constify Iterator, take IV
#151281
constify Iterator, take IV
#151281
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Some changes occurred in compiler/rustc_hir/src/attrs cc @jdonszelmann, @JonathanBrouwer Some changes occurred to the CTFE machinery Some changes occurred in compiler/rustc_passes/src/check_attr.rs cc @jdonszelmann, @JonathanBrouwer Some changes occurred in compiler/rustc_attr_parsing |
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| /// ``` | ||
| #[inline] | ||
| #[unstable(feature = "iter_next_chunk", issue = "98326")] | ||
| #[rustc_non_const_trait_method] |
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Please also update the dev-guide docs to explain the attribute.
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| trace!("attempting to call a trait method"); | ||
| let trait_is_const = tcx.is_const_trait(trait_did); | ||
| let is_const = tcx.constness(callee) == hir::Constness::Const; |
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The code looks odd in combination with the comment just above it. The comment says "we can't look at the callee" and then the code proceeds to look at the callee...
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Can't determine the actual callee means we're calling Trait::func instead of <T as Trait>::func, here we're just looking at the constness of the trait method, although maybe I can adjust the comment above
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☔ The latest upstream changes (presumably #151291) made this pull request unmergeable. Please resolve the merge conflicts. |
| rustc_non_const_trait_method, AttributeType::Normal, template!(Word), | ||
| ErrorFollowing, EncodeCrossCrate::No, | ||
| "`#[rustc_non_const_trait_method]` should only used by the standard library to mark trait methods \ | ||
| as non-const to allow large traits to easier transition to const" |
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"traits an easier transition" or "traits to transition more easily"
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Like its predecessors (#92433, #102225, #106541), this PR allows one to make
Iteratorimplementationsconst, and thus enables the ability to haveforloops inconstcontexts. I've also included constifyingOption as IntoIterator,option::IntoIter as Iteratoras a minimal dogfooding example.But unlike its predecessors, it uses a new attribute (not unsound anymore!) that prevents any
Iteratorextension methods from being called. This is intentionally made minimal for an initial approval, the fun stuff like.fold,Range as Iteratorcould be done later.cc @rust-lang/wg-const-eval, cc @oli-obk to review the compiler parts
cc #92476