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Fix error message with non-tupled bare fn trait

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This commit is contained in:
Michael Goulet 2022-07-30 09:41:19 +00:00
parent 40336865fe
commit 8b64988575
10 changed files with 101 additions and 38 deletions
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30
compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
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@ -22,6 +22,7 @@ use rustc_hir::intravisit::Visitor;
use rustc_hir::GenericParam;
use rustc_hir::Item;
use rustc_hir::Node;
use rustc_infer::infer::TypeTrace;
use rustc_infer::traits::TraitEngine;
use rustc_middle::traits::select::OverflowError;
use rustc_middle::ty::abstract_const::NotConstEvaluatable;
@ -941,9 +942,14 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
self.reported_closure_mismatch.borrow_mut().insert((span, found_span));
let mut not_tupled = false;
let found = match found_trait_ref.skip_binder().substs.type_at(1).kind() {
ty::Tuple(ref tys) => vec![ArgKind::empty(); tys.len()],
_ => vec![ArgKind::empty()],
_ => {
not_tupled = true;
vec![ArgKind::empty()]
}
};
let expected_ty = expected_trait_ref.skip_binder().substs.type_at(1);
@ -951,10 +957,28 @@ impl<'a, 'tcx> InferCtxtExt<'tcx> for InferCtxt<'a, 'tcx> {
ty::Tuple(ref tys) => {
tys.iter().map(|t| ArgKind::from_expected_ty(t, Some(span))).collect()
}
_ => vec![ArgKind::Arg("_".to_owned(), expected_ty.to_string())],
_ => {
not_tupled = true;
vec![ArgKind::Arg("_".to_owned(), expected_ty.to_string())]
}
};
if found.len() == expected.len() {
// If this is a `Fn` family trait and either the expected or found
// is not tupled, then fall back to just a regular mismatch error.
// This shouldn't be common unless manually implementing one of the
// traits manually, but don't make it more confusing when it does
// happen.
if Some(expected_trait_ref.def_id()) != tcx.lang_items().gen_trait() && not_tupled {
self.report_and_explain_type_error(
TypeTrace::poly_trait_refs(
&obligation.cause,
true,
expected_trait_ref,
found_trait_ref,
),
ty::error::TypeError::Mismatch,
)
} else if found.len() == expected.len() {
self.report_closure_arg_mismatch(
span,
found_span,