diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index 2197dd68eaf69..0b94602231376 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -5,7 +5,6 @@
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
 #![cfg_attr(feature = "nightly", feature(rustdoc_internals))]
 #![cfg_attr(feature = "nightly", feature(step_trait))]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 /*! ABI handling for rustc
diff --git a/compiler/rustc_arena/src/lib.rs b/compiler/rustc_arena/src/lib.rs
index b21ccba93bb44..d72f6a9c924ea 100644
--- a/compiler/rustc_arena/src/lib.rs
+++ b/compiler/rustc_arena/src/lib.rs
@@ -23,7 +23,6 @@
 #![feature(maybe_uninit_slice)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::alloc::Layout;
diff --git a/compiler/rustc_ast/src/lib.rs b/compiler/rustc_ast/src/lib.rs
index 6372c66050e7c..294c6c9ba7a50 100644
--- a/compiler/rustc_ast/src/lib.rs
+++ b/compiler/rustc_ast/src/lib.rs
@@ -19,7 +19,6 @@
 #![feature(never_type)]
 #![feature(rustdoc_internals)]
 #![feature(stmt_expr_attributes)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod util {
diff --git a/compiler/rustc_ast_ir/src/lib.rs b/compiler/rustc_ast_ir/src/lib.rs
index 9884e191ea7bd..6d05cd18cec12 100644
--- a/compiler/rustc_ast_ir/src/lib.rs
+++ b/compiler/rustc_ast_ir/src/lib.rs
@@ -9,7 +9,6 @@
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", feature(never_type))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 #[cfg(feature = "nightly")]
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 13edcc10c9e2a..5f5bb3a601577 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -38,7 +38,6 @@
 #![feature(if_let_guard)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::sync::Arc;
diff --git a/compiler/rustc_ast_passes/src/lib.rs b/compiler/rustc_ast_passes/src/lib.rs
index b4ed70d83e570..093199cf34212 100644
--- a/compiler/rustc_ast_passes/src/lib.rs
+++ b/compiler/rustc_ast_passes/src/lib.rs
@@ -10,7 +10,6 @@
 #![feature(iter_is_partitioned)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod ast_validation;
diff --git a/compiler/rustc_ast_pretty/src/lib.rs b/compiler/rustc_ast_pretty/src/lib.rs
index 602ab69ee5b5d..84d9ce278a21a 100644
--- a/compiler/rustc_ast_pretty/src/lib.rs
+++ b/compiler/rustc_ast_pretty/src/lib.rs
@@ -3,7 +3,6 @@
 #![doc(rust_logo)]
 #![feature(box_patterns)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod helpers;
diff --git a/compiler/rustc_attr_data_structures/src/lib.rs b/compiler/rustc_attr_data_structures/src/lib.rs
index e4bb459e6df5a..d90be4bd5fe8f 100644
--- a/compiler/rustc_attr_data_structures/src/lib.rs
+++ b/compiler/rustc_attr_data_structures/src/lib.rs
@@ -3,7 +3,6 @@
 #![doc(rust_logo)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod attributes;
diff --git a/compiler/rustc_attr_parsing/src/lib.rs b/compiler/rustc_attr_parsing/src/lib.rs
index 9841166b37dbd..aab6fdc8cf30d 100644
--- a/compiler/rustc_attr_parsing/src/lib.rs
+++ b/compiler/rustc_attr_parsing/src/lib.rs
@@ -80,7 +80,6 @@
 #![doc(rust_logo)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 #[macro_use]
diff --git a/compiler/rustc_baked_icu_data/src/lib.rs b/compiler/rustc_baked_icu_data/src/lib.rs
index f86a9db61c600..df9bee0ebf518 100644
--- a/compiler/rustc_baked_icu_data/src/lib.rs
+++ b/compiler/rustc_baked_icu_data/src/lib.rs
@@ -23,9 +23,9 @@
 // tidy-alphabetical-start
 #![allow(elided_lifetimes_in_paths)]
 #![allow(internal_features)]
+#![allow(unreachable_pub)] // because this crate is mostly generated code
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-// #![warn(unreachable_pub)] // don't use because this crate is mostly generated code
 // tidy-alphabetical-end
 
