bjoernager/rust
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Don't pick T: FnPtr nested goals

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This commit is contained in:
Boxy 2025-01-22 06:40:43 +00:00
parent c234b839d1
commit 3ef506fb4d
26 changed files with 389 additions and 69 deletions
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23
compiler/rustc_trait_selection/src/solve/fulfill.rs
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@ -513,8 +513,27 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
_ => ChildMode::PassThrough,
};
let nested_goals = candidate.instantiate_nested_goals(self.span());
// If the candidate requires some `T: FnPtr` bound which does not hold should not be treated as
// an actual candidate, instead we should treat them as if the impl was never considered to
// have potentially applied. As if `impl<A, R> Trait for for<..> fn(..A) -> R` was written
// instead of `impl<T: FnPtr> Trait for T`.
//
// We do this as a separate loop so that we do not choose to tell the user about some nested
// goal before we encounter a `T: FnPtr` nested goal.
for nested_goal in &nested_goals {
if let Some(fn_ptr_trait) = tcx.lang_items().fn_ptr_trait()
&& let Some(poly_trait_pred) = nested_goal.goal().predicate.as_trait_clause()
&& poly_trait_pred.def_id() == fn_ptr_trait
&& let Err(NoSolution) = nested_goal.result()
{
return ControlFlow::Break(self.obligation.clone());
}
}
let mut impl_where_bound_count = 0;
for nested_goal in candidate.instantiate_nested_goals(self.span()) {
for nested_goal in nested_goals {
trace!(nested_goal = ?(nested_goal.goal(), nested_goal.source(), nested_goal.result()));
let make_obligation = |cause| Obligation {
@ -605,7 +624,7 @@ impl<'tcx> ProofTreeVisitor<'tcx> for BestObligation<'tcx> {
}
}
#[derive(Copy, Clone)]
#[derive(Debug, Copy, Clone)]
enum ChildMode<'tcx> {
// Try to derive an `ObligationCause::{ImplDerived,BuiltinDerived}`,
// and skip all `GoalSource::Misc`, which represent useless obligations