Add test for bad cast with deferred projection equality #108287
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…t, r=spastorino Add test for bad cast with deferred projection equality 1. Unification during coercion (`Coerce::unify`) needs to consider deferred projection obligations (at least pass over them with `predicate_may_hold` or something, to disqualify any totally wrong unifications) -- otherwise, we'll shallowly consider `<u8 as Add>::Output` and `char` as coercible during `FnCtxt::try_coerce`, which will fail later when the nested obligations are registered and processed. 2. Cast checking needs to be able to structurally normalize types so it sees `u8` instead of `<u8 as Add>::Output`. Otherwise it'll always consider the latter as part of a non-primitive cast. Currently `FnCtxt::normalize` doesn't do anything useful here, interestingly. I tried looking into both of these and it's not immediately clear where to refactor existing typeck code to fix this (at least the latter), but I'm gonna commit a test for it at least so we don't forget. This is one of the issues that's keeping us from building larger projects.
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Rollup of 10 pull requests Successful merges: - rust-lang#106541 (implement const iterator using `rustc_do_not_const_check`) - rust-lang#106918 (Rebuild BinaryHeap on unwind from retain) - rust-lang#106923 (Restore behavior when primary bundle is missing) - rust-lang#108169 (Make query keys `Copy`) - rust-lang#108287 (Add test for bad cast with deferred projection equality) - rust-lang#108370 (std: time: Avoid to use "was created" in elapsed() description) - rust-lang#108377 (Fix ICE in 'duplicate diagnostic item' diagnostic) - rust-lang#108388 (parser: provide better suggestions and errors on closures with braces missing) - rust-lang#108391 (Fix `is_terminal`'s handling of long paths on Windows.) - rust-lang#108401 (diagnostics: remove inconsistent English article "this" from E0107) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup
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Unification during coercion (
Coerce::unify) needs to consider deferred projection obligations (at least pass over them withpredicate_may_holdor something, to disqualify any totally wrong unifications) -- otherwise, we'll shallowly consider<u8 as Add>::Outputandcharas coercible duringFnCtxt::try_coerce, which will fail later when the nested obligations are registered and processed.Cast checking needs to be able to structurally normalize types so it sees
u8instead of<u8 as Add>::Output. Otherwise it'll always consider the latter as part of a non-primitive cast. CurrentlyFnCtxt::normalizedoesn't do anything useful here, interestingly.I tried looking into both of these and it's not immediately clear where to refactor existing typeck code to fix this (at least the latter), but I'm gonna commit a test for it at least so we don't forget. This is one of the issues that's keeping us from building larger projects.