 mod data {
diff --git a/compiler/rustc_borrowck/src/lib.rs b/compiler/rustc_borrowck/src/lib.rs
index 68e0ab0933e61..780dc0d81e45e 100644
--- a/compiler/rustc_borrowck/src/lib.rs
+++ b/compiler/rustc_borrowck/src/lib.rs
@@ -13,7 +13,6 @@
 #![feature(rustdoc_internals)]
 #![feature(stmt_expr_attributes)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::borrow::Cow;
diff --git a/compiler/rustc_builtin_macros/src/lib.rs b/compiler/rustc_builtin_macros/src/lib.rs
index ca16583a45de7..c23ce1e5e4a2f 100644
--- a/compiler/rustc_builtin_macros/src/lib.rs
+++ b/compiler/rustc_builtin_macros/src/lib.rs
@@ -18,7 +18,6 @@
 #![feature(rustdoc_internals)]
 #![feature(string_from_utf8_lossy_owned)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate proc_macro;
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 8f72307eeba3d..d51532b3898ba 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -19,7 +19,6 @@
 #![feature(rustdoc_internals)]
 #![feature(slice_as_array)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::any::Any;
diff --git a/compiler/rustc_codegen_ssa/src/lib.rs b/compiler/rustc_codegen_ssa/src/lib.rs
index 4e758bfdec394..8ad040324147f 100644
--- a/compiler/rustc_codegen_ssa/src/lib.rs
+++ b/compiler/rustc_codegen_ssa/src/lib.rs
@@ -14,7 +14,6 @@
 #![feature(rustdoc_internals)]
 #![feature(trait_alias)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 //! This crate contains codegen code that is used by all codegen backends (LLVM and others).
diff --git a/compiler/rustc_const_eval/src/lib.rs b/compiler/rustc_const_eval/src/lib.rs
index ed5489652fba6..da52d60ae59fd 100644
--- a/compiler/rustc_const_eval/src/lib.rs
+++ b/compiler/rustc_const_eval/src/lib.rs
@@ -16,7 +16,6 @@
 #![feature(unqualified_local_imports)]
 #![feature(yeet_expr)]
 #![warn(unqualified_local_imports)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod check_consts;
diff --git a/compiler/rustc_data_structures/src/graph/tests.rs b/compiler/rustc_data_structures/src/graph/tests.rs
index b69b9dbc4a8e6..e48b9686c260f 100644
--- a/compiler/rustc_data_structures/src/graph/tests.rs
+++ b/compiler/rustc_data_structures/src/graph/tests.rs
@@ -3,7 +3,7 @@ use std::cmp::max;
 use super::*;
 use crate::fx::FxHashMap;
 
-pub struct TestGraph {
+pub(super) struct TestGraph {
     num_nodes: usize,
     start_node: usize,
     successors: FxHashMap<usize, Vec<usize>>,
@@ -11,7 +11,7 @@ pub struct TestGraph {
 }
 
 impl TestGraph {
-    pub fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
+    pub(super) fn new(start_node: usize, edges: &[(usize, usize)]) -> Self {
         let mut graph = TestGraph {
             num_nodes: start_node + 1,
             start_node,
diff --git a/compiler/rustc_data_structures/src/obligation_forest/mod.rs b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
index 78d69a66edc8b..8d19fc5f9ccf1 100644
--- a/compiler/rustc_data_structures/src/obligation_forest/mod.rs
+++ b/compiler/rustc_data_structures/src/obligation_forest/mod.rs
@@ -313,7 +313,7 @@ pub struct Error<O, E> {
 
 mod helper {
     use super::*;
-    pub type ObligationTreeIdGenerator = impl Iterator<Item = ObligationTreeId>;
+    pub(super) type ObligationTreeIdGenerator = impl Iterator<Item = ObligationTreeId>;
     impl<O: ForestObligation> ObligationForest<O> {
         pub fn new() -> ObligationForest<O> {
             ObligationForest {
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index a1cc75c498503..616a18a72ab7e 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -88,7 +88,7 @@ mod mode {
 
     // Whether thread safety might be enabled.
     #[inline]
-    pub fn might_be_dyn_thread_safe() -> bool {
+    pub(super) fn might_be_dyn_thread_safe() -> bool {
         DYN_THREAD_SAFE_MODE.load(Ordering::Relaxed) != DYN_NOT_THREAD_SAFE
     }
 
diff --git a/compiler/rustc_data_structures/src/sync/parallel.rs b/compiler/rustc_data_structures/src/sync/parallel.rs
index 1ba631b862376..8ef8a3f358569 100644
--- a/compiler/rustc_data_structures/src/sync/parallel.rs
+++ b/compiler/rustc_data_structures/src/sync/parallel.rs
@@ -46,7 +46,7 @@ pub fn parallel_guard<R>(f: impl FnOnce(&ParallelGuard) -> R) -> R {
     ret
 }
 
-pub fn serial_join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
+fn serial_join<A, B, RA, RB>(oper_a: A, oper_b: B) -> (RA, RB)
 where
     A: FnOnce() -> RA,
     B: FnOnce() -> RB,
diff --git a/compiler/rustc_data_structures/src/tagged_ptr/tests.rs b/compiler/rustc_data_structures/src/tagged_ptr/tests.rs
index 9c1e4cefa6923..85b21a7c8ecdf 100644
--- a/compiler/rustc_data_structures/src/tagged_ptr/tests.rs
+++ b/compiler/rustc_data_structures/src/tagged_ptr/tests.rs
@@ -7,7 +7,7 @@ use crate::stable_hasher::{HashStable, StableHasher};
 
