rust/compiler/rustc_middle
Guillaume Gomez d2aef58eb5
Rollup merge of #108203 - compiler-errors:rpitit-fix-defaults-2, r=jackh726
Fix RPITITs in default trait methods (by assuming projection predicates in param-env)

Instead of having special projection logic that allows us to turn `ProjectionTy(RPITIT, [Self#0, ...])` into `OpaqueTy(RPITIT, [Self#0, ...])`, we can instead augment the param-env of default trait method bodies to assume these as projection predicates. This should allow us to only project where we're allowed to!

In order to make this work without introducing a bunch of cycle errors, we additionally tweak the `OpaqueTypeExpander` used by `ParamEnv::with_reveal_all_normalized` to not normalize the right-hand side of projection predicates. This should be fine, because if we use the projection predicate to normalize some other projection type, we'll continue to normalize the opaque that it gets projected to.

This also makes it possible to support default trait methods with RPITITs in an associated-type based RPITIT lowering strategy without too much extra effort.

Fixes #107002
Alternative to #108142
2023-02-19 14:47:56 +01:00
..
src Rollup merge of #108203 - compiler-errors:rpitit-fix-defaults-2, r=jackh726 2023-02-19 14:47:56 +01:00
Cargo.toml Give a more helpful error for "trimmed_def_paths construted" 2022-12-22 13:12:15 -06:00
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