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This commit is contained in:
Esteban Küber 2019-09-19 14:52:38 -07:00
parent d64c90d40b
commit c34d9e6a92
1 changed files with 8 additions and 0 deletions
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8
src/librustc_typeck/check/mod.rs
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@ -3372,6 +3372,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
vec![self.tcx.types.err; len]
}
/// Given a vec of evaluated `FullfillmentError`s and an `fn` call argument expressions, we
/// walk the resolved types for each argument to see if any of the `FullfillmentError`s
/// reference a type argument. If they do, and there's only *one* argument that does, we point
/// at the corresponding argument's expression span instead of the `fn` call path span.
fn point_at_arg_instead_of_call_if_possible(
&self,
errors: &mut Vec<traits::FulfillmentError<'_>>,
@ -3384,9 +3388,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// the `?` operator.
for error in errors {
if let ty::Predicate::Trait(predicate) = error.obligation.predicate {
// Collect the argument position for all arguments that could have caused this
// `FullfillmentError`.
let mut referenced_in = final_arg_types.iter()
.flat_map(|(i, ty)| {
let ty = self.resolve_vars_if_possible(ty);
// We walk the argument type because the argument's type could have
// been `Option<T>`, but the `FullfillmentError` references `T`.
ty.walk()
.filter(|&ty| ty == predicate.skip_binder().self_ty())
.map(move |_| *i)