bjoernager/rust
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Move const trait bounds checks to MIR constck

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Fixes #109543. When checking paths in HIR typeck, we don't want to check
for const predicates since all we want might just be a function pointer.
Therefore we move this to MIR constck and check that bounds are met
during MIR constck.
This commit is contained in:
Deadbeef 2023-03-24 09:17:51 +00:00
parent cbc064b341
commit b17e6680d6
27 changed files with 438 additions and 323 deletions
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51
compiler/rustc_const_eval/src/transform/check_consts/check.rs
View file

@ -722,6 +722,32 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
}
};
// Check that all trait bounds that are marked as `~const` can be satisfied.
//
// Typeck only does a "non-const" check since it operates on HIR and cannot distinguish
// which path expressions are getting called on and which path expressions are only used
// as function pointers. This is required for correctness.
let infcx = tcx.infer_ctxt().build();
let ocx = ObligationCtxt::new(&infcx);
let predicates = tcx.predicates_of(callee).instantiate(tcx, substs);
let cause = ObligationCause::new(
terminator.source_info.span,
self.body.source.def_id().expect_local(),
ObligationCauseCode::ItemObligation(callee),
);
let normalized_predicates = ocx.normalize(&cause, param_env, predicates);
ocx.register_obligations(traits::predicates_for_generics(
|_, _| cause.clone(),
self.param_env,
normalized_predicates,
));
let errors = ocx.select_all_or_error();
if !errors.is_empty() {
infcx.err_ctxt().report_fulfillment_errors(&errors);
}
// Attempting to call a trait method?
if let Some(trait_id) = tcx.trait_of_item(callee) {
trace!("attempting to call a trait method");
@ -749,31 +775,6 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
selcx.select(&obligation)
};
// do a well-formedness check on the trait method being called. This is because typeck only does a
// "non-const" check. This is required for correctness here.
{
let infcx = tcx.infer_ctxt().build();
let ocx = ObligationCtxt::new(&infcx);
let predicates = tcx.predicates_of(callee).instantiate(tcx, substs);
let cause = ObligationCause::new(
terminator.source_info.span,
self.body.source.def_id().expect_local(),
ObligationCauseCode::ItemObligation(callee),
);
let normalized_predicates = ocx.normalize(&cause, param_env, predicates);
ocx.register_obligations(traits::predicates_for_generics(
|_, _| cause.clone(),
self.param_env,
normalized_predicates,
));
let errors = ocx.select_all_or_error();
if !errors.is_empty() {
infcx.err_ctxt().report_fulfillment_errors(&errors);
}
}
match implsrc {
Ok(Some(ImplSource::Param(_, ty::BoundConstness::ConstIfConst))) => {
debug!(