 /// A tag type used in [`TaggedRef`] tests.
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
-pub enum Tag2 {
+enum Tag2 {
     B00 = 0b00,
     B01 = 0b01,
     B10 = 0b10,
diff --git a/compiler/rustc_driver_impl/src/lib.rs b/compiler/rustc_driver_impl/src/lib.rs
index a2ddff7183e60..6e4020c6eca18 100644
--- a/compiler/rustc_driver_impl/src/lib.rs
+++ b/compiler/rustc_driver_impl/src/lib.rs
@@ -16,7 +16,6 @@
 #![feature(result_flattening)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cmp::max;
diff --git a/compiler/rustc_error_codes/src/lib.rs b/compiler/rustc_error_codes/src/lib.rs
index 098ca42be2b44..2ddd03218c366 100644
--- a/compiler/rustc_error_codes/src/lib.rs
+++ b/compiler/rustc_error_codes/src/lib.rs
@@ -6,7 +6,6 @@
 #![deny(rustdoc::invalid_codeblock_attributes)]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 // This higher-order macro defines the error codes that are in use. It is used
diff --git a/compiler/rustc_error_messages/src/lib.rs b/compiler/rustc_error_messages/src/lib.rs
index ba1c3e185c2d9..a6fbbb29ccd3c 100644
--- a/compiler/rustc_error_messages/src/lib.rs
+++ b/compiler/rustc_error_messages/src/lib.rs
@@ -4,7 +4,6 @@
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(type_alias_impl_trait)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::borrow::Cow;
diff --git a/compiler/rustc_errors/src/lib.rs b/compiler/rustc_errors/src/lib.rs
index f2b133f56773b..f03e6755fabef 100644
--- a/compiler/rustc_errors/src/lib.rs
+++ b/compiler/rustc_errors/src/lib.rs
@@ -24,7 +24,6 @@
 #![feature(trait_alias)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate self as rustc_errors;
diff --git a/compiler/rustc_expand/src/lib.rs b/compiler/rustc_expand/src/lib.rs
index 777044e3f33bf..4222c9fe90616 100644
--- a/compiler/rustc_expand/src/lib.rs
+++ b/compiler/rustc_expand/src/lib.rs
@@ -13,7 +13,6 @@
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate proc_macro as pm;
diff --git a/compiler/rustc_feature/src/lib.rs b/compiler/rustc_feature/src/lib.rs
index 0b034a2ae1075..25764755a8fc9 100644
--- a/compiler/rustc_feature/src/lib.rs
+++ b/compiler/rustc_feature/src/lib.rs
@@ -15,7 +15,6 @@
 #![allow(internal_features)]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod accepted;
diff --git a/compiler/rustc_fluent_macro/src/lib.rs b/compiler/rustc_fluent_macro/src/lib.rs
index 3ad51fa1e64d0..c6e0484b92106 100644
--- a/compiler/rustc_fluent_macro/src/lib.rs
+++ b/compiler/rustc_fluent_macro/src/lib.rs
@@ -7,7 +7,6 @@
 #![feature(proc_macro_span)]
 #![feature(rustdoc_internals)]
 #![feature(track_path)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use proc_macro::TokenStream;
diff --git a/compiler/rustc_graphviz/src/lib.rs b/compiler/rustc_graphviz/src/lib.rs
index b5774f64b66b2..c8f8fd5be0237 100644
--- a/compiler/rustc_graphviz/src/lib.rs
+++ b/compiler/rustc_graphviz/src/lib.rs
@@ -277,7 +277,6 @@
 )]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::borrow::Cow;
diff --git a/compiler/rustc_hir/src/lib.rs b/compiler/rustc_hir/src/lib.rs
index 270d4fbec30f8..84d369f1eddb2 100644
--- a/compiler/rustc_hir/src/lib.rs
+++ b/compiler/rustc_hir/src/lib.rs
@@ -13,7 +13,6 @@
 #![feature(never_type)]
 #![feature(rustc_attrs)]
 #![feature(variant_count)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate self as rustc_hir;
diff --git a/compiler/rustc_hir_analysis/src/lib.rs b/compiler/rustc_hir_analysis/src/lib.rs
index cf18bab950ae2..170c6ac90630e 100644
--- a/compiler/rustc_hir_analysis/src/lib.rs
+++ b/compiler/rustc_hir_analysis/src/lib.rs
@@ -73,7 +73,6 @@ This API is completely unstable and subject to change.
 #![feature(slice_partition_dedup)]
 #![feature(try_blocks)]
 #![feature(unwrap_infallible)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 // These are used by Clippy.
diff --git a/compiler/rustc_hir_pretty/src/lib.rs b/compiler/rustc_hir_pretty/src/lib.rs
index 22edc18d71ca3..a9b36bf9fae90 100644
--- a/compiler/rustc_hir_pretty/src/lib.rs
+++ b/compiler/rustc_hir_pretty/src/lib.rs
@@ -3,7 +3,6 @@
 
