Avoid loading needless proc-macro dependencies #38024
5 participants
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cc @nrc |
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Could this be reviewed and prioritised? This is blocking rustup in Servo. |
| @@ -67,6 +67,8 @@ pub struct CrateSource { | ||
| #[derive(RustcEncodable, RustcDecodable, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Debug)] | ||
| pub enum DepKind { | ||
| + /// A dependency that is only used for its macros, none of which are visible from other crates. | ||
| + UnexportedMacrosOnly, |
Are these only used by monomorphised functions or is there some reason to include them. Would be good to comment in any case.
UnexportedMacrosOnly are only included in the metadata as placeholders (the CrateNum of a dependency is computed from its position in the dependency list) -- I'll add a comment.
Does that answer your question? (not sure how monomorphised functions are relevant)
Oh, I see -- monomorphised functions from extern crates might need to access non-visible functions. I don't think this is relevant to macros though, since expansion finishes before monomorphization.
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@bors r=nrc |
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@bors p=1 |
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Fixes #37958 when no proc-macros are exported; in particular, without
pub extern crate proc_macros;,#![feature(macro_reexport)], or#![feature(use_extern_macros)].I opened rust-lang/cargo#3334 for exported proc macros.
r? @alexcrichton