Don't give APITs names with macro expansion placeholder fragments in it #142393
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r? @davidtwco rustbot has assigned @davidtwco. Use |
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This PR changes a file inside |
compiler-errors
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Jun 12, 2025
| LL | let () = x; | ||
| | ^^ - this expression has type `impl Foo<bar!()>` | ||
| | | | ||
| | expected type parameter `impl Foo<bar!()>`, found `()` |
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For contrast, this used to render like impl Foo<!()>, where !() is the placeholder fragment.
davidtwco
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Jun 12, 2025
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r=me if @petrochenkov is happy since he's also assigned |
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The
DefCollectorpreviously calledpprust::ty_to_stringto construct a name for APITs (arg-position impl traits). Theast::Tythat was being formatted however has already had its macro calls replaced with "placeholder fragments", which end up rendering like!()(or ICEing, in the case of #140333, since it led to a placeholder struct field with no name).Instead, collect the name of the APIT before we visit its macros and replace them with placeholders in the macro expander. This makes the implementation a bit more involved, but AFAICT there's no better way to do this since we can't do a reverse mapping from placeholder fragment -> original macro call AST.
Fixes #140333