bootstrap: forward -fdebug-prefix-map when using cc by paradoxicalguy · Pull Request #159673 · rust-lang/rust

paradoxicalguy · 2026-07-21T17:11:00Z

the existing clang/gcc checks don't match on systems where self.cc(target) resolves to cc, so -fdebug-prefix-map isn't forwarded to the C compiler.

this leaves local checkout paths in compiler-builtins DWARF.
recognize cc as well so the remapping flag is forwarded. confirmed remap-path-prefix-std passes, and inspecting the generated DWARF to verify that checkout paths are remapped.

r? @Urgau
cc @bjorn3

Urgau · 2026-07-21T17:41:58Z

-            if cc.ends_with("clang") || cc.ends_with("gcc") {
+            if cc.ends_with("clang")
+                || cc.ends_with("gcc")
+                || cc.file_name().is_some_and(|f| f == "cc")


On my system, cc is just a symlink to gcc. Could we maybe resolve the symlink and check for clang/gcc?

View changes since the review

i instrumented it, and self.cc(target) is just cc rather than an absolute path (/usr/bin/cc.). so fs::canonicalize won't resolve it directly since it doesn't search PATH. do you have a preferred way to resolve the compiler first,
or is there already a helper in bootstrap that does this?

my shell:

which cc # /usr/bin/cc readlink -f "$(which cc)" # /usr/bin/x86_64-linux-gnu-gcc-13

Hum, that's annoying. Not sure what to do.

Urgau · 2026-07-21T20:44:31Z

I'm not sure I'm the best reviewer for this bootstrap change.

r? bootstrap

Kobzol · 2026-07-24T09:53:33Z

            let map = format!("{}={}", self.src.display(), map_to);
            let cc = self.cc(target);
-            if cc.ends_with("clang") || cc.ends_with("gcc") {
+            if cc.ends_with("clang")


This check is wrong anyway, you can have e.g. clang-18 or something. What about calling cc_tool instead and checking is_like_clang and is_like_gnu?

View changes since the review

if let Some(map_to) = self.debuginfo_map_to(which, RemapScheme::NonCompiler) { let map = format!("{}={}", self.src.display(), map_to); let cc = self.cc_tool(target); if cc.is_like_clang() || cc.is_like_gnu() { base.push(format!("-fdebug-prefix-map={map}")); } else if cc.is_like_clang_cl() { base.push("-Xclang".into()); base.push(format!("-fdebug-prefix-map={map}")); } } base

passes locally in stage 2 also :)

Kobzol · 2026-07-25T11:08:17Z

Even regardless of reproducibility, this is a good cleanup, thanks!

@bors r+

rust-bors · 2026-07-25T11:08:19Z

📌 Commit 99ff7d2 has been approved by Kobzol

It is now in the queue for this repository.

paradoxicalguy · 2026-07-25T11:18:24Z

yay :D

@Urgau

…, r=Kobzol bootstrap: forward -fdebug-prefix-map when using cc the existing `clang/gcc` checks don't match on systems where `self.cc(target)` resolves to `cc`, so `-fdebug-prefix-map` isn't forwarded to the `C` compiler. this leaves local checkout paths in `compiler-builtins DWARF`. recognize cc as well so the remapping flag is forwarded. confirmed `remap-path-prefix-std passes`, and inspecting the generated `DWARF` to verify that checkout paths are remapped. r? @Urgau cc @bjorn3

rust-bors · 2026-07-25T12:41:02Z

💔 Test for ef4e0b3 failed: CI

Kobzol · 2026-07-25T13:28:42Z

@bors retry Actions outage

rust-bors · 2026-07-25T14:26:23Z

⌛ Testing commit 99ff7d2 with merge b9f688a...

Workflow: https://github.com/rust-lang/rust/actions/runs/30161634838

@Urgau

…, r=Kobzol bootstrap: forward -fdebug-prefix-map when using cc the existing `clang/gcc` checks don't match on systems where `self.cc(target)` resolves to `cc`, so `-fdebug-prefix-map` isn't forwarded to the `C` compiler. this leaves local checkout paths in `compiler-builtins DWARF`. recognize cc as well so the remapping flag is forwarded. confirmed `remap-path-prefix-std passes`, and inspecting the generated `DWARF` to verify that checkout paths are remapped. r? @Urgau cc @bjorn3

@Urgau

…p-detection, r=Kobzol bootstrap: forward -fdebug-prefix-map when using cc the existing `clang/gcc` checks don't match on systems where `self.cc(target)` resolves to `cc`, so `-fdebug-prefix-map` isn't forwarded to the `C` compiler. this leaves local checkout paths in `compiler-builtins DWARF`. recognize cc as well so the remapping flag is forwarded. confirmed `remap-path-prefix-std passes`, and inspecting the generated `DWARF` to verify that checkout paths are remapped. r? @Urgau cc @bjorn3

GuillaumeGomez · 2026-07-25T14:28:53Z

Part of #159905.

@bors yield

rust-bors · 2026-07-25T14:29:01Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/30161634838

The next pull request likely to be tested is #159905.

