43babed7e2
Fix regionck failure when converting Index to IndexMut Fixes #74933 Consider an overloaded index expression `base[index]`. Without knowing whether it will be mutated, this will initially be desugared into `<U as Index<T>>::index(&base, index)` for some `U` and `T`. Let `V` be the `expr_ty_adjusted` of `index`. If this expression ends up being used in any mutable context (or used in a function call with `&mut self` receiver before #72280), we will need to fix it up. The current code will rewrite it to `<U as IndexMut<V>>::index_mut(&mut base, index)`. In most cases this is fine as `V` will be equal to `T`, however this is not always true when `V/T` are references, as they may have different region. This issue is quite subtle before #72280 as this code path is only used to fixup function receivers, but after #72280 we've made this a common path. The solution is basically just rewrite it to `<U as IndexMut<T>>::index_mut(&mut base, index)`. `T` can retrieved in the fixup path using `node_substs`. |
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| COMPILER_TESTS.md | ||