Allow configuring arbitrary codegen backends #15562
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Rather than just builtin codegen backends. This is perma-unstable on the rustc side, but is useful to enable a codegen backend built separately from rustc to be used without overwriting RUSTFLAGS as well as to allow configuring the codegen backend on a per-package basis.
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bjorn3
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May 19, 2025
| name, | ||
| codegen_backend, | ||
| ); | ||
| } |
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If preferred I can also keep this check on the cargo side when nightly features are disabled.
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How arbitrary you'd like to have for codegen-backend name? What is the real use case here?
The change seems fine to me though, as a nightly feature.
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Basically -Zcodegen-backend allows either of the following:
- The name of a builtin codegen backend. This will eventually be stabilized once one of the non-LLVM backends gets stabilized.
- The full path to a dylib implementing a codegen backend. This will never be stable. It exists to allow codegen backends not shipped as part of rustc to be used. For example cg_clif uses it when you locally build it or when using the version from its CI rather than the rustup distributed version (the CI version is newer). Same for cg_gcc when you locally build it.
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Thanks for the info! It makes sense to relax it a bit for now.
When stabilization, Cargo should only allow a set of known backends. We should track it somewhere, though we dont really have a Cargo tracking issue for codegen-backend right now.
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weihanglo
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May 19, 2025
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Update cargo 9 commits in 47c911e9e6f6461f90ce19142031fe16876a3b95..68db37499f2de8acef704c73d9031be6fbcbaee4 2025-05-14 17:53:17 +0000 to 2025-05-22 14:27:15 +0000 - chore(gh): Add new-lint issue template (rust-lang/cargo#15575) - fix(toml): Remove workaround for rustc frontmatter support (rust-lang/cargo#15570) - fix(vendor)!: vendor files with .rej/.orig suffix (rust-lang/cargo#15569) - fix(vendor)!: direct extraction for registry sources (rust-lang/cargo#15514) - chore(deps): update msrv (1 version) to v1.87 (rust-lang/cargo#15530) - Fix comment for cargo/core/compiler/fingerprint/mod.rs (rust-lang/cargo#15565) - fix: remove unnecessary workaround in standard_lib test (rust-lang/cargo#15522) - Allow configuring arbitrary codegen backends (rust-lang/cargo#15562) - Update dependencies (rust-lang/cargo#15557) r? ghost
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Update cargo 9 commits in 47c911e9e6f6461f90ce19142031fe16876a3b95..68db37499f2de8acef704c73d9031be6fbcbaee4 2025-05-14 17:53:17 +0000 to 2025-05-22 14:27:15 +0000 - chore(gh): Add new-lint issue template (rust-lang/cargo#15575) - fix(toml): Remove workaround for rustc frontmatter support (rust-lang/cargo#15570) - fix(vendor)!: vendor files with .rej/.orig suffix (rust-lang/cargo#15569) - fix(vendor)!: direct extraction for registry sources (rust-lang/cargo#15514) - chore(deps): update msrv (1 version) to v1.87 (rust-lang/cargo#15530) - Fix comment for cargo/core/compiler/fingerprint/mod.rs (rust-lang/cargo#15565) - fix: remove unnecessary workaround in standard_lib test (rust-lang/cargo#15522) - Allow configuring arbitrary codegen backends (rust-lang/cargo#15562) - Update dependencies (rust-lang/cargo#15557) r? ghost
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Rather than just builtin codegen backends. This is perma-unstable on the rustc side, but is useful to enable a codegen backend built separately from rustc to be used without overwriting RUSTFLAGS as well as to allow configuring the codegen backend on a per-package basis.