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Auto merge of #100982 - fee1-dead-contrib:const-impl-requires-const-trait, r=oli-obk

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Require `#[const_trait]` on `Trait` for `impl const Trait`

r? `@oli-obk`
This commit is contained in:
bors 2022-09-22 04:22:24 +00:00
commit 7a8636c843
80 changed files with 433 additions and 245 deletions
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44
compiler/rustc_const_eval/src/transform/check_consts/check.rs
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@ -13,8 +13,11 @@ use rustc_middle::ty::{self, adjustment::PointerCast, Instance, InstanceDef, Ty,
use rustc_middle::ty::{Binder, TraitPredicate, TraitRef, TypeVisitable};
use rustc_mir_dataflow::{self, Analysis};
use rustc_span::{sym, Span, Symbol};
use rustc_trait_selection::traits::error_reporting::InferCtxtExt;
use rustc_trait_selection::traits::SelectionContext;
use rustc_trait_selection::infer::InferCtxtExt;
use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
use rustc_trait_selection::traits::{
self, ObligationCauseCode, SelectionContext, TraitEngine, TraitEngineExt,
};
use std::mem;
use std::ops::Deref;
@ -739,6 +742,43 @@ 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.
tcx.infer_ctxt().enter(|infcx| {
let mut fulfill_cx = <dyn TraitEngine<'_>>::new(infcx.tcx);
let predicates = tcx.predicates_of(callee).instantiate(tcx, substs);
let hir_id = tcx
.hir()
.local_def_id_to_hir_id(self.body.source.def_id().expect_local());
let cause = || {
ObligationCause::new(
terminator.source_info.span,
hir_id,
ObligationCauseCode::ItemObligation(callee),
)
};
let normalized = infcx.partially_normalize_associated_types_in(
cause(),
param_env,
predicates,
);
for p in normalized.obligations {
fulfill_cx.register_predicate_obligation(&infcx, p);
}
for obligation in traits::predicates_for_generics(
|_, _| cause(),
self.param_env,
normalized.value,
) {
fulfill_cx.register_predicate_obligation(&infcx, obligation);
}
let errors = fulfill_cx.select_all_or_error(&infcx);
if !errors.is_empty() {
infcx.report_fulfillment_errors(&errors, None, false);
}
});
match implsrc {
Ok(Some(ImplSource::Param(_, ty::BoundConstness::ConstIfConst))) => {
debug!(