cargo_build_script: propagate cdylib and binary link args#4097
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Thanks! Can you add a test for somewhere under //cargo/tests/cargo_build_script that confirms the new flags are behaving as expected for binary and library consumers?
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A build script's cargo::rustc-cdylib-link-arg and cargo::rustc-link-arg-bins directives were dropped with a warning, so flags like napi-rs's `-undefined dynamic_lookup` never reached the linker. Route them through BuildInfo to the targets cargo applies them to: * rustc-cdylib-link-arg is collected into BuildInfo.cdylib_link_flags and applied to cdylib crates. Matching cargo, it propagates transitively: a cdylib picks up the cdylib link args of every build script in its transitive dependencies (rust-lang/cargo#9562). * rustc-link-arg-bins is collected into BuildInfo.bin_link_flags and applied to binary crates. Each set is written to its own flag file, added to the relevant rustc action as an --arg-file, so a non-matching crate type never reads it. The per-binary cargo::rustc-link-arg-bin=BIN=FLAG stays unsupported: a build script's outputs are shared by every target that depends on it, so a flag cannot be scoped to one named binary. Fixes bazelbuild#1062.
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Thank you! Looking good! Just need to fix buildifier
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Fixes #1062.
A build script's
cargo::rustc-cdylib-link-argandcargo::rustc-link-arg-binswere dropped with a warning, so flags like napi-rs's-undefined dynamic_lookupnever reached the linker.Route them through
BuildInfoto the targets cargo applies them to:rustc-cdylib-link-arg→BuildInfo.cdylib_link_flags, applied to cdylib crates and propagated transitively (matching cargo, Tracking issue forrustc-cdylib-link-argtransitive warning rust-lang/cargo#9562).rustc-link-arg-bins→BuildInfo.bin_link_flags, applied to binary crates.Each set is written to its own flag file, added to the rustc action as an
--arg-file, so a non-matching crate type never reads it. The per-binaryrustc-link-arg-bin=BIN=FLAGstays unsupported — a build script's outputs are shared by every consumer, so a flag can't be scoped to one named binary.