 // tidy-alphabetical-start
 #![recursion_limit = "256"]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cell::Cell;
diff --git a/compiler/rustc_hir_typeck/src/lib.rs b/compiler/rustc_hir_typeck/src/lib.rs
index 8b9c2b4a6ca0f..263fb84206e0b 100644
--- a/compiler/rustc_hir_typeck/src/lib.rs
+++ b/compiler/rustc_hir_typeck/src/lib.rs
@@ -8,7 +8,6 @@
 #![feature(let_chains)]
 #![feature(never_type)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod _match;
diff --git a/compiler/rustc_incremental/src/lib.rs b/compiler/rustc_incremental/src/lib.rs
index 563ed7614c609..299ee4876389c 100644
--- a/compiler/rustc_incremental/src/lib.rs
+++ b/compiler/rustc_incremental/src/lib.rs
@@ -7,7 +7,6 @@
 #![doc(rust_logo)]
 #![feature(file_buffered)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod assert_dep_graph;
diff --git a/compiler/rustc_index/src/lib.rs b/compiler/rustc_index/src/lib.rs
index 3441a5f65c785..cc680838e7e7b 100644
--- a/compiler/rustc_index/src/lib.rs
+++ b/compiler/rustc_index/src/lib.rs
@@ -4,7 +4,6 @@
 #![cfg_attr(feature = "nightly", feature(extend_one, step_trait, test))]
 #![cfg_attr(feature = "nightly", feature(new_range_api))]
 #![cfg_attr(feature = "nightly", feature(new_zeroed_alloc))]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod bit_set;
diff --git a/compiler/rustc_index_macros/src/newtype.rs b/compiler/rustc_index_macros/src/newtype.rs
index 67ec776113399..f0b58eabbff9a 100644
--- a/compiler/rustc_index_macros/src/newtype.rs
+++ b/compiler/rustc_index_macros/src/newtype.rs
@@ -305,7 +305,7 @@ impl Parse for Newtype {
     }
 }
 
-pub fn newtype(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+pub(crate) fn newtype(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let input = parse_macro_input!(input as Newtype);
     input.0.into()
 }
diff --git a/compiler/rustc_infer/src/lib.rs b/compiler/rustc_infer/src/lib.rs
index a04b2bb2b08b5..ece18f4ea64ee 100644
--- a/compiler/rustc_infer/src/lib.rs
+++ b/compiler/rustc_infer/src/lib.rs
@@ -24,7 +24,6 @@
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
 #![recursion_limit = "512"] // For rustdoc
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod errors;
diff --git a/compiler/rustc_interface/src/lib.rs b/compiler/rustc_interface/src/lib.rs
index 54cd341698f0b..67e0be93523d9 100644
--- a/compiler/rustc_interface/src/lib.rs
+++ b/compiler/rustc_interface/src/lib.rs
@@ -4,7 +4,6 @@
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod callbacks;
diff --git a/compiler/rustc_lexer/src/lib.rs b/compiler/rustc_lexer/src/lib.rs
index bf18845a0830d..61638e45253fd 100644
--- a/compiler/rustc_lexer/src/lib.rs
+++ b/compiler/rustc_lexer/src/lib.rs
@@ -23,7 +23,6 @@
 // We want to be able to build this crate with a stable compiler,
 // so no `#![feature]` attributes should be added.
 #![deny(unstable_features)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod cursor;
diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs
index 5c5b3b350dd43..74c1ccf0dfd2b 100644
--- a/compiler/rustc_lint/src/lib.rs
+++ b/compiler/rustc_lint/src/lib.rs
@@ -32,7 +32,6 @@
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod async_closures;
diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs
index e564235c41a5e..46b4b1d438386 100644
--- a/compiler/rustc_lint_defs/src/lib.rs
+++ b/compiler/rustc_lint_defs/src/lib.rs
@@ -1,7 +1,3 @@
-// tidy-alphabetical-start
-#![warn(unreachable_pub)]
-// tidy-alphabetical-end
-
 use rustc_abi::ExternAbi;
 use rustc_ast::AttrId;
 use rustc_ast::attr::AttributeExt;
diff --git a/compiler/rustc_llvm/src/lib.rs b/compiler/rustc_llvm/src/lib.rs
index eda9b2b1fc092..68058250a2671 100644
--- a/compiler/rustc_llvm/src/lib.rs
+++ b/compiler/rustc_llvm/src/lib.rs
@@ -4,7 +4,6 @@
 #![doc(rust_logo)]
 #![feature(extern_types)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cell::RefCell;
diff --git a/compiler/rustc_macros/src/lib.rs b/compiler/rustc_macros/src/lib.rs
index 34fc0f00320c0..44ba064dd824c 100644
--- a/compiler/rustc_macros/src/lib.rs
+++ b/compiler/rustc_macros/src/lib.rs
@@ -6,7 +6,6 @@
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_span)]
 #![feature(proc_macro_tracked_env)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use proc_macro::TokenStream;
diff --git a/compiler/rustc_metadata/src/lib.rs b/compiler/rustc_metadata/src/lib.rs
index ebcc0efd5a67a..8898c5824fa25 100644
--- a/compiler/rustc_metadata/src/lib.rs
+++ b/compiler/rustc_metadata/src/lib.rs
@@ -15,7 +15,6 @@
 #![feature(proc_macro_internals)]
 #![feature(rustdoc_internals)]
 #![feature(trusted_len)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate proc_macro;
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index 48ea7df5c23fd..8fe2cc7101ba3 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -61,7 +61,6 @@
 #![feature(try_trait_v2_yeet)]
 #![feature(type_alias_impl_trait)]
 #![feature(yeet_expr)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 #[cfg(test)]
diff --git a/compiler/rustc_mir_build/src/lib.rs b/compiler/rustc_mir_build/src/lib.rs
index fa5db32d9134c..8e96d46dac272 100644
--- a/compiler/rustc_mir_build/src/lib.rs
+++ b/compiler/rustc_mir_build/src/lib.rs
@@ -8,7 +8,6 @@
 #![feature(if_let_guard)]
 #![feature(let_chains)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 // The `builder` module used to be named `build`, but that was causing GitHub's
diff --git a/compiler/rustc_mir_dataflow/src/lib.rs b/compiler/rustc_mir_dataflow/src/lib.rs
index a8a56baa1ffc0..a0efc623b8e7e 100644
--- a/compiler/rustc_mir_dataflow/src/lib.rs
+++ b/compiler/rustc_mir_dataflow/src/lib.rs
@@ -7,7 +7,6 @@
 #![feature(let_chains)]
 #![feature(never_type)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_middle::ty;
diff --git a/compiler/rustc_mir_transform/src/lib.rs b/compiler/rustc_mir_transform/src/lib.rs
index 04c9375b83176..73fdc42c67d65 100644
--- a/compiler/rustc_mir_transform/src/lib.rs
+++ b/compiler/rustc_mir_transform/src/lib.rs
@@ -12,7 +12,6 @@
 #![feature(never_type)]
 #![feature(try_blocks)]
 #![feature(yeet_expr)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use hir::ConstContext;
diff --git a/compiler/rustc_monomorphize/src/lib.rs b/compiler/rustc_monomorphize/src/lib.rs
index 714b64b3a231c..8f6914f3d7242 100644
--- a/compiler/rustc_monomorphize/src/lib.rs
+++ b/compiler/rustc_monomorphize/src/lib.rs
@@ -4,7 +4,6 @@
 #![feature(if_let_guard)]
 #![feature(impl_trait_in_assoc_type)]
 #![feature(let_chains)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_hir::lang_items::LangItem;
diff --git a/compiler/rustc_next_trait_solver/src/lib.rs b/compiler/rustc_next_trait_solver/src/lib.rs
index d67ae2550d967..f6963a790675f 100644
--- a/compiler/rustc_next_trait_solver/src/lib.rs
+++ b/compiler/rustc_next_trait_solver/src/lib.rs
@@ -6,7 +6,6 @@
 
