Fix '--strategy=Rustc=local' with pipelined compilation#17
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…tc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions.
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* When '--strategy=Rustc=local' is used with pipelined compilation, rustc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions. (#17) * Add RUSTC_BOOTSTRAP guardrail for -Zno-codegen pipelining Injects RUSTC_BOOTSTRAP=1 + -Zallow-features= (empty list) on the metadata and full compile actions when pipelined_compilation is enabled on a stable/beta toolchain. The bootstrap env is required for -Zno-codegen on non-nightly rustc and must match across both actions for SVH compatibility. The empty allow-features list prevents the bootstrap env from silently unlocking #![feature(...)] in user code. Nightly toolchains skip both injections: unstable features are already allowed, and the guardrail would break legitimate #![feature(...)] usage. Escape hatch: if the user sets RUSTC_BOOTSTRAP in rustc_env / shell env or passes -Zallow-features=... via rustc_flags / extra_rustc_flag, rules_rust treats their configuration as authoritative and skips both injections. Tests: - //test/pipelining_bootstrap_gate: manual target that #![feature(trait_alias)] to validate E0725 fires on stable under the guardrail. - //test/unit/pipelined_compilation: guardrail_{baseline,user_env,user_flag, space_form,global_env,global_flag}_optout_test variants.
dzbarsky
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May 11, 2026
* When '--strategy=Rustc=local' is used with pipelined compilation, rustc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions. (#17) * Add RUSTC_BOOTSTRAP guardrail for -Zno-codegen pipelining Injects RUSTC_BOOTSTRAP=1 + -Zallow-features= (empty list) on the metadata and full compile actions when pipelined_compilation is enabled on a stable/beta toolchain. The bootstrap env is required for -Zno-codegen on non-nightly rustc and must match across both actions for SVH compatibility. The empty allow-features list prevents the bootstrap env from silently unlocking #![feature(...)] in user code. Nightly toolchains skip both injections: unstable features are already allowed, and the guardrail would break legitimate #![feature(...)] usage. Escape hatch: if the user sets RUSTC_BOOTSTRAP in rustc_env / shell env or passes -Zallow-features=... via rustc_flags / extra_rustc_flag, rules_rust treats their configuration as authoritative and skips both injections. Tests: - //test/pipelining_bootstrap_gate: manual target that #![feature(trait_alias)] to validate E0725 fires on stable under the guardrail. - //test/unit/pipelined_compilation: guardrail_{baseline,user_env,user_flag, space_form,global_env,global_flag}_optout_test variants.
dzbarsky
pushed a commit
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May 11, 2026
* When '--strategy=Rustc=local' is used with pipelined compilation, rustc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions. (#17) * Add RUSTC_BOOTSTRAP guardrail for -Zno-codegen pipelining Injects RUSTC_BOOTSTRAP=1 + -Zallow-features= (empty list) on the metadata and full compile actions when pipelined_compilation is enabled on a stable/beta toolchain. The bootstrap env is required for -Zno-codegen on non-nightly rustc and must match across both actions for SVH compatibility. The empty allow-features list prevents the bootstrap env from silently unlocking #![feature(...)] in user code. Nightly toolchains skip both injections: unstable features are already allowed, and the guardrail would break legitimate #![feature(...)] usage. Escape hatch: if the user sets RUSTC_BOOTSTRAP in rustc_env / shell env or passes -Zallow-features=... via rustc_flags / extra_rustc_flag, rules_rust treats their configuration as authoritative and skips both injections. Tests: - //test/pipelining_bootstrap_gate: manual target that #![feature(trait_alias)] to validate E0725 fires on stable under the guardrail. - //test/unit/pipelined_compilation: guardrail_{baseline,user_env,user_flag, space_form,global_env,global_flag}_optout_test variants.
dzbarsky
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May 15, 2026
* When '--strategy=Rustc=local' is used with pipelined compilation, rustc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions. (#17) * Add RUSTC_BOOTSTRAP guardrail for -Zno-codegen pipelining Injects RUSTC_BOOTSTRAP=1 + -Zallow-features= (empty list) on the metadata and full compile actions when pipelined_compilation is enabled on a stable/beta toolchain. The bootstrap env is required for -Zno-codegen on non-nightly rustc and must match across both actions for SVH compatibility. The empty allow-features list prevents the bootstrap env from silently unlocking #![feature(...)] in user code. Nightly toolchains skip both injections: unstable features are already allowed, and the guardrail would break legitimate #![feature(...)] usage. Escape hatch: if the user sets RUSTC_BOOTSTRAP in rustc_env / shell env or passes -Zallow-features=... via rustc_flags / extra_rustc_flag, rules_rust treats their configuration as authoritative and skips both injections. Tests: - //test/pipelining_bootstrap_gate: manual target that #![feature(trait_alias)] to validate E0725 fires on stable under the guardrail. - //test/unit/pipelined_compilation: guardrail_{baseline,user_env,user_flag, space_form,global_env,global_flag}_optout_test variants.
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When used with local compilation strategies that disable sandboxing, rustc's -Ldependency scan can pick up the _meta.rlib alongside the full '.rlbi', producing undefined-symbol link errors. To avoid this, emit the hollow metadata rlibs into a '_meta/' subdirectory, and add an explicit link to that directory for any metadata-consuming actions.