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const-in-pattern: test that the PartialEq impl does not need to be const

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This commit is contained in:
Ralf Jung 2025-01-03 10:55:15 +01:00
parent c528b8c678
commit b806dccdc4
2 changed files with 58 additions and 0 deletions
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4
compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs
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@ -491,6 +491,10 @@ fn type_has_partial_eq_impl<'tcx>(
// `PartialEq` for some lifetime but *not* for `'static`? If this ever becomes a problem
// we'll need to leave some sort of trace of this requirement in the MIR so that borrowck
// can ensure that the type really implements `PartialEq`.
// We also do *not* require `const PartialEq`, not even in `const fn`. This violates the model
// that patterns can only do things that the code could also do without patterns, but it is
// needed for backwards compatibility. The actual pattern matching compares primitive values,
// `PartialEq::eq` never gets invoked, so there's no risk of us running non-const code.
(
infcx.predicate_must_hold_modulo_regions(&partial_eq_obligation),
automatically_derived,