 // tidy-alphabetical-start
 #![allow(rustc::usage_of_type_ir_inherent)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod canonicalizer;
diff --git a/compiler/rustc_parse/src/lib.rs b/compiler/rustc_parse/src/lib.rs
index 1a104ff5e3375..2edc8c83017d8 100644
--- a/compiler/rustc_parse/src/lib.rs
+++ b/compiler/rustc_parse/src/lib.rs
@@ -12,7 +12,6 @@
 #![feature(iter_intersperse)]
 #![feature(let_chains)]
 #![feature(string_from_utf8_lossy_owned)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::path::{Path, PathBuf};
diff --git a/compiler/rustc_parse_format/src/lib.rs b/compiler/rustc_parse_format/src/lib.rs
index 3b985621b5772..287bd8678da25 100644
--- a/compiler/rustc_parse_format/src/lib.rs
+++ b/compiler/rustc_parse_format/src/lib.rs
@@ -13,7 +13,6 @@
     html_playground_url = "https://play.rust-lang.org/",
     test(attr(deny(warnings)))
 )]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub use Alignment::*;
diff --git a/compiler/rustc_passes/src/lib.rs b/compiler/rustc_passes/src/lib.rs
index 1aa077ad2bb57..93ff0f66d695b 100644
--- a/compiler/rustc_passes/src/lib.rs
+++ b/compiler/rustc_passes/src/lib.rs
@@ -12,7 +12,6 @@
 #![feature(map_try_insert)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_middle::query::Providers;
diff --git a/compiler/rustc_pattern_analysis/src/lib.rs b/compiler/rustc_pattern_analysis/src/lib.rs
index a3400ebb79937..eeea724a29b45 100644
--- a/compiler/rustc_pattern_analysis/src/lib.rs
+++ b/compiler/rustc_pattern_analysis/src/lib.rs
@@ -6,7 +6,6 @@
 #![allow(rustc::diagnostic_outside_of_impl)]
 #![allow(rustc::untranslatable_diagnostic)]
 #![cfg_attr(feature = "rustc", feature(let_chains))]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod constructor;
diff --git a/compiler/rustc_pattern_analysis/tests/common/mod.rs b/compiler/rustc_pattern_analysis/tests/common/mod.rs
index 365bc2d863f47..8980b644f59b1 100644
--- a/compiler/rustc_pattern_analysis/tests/common/mod.rs
+++ b/compiler/rustc_pattern_analysis/tests/common/mod.rs
@@ -5,7 +5,7 @@ use rustc_pattern_analysis::usefulness::{PlaceValidity, UsefulnessReport};
 use rustc_pattern_analysis::{MatchArm, PatCx, PrivateUninhabitedField};
 
