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Return correct HirId when finding body owner in diagnostics Fixes #129145 Fixes #128810 r? ```@compiler-errors``` ```rust fn generic<const N: u32>() {} trait Collate<const A: u32> { type Pass; fn collate(self) -> Self::Pass; } impl<const B: u32> Collate<B> for i32 { type Pass = (); fn collate(self) -> Self::Pass { generic::<{ true }>() //~^ ERROR: mismatched types } } ``` When type checking the `{ true }` anon const we would error with a type mismatch. This then results in diagnostics code attempting to check whether its due to a type mismatch with the return type. That logic was implemented by walking up the hir until we reached the body owner, except instead of using the `enclosing_body_owner` function it special cased various hir nodes incorrectly resulting in us walking out of the anon const and stopping at `fn collate` instead. This then resulted in diagnostics logic inside of the anon consts `ParamEnv` attempting to do trait solving involving the `<i32 as Collate<B>>::Pass` type which ICEs because it is in the wrong environment. I have rewritten this function to just walk up until it hits the `enclosing_body_owner` and made some other changes since I found this pretty hard to read/understand. Hopefully it's easier to understand now, it also makes it more obvious that this is not implemented in a very principled way and is definitely missing cases :)
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