared ? true }:
let
  version = "9.0.0";
  fetch = sha256: fetchurl {
    url = "https://releases.llvm.org/${version}/libunwind-${version}.src.tar.xz";
    inherit sha256;
  };
in
stdenv.mkDerivation rec {
  pname = "libunwind";
  inherit version;

  src = fetch "1chd1nz4bscrs6qa7p8sqgk5df86ll0frv0f451vhks2w44qsslp";

  nativeBuildInputs = [ cmake ];

  enableParallelBuilding = true;

  cmakeFlags = stdenv.lib.optional (!enableShared) "-DLIBUNWIND_ENABLE_SHARED=OFF";
}

Hope that helps, let me know if you have any questions.

[nh2]

Still struggling with the includ error.

$ /nix/store/k1bj2ldn9572pdf3szq60k7iln45rjwz-gcc-wrapper-8.3.0/bin/c++ "-O2" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-ffunction-sections" "-fdata-sections" "-fPIC" "-m64" "-I/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include" "-std=c++11" "-fno-exceptions" "-D__STDC_CONSTANT_MACROS" "-D__STDC_FORMAT_MACROS" "-D__STDC_LIMIT_MACROS" "-DLLVM_COMPONENT_AARCH64" "-DLLVM_COMPONENT_AMDGPU" "-DLLVM_COMPONENT_ARM" "-DLLVM_COMPONENT_ASMPARSER" "-DLLVM_COMPONENT_BITREADER" "-DLLVM_COMPONENT_BITWRITER" "-DLLVM_COMPONENT_HEXAGON" "-DLLVM_COMPONENT_INSTRUMENTATION" "-DLLVM_COMPONENT_IPO" "-DLLVM_COMPONENT_LINKER" "-DLLVM_COMPONENT_LTO" "-DLLVM_COMPONENT_MIPS" "-DLLVM_COMPONENT_MSP430" "-DLLVM_COMPONENT_NVPTX" "-DLLVM_COMPONENT_POWERPC" "-DLLVM_COMPONENT_RISCV" "-DLLVM_COMPONENT_SPARC" "-DLLVM_COMPONENT_SYSTEMZ" "-DLLVM_COMPONENT_WEBASSEMBLY" "-DLLVM_COMPONENT_X86" "-DNDEBUG" "-o" "/build/rustc-1.39.0-src/build/x86_64-unknown-linux-musl/stage0-codegen/x86_64-unknown-linux-musl/release/build/rustc_llvm-40f65fabdfc6e7e7/out/../rustllvm/PassWrapper.o" "-c" "../rustllvm/PassWrapper.cpp" -idirafter asdf -v
...
GNU C++11 (GCC) version 8.3.0 (x86_64-unknown-linux-musl)
	compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.17.1-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring duplicate directory "/nix/store/9zg130vcrkz1rfrkjrxrh94wqgzgadr1-file-5.37/include"
ignoring duplicate directory "/nix/store/26n4hxnaw8rkfvw20f3v23cg2wyp32id-python-2.7.16/include"
ignoring duplicate directory "/nix/store/n6rwwc63pzxc03bphc8ac6fdkyxfwpgf-libffi-3.2.1-dev/include"
ignoring duplicate directory "/nix/store/djr3xbw4k3w8nm6qxv884vahfhw2szm5-musl-1.1.22-dev/include"
ignoring duplicate directory "/nix/store/khkpaayqdqzv5ja88jjwsi5zg07xk4jk-openssl-1.1.1d-dev/include"
ignoring duplicate directory "/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include"
ignoring duplicate directory "/nix/store/5cjsn99jwpyfc03y1va0xdhwd12vs7di-ncurses-6.1-20190112-dev/include"
ignoring duplicate directory "/nix/store/kav11lvmpykhr8ikn4r1wzdhzl4330fq-zlib-1.2.11-dev/include"
ignoring nonexistent directory "/nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/../../../../x86_64-unknown-linux-musl/include"
ignoring duplicate directory "/nix/store/djr3xbw4k3w8nm6qxv884vahfhw2szm5-musl-1.1.22-dev/include"
ignoring nonexistent directory "asdf"
ignoring duplicate directory "/nix/store/djr3xbw4k3w8nm6qxv884vahfhw2szm5-musl-1.1.22-dev/include"
ignoring duplicate directory "/nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include"
  as it is a non-system directory that duplicates a system directory
#include "..." search starts here:
#include <...> search starts here:
 /nix/store/9zg130vcrkz1rfrkjrxrh94wqgzgadr1-file-5.37/include
 /nix/store/26n4hxnaw8rkfvw20f3v23cg2wyp32id-python-2.7.16/include
 /nix/store/n6rwwc63pzxc03bphc8ac6fdkyxfwpgf-libffi-3.2.1-dev/include
 /nix/store/djr3xbw4k3w8nm6qxv884vahfhw2szm5-musl-1.1.22-dev/include
 /nix/store/khkpaayqdqzv5ja88jjwsi5zg07xk4jk-openssl-1.1.1d-dev/include
 /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include
 /nix/store/5cjsn99jwpyfc03y1va0xdhwd12vs7di-ncurses-6.1-20190112-dev/include
 /nix/store/kav11lvmpykhr8ikn4r1wzdhzl4330fq-zlib-1.2.11-dev/include
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/../../../../include/c++/8.3.0
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/../../../../include/c++/8.3.0/x86_64-unknown-linux-musl
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/../../../../include/c++/8.3.0/backward
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/include
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/include
 /nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/lib/gcc/x86_64-unknown-linux-musl/8.3.0/include-fixed
End of search list.
GNU C++11 (GCC) version 8.3.0 (x86_64-unknown-linux-musl)
	compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.2, MPC version 1.1.0, isl version isl-0.17.1-GMP

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 648f9d22571b7b9c46e5f05e2d3aee6f
In file included from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/DataTypes.h:28,
                 from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/Types.h:17,
                 from /nix/store/77cdrqqd7icjca7y91ivlrj9k9igaf1d-llvm-9.0.0/include/llvm-c/BitReader.h:22,
                 from ../rustllvm/rustllvm.h:1,
                 from ../rustllvm/PassWrapper.cpp:6:
/nix/store/68kld13k9h11lj13zk3il4x6fxncwxkh-gcc-8.3.0/include/c++/8.3.0/cmath:45:15: fatal error: math.h: No such file or directory
 #include_next <math.h>
               ^~~~~~~~
compilation terminated.

[nh2]

I can't figure out how to add stuff to the end of the search path.

Even my -idirafter asdf is added before the relevant includes.

[nh2]

I got it to build.

-idirafter on the musl include dir didn't work because the musl path was already a normal -isystem, and the deduplication logic ignored -idirafter in that case.

My mistake was to add musl/musl.dev to buildInputs of rustc in the first place.

I've pushed my WIP to nh2@70e7b40 (part of my hacky gtk3-static branch for now).

[nh2]

Next obstacle (when building cargo after rustc has built):

error: cannot produce proc-macro for `failure_derive v0.1.5` as the target `x86_64-unknown-linux-musl` does not support these crate types

Which is probably rust-lang/rust#40174.