 /// Sets up `tracing` for easier debugging. Tries to look like the `rustc` setup.
-pub fn init_tracing() {
+fn init_tracing() {
     use tracing_subscriber::Layer;
     use tracing_subscriber::layer::SubscriberExt;
     use tracing_subscriber::util::SubscriberInitExt;
@@ -24,7 +24,7 @@ pub fn init_tracing() {
 /// A simple set of types.
 #[allow(dead_code)]
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
-pub enum Ty {
+pub(super) enum Ty {
     /// Booleans
     Bool,
     /// 8-bit unsigned integers
@@ -41,7 +41,7 @@ pub enum Ty {
 
 /// The important logic.
 impl Ty {
-    pub fn sub_tys(&self, ctor: &Constructor<Cx>) -> Vec<Self> {
+    pub(super) fn sub_tys(&self, ctor: &Constructor<Cx>) -> Vec<Self> {
         use Constructor::*;
         match (ctor, *self) {
             (Struct, Ty::Tuple(tys)) => tys.iter().copied().collect(),
@@ -63,7 +63,7 @@ impl Ty {
         }
     }
 
-    pub fn ctor_set(&self) -> ConstructorSet<Cx> {
+    fn ctor_set(&self) -> ConstructorSet<Cx> {
         match *self {
             Ty::Bool => ConstructorSet::Bool,
             Ty::U8 => ConstructorSet::Integers {
@@ -104,7 +104,7 @@ impl Ty {
         }
     }
 
-    pub fn write_variant_name(
+    fn write_variant_name(
         &self,
         f: &mut std::fmt::Formatter<'_>,
         ctor: &Constructor<Cx>,
@@ -120,7 +120,7 @@ impl Ty {
 }
 
 /// Compute usefulness in our simple context (and set up tracing for easier debugging).
-pub fn compute_match_usefulness<'p>(
+pub(super) fn compute_match_usefulness<'p>(
     arms: &[MatchArm<'p, Cx>],
     ty: Ty,
     scrut_validity: PlaceValidity,
@@ -137,7 +137,7 @@ pub fn compute_match_usefulness<'p>(
 }
 
 #[derive(Debug)]
-pub struct Cx;
+pub(super) struct Cx;
 
 /// The context for pattern analysis. Forwards anything interesting to `Ty` methods.
 impl PatCx for Cx {
diff --git a/compiler/rustc_privacy/src/lib.rs b/compiler/rustc_privacy/src/lib.rs
index 5271d03a6f617..5e3e8d69b6031 100644
--- a/compiler/rustc_privacy/src/lib.rs
+++ b/compiler/rustc_privacy/src/lib.rs
@@ -6,7 +6,6 @@
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
 #![feature(try_blocks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod errors;
diff --git a/compiler/rustc_query_impl/src/lib.rs b/compiler/rustc_query_impl/src/lib.rs
index 73c205fdb17d1..40da46a027dfe 100644
--- a/compiler/rustc_query_impl/src/lib.rs
+++ b/compiler/rustc_query_impl/src/lib.rs
@@ -8,7 +8,6 @@
 #![feature(min_specialization)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_data_structures::stable_hasher::HashStable;
diff --git a/compiler/rustc_query_system/src/lib.rs b/compiler/rustc_query_system/src/lib.rs
index ee984095ad84b..a546362414cf4 100644
--- a/compiler/rustc_query_system/src/lib.rs
+++ b/compiler/rustc_query_system/src/lib.rs
@@ -6,7 +6,6 @@
 #![feature(hash_raw_entry)]
 #![feature(let_chains)]
 #![feature(min_specialization)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod cache;
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index 4c5d4041022a9..40e44f3ec7374 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -20,7 +20,6 @@
 #![feature(let_chains)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::cell::{Cell, RefCell};
diff --git a/compiler/rustc_sanitizers/src/lib.rs b/compiler/rustc_sanitizers/src/lib.rs
index 55be931bcd6d4..e4792563e71ea 100644
--- a/compiler/rustc_sanitizers/src/lib.rs
+++ b/compiler/rustc_sanitizers/src/lib.rs
@@ -5,7 +5,6 @@
 
