Add environment variable query #130883
Add environment variable query #130883
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| @@ -336,6 +337,20 @@ fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) { | |||
| ) | |||
| } | |||
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| fn env_var(tcx: TyCtxt<'_>, key: Symbol) -> Option<Symbol> { | |||
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I was unsure where to put the query definition, so I just put it in the same file as some other general queries.
| @@ -336,6 +337,20 @@ fn early_lint_checks(tcx: TyCtxt<'_>, (): ()) { | |||
| ) | |||
| } | |||
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| fn env_var(tcx: TyCtxt<'_>, key: Symbol) -> Option<Symbol> { | |||
| let var = match std::env::var(key.as_str()) { | |||
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Is there something similar to Clippy's disallowed-methods that I could use to lint against usage of std::env::var in the compiler, and direct users towards the query instead?
See also rust-lang/cargo#11588.
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There's some rustc-internal lints in https://github.com/rust-lang/rust/blob/master/compiler/rustc_lint/src/internal.rs
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| // Also add the variable to Cargo's dependency tracking | ||
| tcx.sess.psess.env_depinfo.borrow_mut().insert((key, var)); |
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Hmm, a complication here is that this query will only work with the dependency info files that Cargo reads if it's called before passes::write_dep_info at:
rust/compiler/rustc_driver_impl/src/lib.rs
Line 437 in a3f76a2
So everything done during passes::analysis and Linker::codegen_and_build_linker will need some other mechanism for populating ParseSess::env_depinfo.
Is it possible for us to move the write_dep_info pass to the very end, or just before linking? Or is it important that it happens as soon as possible for parallelizing Cargo, or something?
Generally,
rustcprefers command-line arguments, but in some cases, an environment variable really is the most sensible option. We should make sure that this works properly with the compiler's change-tracking mechanisms, such that changing the relevant environment variable causes a rebuild.This PR is a first step forwards in doing that.
Part of the work needed to do #118204, see #129342 for some discussion.
r? @petrochenkov