rustc_resolve: don't deny outer type parameters in embedded constants. #41939
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The resolve part looks good. |
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☔ The latest upstream changes (presumably #41965) made this pull request unmergeable. Please resolve the merge conflicts. |
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…petrochenkov rustc_resolve: don't deny outer type parameters in embedded constants. This solves a problem noted at rust-lang#29646 (comment), where an associated const default in a trait couldn't refer to `Self` or type parameters, due to inaccuracies in lexical scoping. I've also allowed "embedded expressions" (`[T; expr]`, `[x; expr]`, `typeof expr`) to refer to type parameters in scope. *However*, the typesystem still doesn't handle rust-lang#34344. Fully resolving that issue requires breaking cycles more aggressively (e.g. lazy evaluation), *even* in when the expression doesn't depend on type parameters, to type-check it at all, and then also type-level "constant projections" (in the vein of `{expr}` from const generics).
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…petrochenkov rustc_resolve: don't deny outer type parameters in embedded constants. This solves a problem noted at rust-lang#29646 (comment), where an associated const default in a trait couldn't refer to `Self` or type parameters, due to inaccuracies in lexical scoping. I've also allowed "embedded expressions" (`[T; expr]`, `[x; expr]`, `typeof expr`) to refer to type parameters in scope. *However*, the typesystem still doesn't handle rust-lang#34344. Fully resolving that issue requires breaking cycles more aggressively (e.g. lazy evaluation), *even* in when the expression doesn't depend on type parameters, to type-check it at all, and then also type-level "constant projections" (in the vein of `{expr}` from const generics).
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This solves a problem noted at #29646 (comment), where an associated const default in a trait couldn't refer to
Selfor type parameters, due to inaccuracies in lexical scoping.I've also allowed "embedded expressions" (
[T; expr],[x; expr],typeof expr) to refer to type parameters in scope. However, the typesystem still doesn't handle #34344.Fully resolving that issue requires breaking cycles more aggressively (e.g. lazy evaluation), even in when the expression doesn't depend on type parameters, to type-check it at all, and then also type-level "constant projections" (in the vein of
{expr}from const generics).