 // tidy-alphabetical-start
 #![feature(let_chains)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod cfi;
diff --git a/compiler/rustc_serialize/src/lib.rs b/compiler/rustc_serialize/src/lib.rs
index 9e9b78cfdd57c..13c1a273eb816 100644
--- a/compiler/rustc_serialize/src/lib.rs
+++ b/compiler/rustc_serialize/src/lib.rs
@@ -14,7 +14,6 @@
 #![feature(min_specialization)]
 #![feature(never_type)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub use self::serialize::{Decodable, Decoder, Encodable, Encoder};
diff --git a/compiler/rustc_session/src/lib.rs b/compiler/rustc_session/src/lib.rs
index 112adde3740bc..43657eaa8c4dc 100644
--- a/compiler/rustc_session/src/lib.rs
+++ b/compiler/rustc_session/src/lib.rs
@@ -6,7 +6,6 @@
 // To generate CodegenOptionsTargetModifiers and UnstableOptionsTargetModifiers enums
 // with macro_rules, it is necessary to use recursive mechanic ("Incremental TT Munchers").
 #![recursion_limit = "256"]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod errors;
diff --git a/compiler/rustc_smir/src/lib.rs b/compiler/rustc_smir/src/lib.rs
index 2215e2f01ade0..9f88887530614 100644
--- a/compiler/rustc_smir/src/lib.rs
+++ b/compiler/rustc_smir/src/lib.rs
@@ -15,7 +15,6 @@
 )]
 #![doc(rust_logo)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub mod rustc_internal;
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index bca9323a50d4c..6e9d92edb7b55 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -32,7 +32,6 @@
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
 #![feature(slice_as_chunks)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 // The code produced by the `Encodable`/`Decodable` derive macros refer to
diff --git a/compiler/rustc_symbol_mangling/src/lib.rs b/compiler/rustc_symbol_mangling/src/lib.rs
index 4312c82815c16..269401ef3a2de 100644
--- a/compiler/rustc_symbol_mangling/src/lib.rs
+++ b/compiler/rustc_symbol_mangling/src/lib.rs
@@ -93,7 +93,6 @@
 #![doc(rust_logo)]
 #![feature(let_chains)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_hir::def::DefKind;
diff --git a/compiler/rustc_target/src/lib.rs b/compiler/rustc_target/src/lib.rs
index 7ebe96960ed0f..a8d7da5692de4 100644
--- a/compiler/rustc_target/src/lib.rs
+++ b/compiler/rustc_target/src/lib.rs
@@ -16,7 +16,6 @@
 #![feature(let_chains)]
 #![feature(rustc_attrs)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use std::path::{Path, PathBuf};
diff --git a/compiler/rustc_trait_selection/src/lib.rs b/compiler/rustc_trait_selection/src/lib.rs
index b235d0da83cca..b18fb0fb8fd31 100644
--- a/compiler/rustc_trait_selection/src/lib.rs
+++ b/compiler/rustc_trait_selection/src/lib.rs
@@ -31,7 +31,6 @@
 #![feature(unwrap_infallible)]
 #![feature(yeet_expr)]
 #![recursion_limit = "512"] // For rustdoc
-#![warn(unreachable_pub)] // For rustdoc
 // tidy-alphabetical-end
 
 pub mod error_reporting;
diff --git a/compiler/rustc_traits/src/lib.rs b/compiler/rustc_traits/src/lib.rs
index d2f979bd6d9dc..697c839180312 100644
--- a/compiler/rustc_traits/src/lib.rs
+++ b/compiler/rustc_traits/src/lib.rs
@@ -2,7 +2,6 @@
 
 // tidy-alphabetical-start
 #![recursion_limit = "256"]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 mod codegen;
diff --git a/compiler/rustc_transmute/src/lib.rs b/compiler/rustc_transmute/src/lib.rs
index 81a11f7cfb267..00928137d2976 100644
--- a/compiler/rustc_transmute/src/lib.rs
+++ b/compiler/rustc_transmute/src/lib.rs
@@ -1,6 +1,5 @@
 // tidy-alphabetical-start
 #![feature(never_type)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 pub(crate) use rustc_data_structures::fx::{FxIndexMap as Map, FxIndexSet as Set};
diff --git a/compiler/rustc_ty_utils/src/lib.rs b/compiler/rustc_ty_utils/src/lib.rs
index 8be1611bb9ac2..35cc6f3985652 100644
--- a/compiler/rustc_ty_utils/src/lib.rs
+++ b/compiler/rustc_ty_utils/src/lib.rs
@@ -16,7 +16,6 @@
 #![feature(let_chains)]
 #![feature(never_type)]
 #![feature(rustdoc_internals)]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 use rustc_middle::query::Providers;
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index 15ef4e7d6c1d2..e2dfd9173fab8 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -6,7 +6,6 @@
     feature(associated_type_defaults, never_type, rustc_attrs, negative_impls)
 )]
 #![cfg_attr(feature = "nightly", allow(internal_features))]
-#![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
 extern crate self as rustc_type_ir;
diff --git a/src/bootstrap/src/bin/rustc.rs b/src/bootstrap/src/bin/rustc.rs
index 6104506759282..92b104b163e3f 100644
--- a/src/bootstrap/src/bin/rustc.rs
+++ b/src/bootstrap/src/bin/rustc.rs
@@ -21,8 +21,8 @@ use std::process::{Child, Command};
 use std::time::Instant;
 
 use shared_helpers::{
-    dylib_path, dylib_path_var, exe, maybe_dump, parse_rustc_stage, parse_rustc_verbose,
-    parse_value_from_args,
+    FLAGS_FOR_RUSTC, dylib_path, dylib_path_var, exe, maybe_dump, parse_rustc_stage,
+    parse_rustc_verbose, parse_value_from_args,
 };
 
