stepping into impls for normalization is unproductive #139900
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…iaskrgr Rollup of 9 pull requests Successful merges: - rust-lang#135340 (Add `explicit_extern_abis` Feature and Enforce Explicit ABIs) - rust-lang#139440 (rustc_target: RISC-V: feature addition batch 2) - rust-lang#139667 (cfi: Remove #[no_sanitize(cfi)] for extern weak functions) - rust-lang#139828 (Don't require rigid alias's trait to hold) - rust-lang#139854 (Improve parse errors for stray lifetimes in type position) - rust-lang#139889 (Clean UI tests 3 of n) - rust-lang#139894 (Fix `opt-dist` CLI flag and make it work without LLD) - rust-lang#139900 (stepping into impls for normalization is unproductive) - rust-lang#139915 (replace some #[rustc_intrinsic] usage with use of the libcore declarations) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#139900 - lcnr:normalizes-to-where-bounds-unproductive, r=compiler-errors stepping into impls for normalization is unproductive See the inline comment. This builds on the reasoning from rust-lang#136824 (https://gist.github.com./lcnr/c49d887bbd34f5d05c36d1cf7a1bf5a5). Fixes rust-lang/trait-system-refactor-initiative#176. Looking at the end of the gist: > The only ways to project out of a constructor are the following: > - accessing an associated item, either its type or its item bounds > - accessing super predicates Detecting cases where we accessing the type of an associated item is easy, it's simply when we normalize. I don't yet know how to detect whether we step out of an impl by accessing item bounds. Once we also detect these cases we should be able to soundly support arbitrary coinductive traits. Luckily this does not matter for this PR :> r? `@compiler-errors` cc `@nikomatsakis`
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See the inline comment. This builds on the reasoning from #136824 (https://gist.github.com./lcnr/c49d887bbd34f5d05c36d1cf7a1bf5a5). Fixes rust-lang/trait-system-refactor-initiative#176.
Looking at the end of the gist:
Detecting cases where we accessing the type of an associated item is easy, it's simply when we normalize. I don't yet know how to detect whether we step out of an impl by accessing item bounds. Once we also detect these cases we should be able to soundly support arbitrary coinductive traits. Luckily this does not matter for this PR :>
r? @compiler-errors cc @nikomatsakis