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Fix marker trait winnowing depending on impl order #153847

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Fix marker trait winnowing depending on impl order #153847

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2 changes: 1 addition & 1 deletion compiler/rustc_trait_selection/src/traits/select/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -750,7 +750,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
if pred.0.has_free_regions()
|| pred.0.has_bound_regions()
|| pred.0.has_non_region_infer()
|| pred.0.has_non_region_infer()
|| pred.0.has_non_region_param()
{
Ok(EvaluatedToOkModuloRegions)
} else {
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15 changes: 8 additions & 7 deletions tests/ui/marker_trait_attr/overlapping-impl-1-modulo-regions.rs
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@oli-obk oli-obk Mar 14, 2026

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Since this mentions the old solver, is there an equivalent next solver test that this one was derived from?

Either way, should probably run on both solvers

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@traviscross traviscross Mar 14, 2026

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None that I could find. I added the directives to test with both solvers.

Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
//@ known-bug: #109481
//@ check-pass
//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
//
// While the `T: Copy` is always applicable when checking
// that the impl `impl<T: Copy> F for T {}` is well formed,
// the old trait solver can only approximate this by checking
// that there are no inference variables in the obligation and
// no region constraints in the evaluation result.
// Regression test for #109481 and #84917.
//
// Because of this we end up with ambiguity here.
// Overlapping marker trait impls where one has a `T: 'static` bound
// should be accepted. A bug previously made marker trait winnowing
// order-dependent, producing a spurious E0310 here.
#![feature(marker_trait_attr)]

#[marker]
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17 changes: 0 additions & 17 deletions tests/ui/marker_trait_attr/overlapping-impl-1-modulo-regions.stderr
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