 #[path = "../utils/shared_helpers.rs"]
@@ -145,6 +145,35 @@ fn main() {
         cmd.arg("-Z").arg("on-broken-pipe=kill");
     }
 
+    // In `cargo.rs` we add the `FLAGS_FOR_RUSTC` flags for all `compiler/`
+    // crates to RUSTFLAGS. However, RUSTFLAGS is ignored for `compiler/` proc
+    // macro crates, because RUSTFLAGS is ignored when `--target` is given. So,
+    // we add the `FLAGS_FOR_RUSTC` flags directly to the command here if they
+    // are also in RUSTFLAGS.
+    let crate_type = parse_value_from_args(&orig_args, "--crate-type");
+    if crate_type == Some("proc-macro") {
+        if let Ok(rustflags) = env::var("RUSTFLAGS") {
+            // Count how many of flags from `FLAGS_FOR_RUSTC` are in RUSTFLAGS.
+            let n = FLAGS_FOR_RUSTC.iter().filter(|&flag| rustflags.contains(flag)).count();
+            if n == FLAGS_FOR_RUSTC.len() {
+                // All the FLAGS_FOR_RUSTC flags are in RUSTFLAGS, which means
+                // this is a `compiler/` proc macro crate. Insert the flags
+                // directly into the command.
+                for flag in shared_helpers::FLAGS_FOR_RUSTC {
+                    cmd.arg(flag);
+                }
+            } else if n == 0 {
+                // None of the FLAGS_FOR_RUSTC flags are in RUSTFLAGS.
+                // Therefore it's a non-`compiler/` proc macro crate:
+                // third-party, clippy, etc. Do nothing.
+            } else {
+                // Some but not all of the FLAGS_FOR_RUSTC flags are in
+                // RUSTFLAGS. Huh?
+                panic!("RUSTFLAGS is missing some expected flags");
+            }
+        }
+    }
+
     if target.is_some() {
         // The stage0 compiler has a special sysroot distinct from what we
         // actually downloaded, so we just always pass the `--sysroot` option,
@@ -165,7 +194,6 @@ fn main() {
             cmd.arg("-C").arg("panic=abort");
         }
 
-        let crate_type = parse_value_from_args(&orig_args, "--crate-type");
         // `-Ztls-model=initial-exec` must not be applied to proc-macros, see
         // issue https://github.com/rust-lang/rust/issues/100530
         if env::var("RUSTC_TLS_MODEL_INITIAL_EXEC").is_ok()
diff --git a/src/bootstrap/src/core/builder/cargo.rs b/src/bootstrap/src/core/builder/cargo.rs
index d1d52d82eaa0f..180812cfa8d4b 100644
--- a/src/bootstrap/src/core/builder/cargo.rs
+++ b/src/bootstrap/src/core/builder/cargo.rs
@@ -1071,13 +1071,13 @@ impl Builder<'_> {
             rustdocflags.arg("-Wrustdoc::invalid_codeblock_attributes");
         }
 
+        // Add some flags to RUSTFLAGS for `compiler/` crates. Note: proc macro
+        // crates need additional special handling. See the `FLAGS_FOR_RUSTC`
+        // use in `rustc.rs` for details.
         if mode == Mode::Rustc {
-            rustflags.arg("-Wrustc::internal");
-            rustflags.arg("-Drustc::symbol_intern_string_literal");
-            // FIXME(edition_2024): Change this to `-Wrust_2024_idioms` when all
-            // of the individual lints are satisfied.
-            rustflags.arg("-Wkeyword_idents_2024");
-            rustflags.arg("-Wunsafe_op_in_unsafe_fn");
+            for flag in crate::utils::shared_helpers::FLAGS_FOR_RUSTC {
+                rustflags.arg(flag);
+            }
         }
 
         if self.config.rust_frame_pointers {
diff --git a/src/bootstrap/src/utils/shared_helpers.rs b/src/bootstrap/src/utils/shared_helpers.rs
index 7b206c3ffe826..4f1ef6ef0176d 100644
--- a/src/bootstrap/src/utils/shared_helpers.rs
+++ b/src/bootstrap/src/utils/shared_helpers.rs
@@ -113,3 +113,14 @@ pub fn parse_value_from_args<'a>(args: &'a [OsString], key: &str) -> Option<&'a
 
     None
 }
+
+// Flags used to compile all crates in `compiler/`.
+pub const FLAGS_FOR_RUSTC: &[&'static str] = &[
+    "-Wrustc::internal",
+    "-Drustc::symbol_intern_string_literal",
+    // FIXME(edition_2024): Change this to `-Wrust_2024_idioms` when all of the
+    // individual lints are satisfied.
+    "-Wkeyword_idents_2024",
+    "-Wunreachable_pub",
+    "-Wunsafe_op_in_unsafe_fn",
+];