stepping into impls for normalization is unproductive #139900
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rustbot
added
S-waiting-on-review
lcnr
force-pushed
the
normalizes-to-where-bounds-unproductive
branch
from
bb2b757 to
48e119e
Compare
compiler-errors
approved these changes
Apr 16, 2025
|
@bors r+ rollup |
bors
added
S-waiting-on-bors
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Apr 17, 2025
…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
rust-timer
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Apr 17, 2025
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`
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
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