Rollup of 23 pull requests Successful merges: - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159411 ([rustdoc] Correctly handle output options with --show-coverage) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`) - #159810 (Add tuple never coercion collection regression test) - #159826 (Remove redundant `#[rustc_paren_sugar]` feature gate) - #159853 (Updated expect messages for `CString` struct and method documentation) - #159878 (bootstrap: Remove obsolete option `build.compiletest-use-stage0-libtest`) - #159882 (Update expect messages in library/alloc/boxed.rs and library/alloc/string.rs to follow the style guide) - #159891 (Split multiline derives into std/rustc macros) - #159895 (rustc-dev-guide subtree update)

@Urgau

…p-detection, r=Kobzol bootstrap: forward -fdebug-prefix-map when using cc the existing `clang/gcc` checks don't match on systems where `self.cc(target)` resolves to `cc`, so `-fdebug-prefix-map` isn't forwarded to the `C` compiler. this leaves local checkout paths in `compiler-builtins DWARF`. recognize cc as well so the remapping flag is forwarded. confirmed `remap-path-prefix-std passes`, and inspecting the generated `DWARF` to verify that checkout paths are remapped. r? @Urgau cc @bjorn3

…uwer Rollup of 25 pull requests Successful merges: - #138618 (Support using const pointers in asm `const` operand) - #157962 (Lower paths to functions in const args as ConstKind::Error) - #158404 (trait_solver: normalize next-gen region constraints) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159174 (Fix implicit_provenance_casts warnings on Xous) - #159179 (enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group) - #159518 (iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>) - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159700 (Split non-local `semicolon_in_expressions_from_macros` into a separate lint) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159785 (Share _Unwind_Exception definition between native and wasm) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159695 (proc_macro: Fix cfg_attr inner attrs in file modules) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`)

@Urgau

…p-detection, r=Kobzol bootstrap: forward -fdebug-prefix-map when using cc the existing `clang/gcc` checks don't match on systems where `self.cc(target)` resolves to `cc`, so `-fdebug-prefix-map` isn't forwarded to the `C` compiler. this leaves local checkout paths in `compiler-builtins DWARF`. recognize cc as well so the remapping flag is forwarded. confirmed `remap-path-prefix-std passes`, and inspecting the generated `DWARF` to verify that checkout paths are remapped. r? @Urgau cc @bjorn3

…uwer Rollup of 25 pull requests Successful merges: - #159825 (codegen: handle OperandValue::Uninit in codegen_return_terminator) - #138618 (Support using const pointers in asm `const` operand) - #157962 (Lower paths to functions in const args as ConstKind::Error) - #158404 (trait_solver: normalize next-gen region constraints) - #158709 (rustdoc: warn on improperly interleaved HTML/MD) - #159174 (Fix implicit_provenance_casts warnings on Xous) - #159179 (enable `unreachable_cfg_select_predicates` lint as part of `unused` lint group) - #159518 (iter: extend step_by specialization to cover StepBy<RangeIter<{integer}>>) - #159673 (bootstrap: forward -fdebug-prefix-map when using cc) - #159700 (Split non-local `semicolon_in_expressions_from_macros` into a separate lint) - #159720 (document #[global_allocator] constraints) - #159732 (optimization: don't look for diagnostic/canonical items without rustc_attrs enabled) - #159738 (implement `CovariantUnsafeCell`) - #159740 (reuse regular exported_non_generic_symbols logic in Miri) - #159780 (check `extern "custom"` function pointers) - #159786 (rustdoc-js: ignore editor temp files in test folder discovery) - #159819 (std::sync::poison: disable auto_cfg on PoisonError::new) - #155388 (stepping into where-clauses during normalization may be productive) - #155914 (when bailing on ambiguity, don't force other results to ambig) - #159204 (Add support to caller_location to rustc_public) - #159439 (Fix(lib/fs/win): Fall back on Win32 delete for `Dir::remove_file`) - #159676 (Update wasm-component-ld to 0.5.27) - #159695 (proc_macro: Fix cfg_attr inner attrs in file modules) - #159730 (allow accessing the contents of UnsafeCell without going through get) - #159809 (Avoid `#[target_features]`)

rustbot assigned Urgau Jul 21, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-bootstrap Relevant to the bootstrap subteam: Rust's build system (x.py and src/bootstrap) labels Jul 21, 2026

Urgau reviewed Jul 21, 2026

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rustbot assigned Mark-Simulacrum and unassigned Urgau Jul 21, 2026

Kobzol reviewed Jul 24, 2026

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bootstrap: use cc::Tool for compiler detection.

99ff7d2

paradoxicalguy force-pushed the fix-cc-debuginfo-map-detection branch from 7c90cef to 99ff7d2 Compare July 25, 2026 09:43

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GuillaumeGomez mentioned this pull request Jul 25, 2026

Rollup of 23 pull requests #159905

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JonathanBrouwer mentioned this pull request Jul 25, 2026

Rollup of 25 pull requests #159920

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JonathanBrouwer mentioned this pull request Jul 25, 2026

Rollup of 25 pull requests #159926

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