test(build-std): Add test for LTO#16277
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Would you mind briefly explaining (or copy) the regression a bit in the PR description as well?
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Would also be helpful to have a code comment around the test, as the test has a bit of distance from Cargo itself.
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Thanks for providing the context!
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Update cargo submodule 7 commits in 5c0343317ce45d2ec17ecf41eaa473a02d73e29c..9fa462fe3a81e07e0bfdcc75c29d312c55113ebb 2025-11-18 19:05:44 +0000 to 2025-11-21 20:49:51 +0000 - Enable CARGO_CFG_DEBUG_ASSERTIONS in build scripts based on profile (rust-lang/cargo#16160) - fix(config-include): disallow glob and template syntax (rust-lang/cargo#16285) - test(config-include): include always relative to including config (rust-lang/cargo#16286) - docs(guide): When suggesting alt dev profile, link to related issue (rust-lang/cargo#16275) - refactor(timings): separate data collection and presentation (rust-lang/cargo#16282) - test(build-std): Add test for LTO (rust-lang/cargo#16277) - fix(bindeps): do not propagate artifact dependency to proc macro or build deps (rust-lang/cargo#15788) r? ghost
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…to, r=jieyouxu test: Add a test for 146133 This is a test without using `-Zbuild-std` for rust-lang#146133. There is another test using `-Zbuild-std`: rust-lang/cargo#16277. Even if a crate is marked as `#![no_builtins]`, we can still generate bitcode for rlib, but we cannot emit bitcode to the linker in rustc's LTO.
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…to, r=jieyouxu test: Add a test for 146133 This is a test without using `-Zbuild-std` for rust-lang#146133. There is another test using `-Zbuild-std`: rust-lang/cargo#16277. Even if a crate is marked as `#![no_builtins]`, we can still generate bitcode for rlib, but we cannot emit bitcode to the linker in rustc's LTO.
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Rollup merge of #149772 - dianqk:no-builtins-linker-plugin-lto, r=jieyouxu test: Add a test for 146133 This is a test without using `-Zbuild-std` for #146133. There is another test using `-Zbuild-std`: rust-lang/cargo#16277. Even if a crate is marked as `#![no_builtins]`, we can still generate bitcode for rlib, but we cannot emit bitcode to the linker in rustc's LTO.
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Add a test for rust-lang/rust#146133.
cargo +nightly-2025-08-29 test --test build-std -- ltocan reproduce the regression.This is not a bug from Cargo, but it requires
-Zbuild-stdin most use cases.The test case is from rust-lang/rust#146109. The point is that when rustc is invoked with -Clto=fat or -Clto=thin, it should perform LTO with ALL bitcodes. However, rust-lang/rust#145368 emits bitcodes for compiler_builtins but excludes it from LTO participation.
As a result, the compiler_builtins bitcodes library is passed to the linker, but the linkers, such as the GNU ld or older versions of LLD, are unable to process bitcodes.