Assemble const bounds via normal item bounds in old solver too #143235
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| trait Baz: const Bar {} | ||
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| trait Foo { | ||
| // Well-formedenss of `Baz` requires `<Self as Foo>::Bar: const Bar`. |
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| // Well-formedenss of `Baz` requires `<Self as Foo>::Bar: const Bar`. | |
| // Well-formedness of `Baz` requires `<Self as Foo>::Bar: const Bar`. |
davidtwco
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Jul 1, 2025
| } | ||
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| let is_match = | ||
| infcx.probe(|_| match_candidate(selcx, obligation, data, true, |_, _| {}).is_ok()); |
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| infcx.probe(|_| match_candidate(selcx, obligation, data, true, |_, _| {}).is_ok()); | |
| infcx.probe(|_| match_candidate(selcx, obligation, data, false, |_, _| {}).is_ok()); |
In trying to use this patch locally with my experimental const sizedness changes, I find that I get errors in libcore when this does normalisation.
I don't have a minimal example unfortunately, but the issue was when:
obligation.predicate.trait_refis<<char as str::pattern::Pattern>::Searcher<'_> as marker::MetaSized>data.trait_refwas<<char as str::pattern::Pattern>::Searcher<'_> as marker::MetaSized>- ..then normalised to
<str::pattern::CharSearcher<'_> as marker::MetaSized>
- ..then normalised to
- ..and then
is_matchends up beingfalse
I don't know that it's the correct solution but changing this to false allows the crate to compile successfully.
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Hm, that change is not right in general and would cause additional failures later on since predicates that we get from the item bounds need to be normalized after substitution.
I think you should identify where the error was being emitted, what phase/step of checking we're doing, the param-env, why the goal predicate is not being normalized, etc, since it doesn't have much to do with this PR I think.
oli-obk
reviewed
Jul 1, 2025
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| let mut consider_ty = obligation.predicate.self_ty(); | ||
| while let ty::Alias(kind @ (ty::Projection | ty::Opaque), alias_ty) = *consider_ty.kind() { | ||
| for clause in tcx.item_bounds(alias_ty.def_id).iter_instantiated(tcx, alias_ty.args) { |
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why can't this use the is_conditionally_const "fast path"?
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Because the constness of these item bounds is not dependent on the constness of the associated item. If I have:
trait Foo {
type Assoc: const A + ~const B;
}
<T as Foo>::Assoc is always const A, but only const B if T: const Foo.
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Rollup of 11 pull requests Successful merges: - #131923 (Derive `Copy` and `Hash` for `IntErrorKind`) - #138340 (Remove some unsized tuple impls now that we don't support unsizing tuples anymore) - #141219 (Change `{Box,Arc,Rc,Weak}::into_raw` to only work with `A = Global`) - #142212 (bootstrap: validate `rust.codegen-backends` & `target.<triple>.codegen-backends`) - #142237 (Detect more cases of unused_parens around types) - #142964 (Attribute rework: a parser for single attributes without arguments) - #143070 (Rewrite `macro_rules!` parser to not use the MBE engine itself) - #143235 (Assemble const bounds via normal item bounds in old solver too) - #143261 (Feed `explicit_predicates_of` instead of `predicates_of`) - #143276 (loop match: handle opaque patterns) - #143306 (Add `track_caller` attributes to trace origin of Clippy lints) r? `@ghost` `@rustbot` modify labels: rollup try-job: aarch64-apple try-job: x86_64-msvc-1 try-job: x86_64-gnu try-job: dist-i586-gnu-i586-i686-musl try-job: test-various
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Rollup of 11 pull requests Successful merges: - #131923 (Derive `Copy` and `Hash` for `IntErrorKind`) - #138340 (Remove some unsized tuple impls now that we don't support unsizing tuples anymore) - #141219 (Change `{Box,Arc,Rc,Weak}::into_raw` to only work with `A = Global`) - #142212 (bootstrap: validate `rust.codegen-backends` & `target.<triple>.codegen-backends`) - #142237 (Detect more cases of unused_parens around types) - #142964 (Attribute rework: a parser for single attributes without arguments) - #143070 (Rewrite `macro_rules!` parser to not use the MBE engine itself) - #143235 (Assemble const bounds via normal item bounds in old solver too) - #143261 (Feed `explicit_predicates_of` instead of `predicates_of`) - #143276 (loop match: handle opaque patterns) - #143306 (Add `track_caller` attributes to trace origin of Clippy lints) r? `@ghost` `@rustbot` modify labels: rollup try-job: aarch64-apple try-job: x86_64-msvc-1 try-job: x86_64-gnu try-job: dist-i586-gnu-i586-i686-musl try-job: test-various
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Rollup merge of #143235 - compiler-errors:const-item-bound, r=oli-obk Assemble const bounds via normal item bounds in old solver too Fixes the first example in https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/elaboration.20of.20const.20bounds.3F/with/526378135 The code duplication here is not that nice, but it's at least very localized. cc `@davidtwco` r? oli-obk
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Fixes the first example in https://rust-lang.zulipchat.com/#narrow/channel/144729-t-types/topic/elaboration.20of.20const.20bounds.3F/with/526378135
The code duplication here is not that nice, but it's at least very localized.
cc @davidtwco
r? oli-obk