bjoernager/rust
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Don't point at another arg if we're already pointing at one

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This commit is contained in:
Michael Goulet 2022-06-28 19:32:12 -07:00
parent 75337775f7
commit 23f3b0dfd0
5 changed files with 78 additions and 19 deletions
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38
compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
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@ -1629,7 +1629,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
return;
}
for error in errors {
'outer: for error in errors {
// Only if the cause is somewhere inside the expression we want try to point at arg.
// Otherwise, it means that the cause is somewhere else and we should not change
// anything because we can break the correct span.
@ -1671,10 +1671,32 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
_ => continue,
};
let self_ = self.resolve_vars_if_possible(self_);
let ty_matches_self = |ty: Ty<'tcx>| ty.walk().any(|arg| arg == self_);
let typeck_results = self.typeck_results.borrow();
for (idx, arg) in args.iter().enumerate() {
// Don't adjust the span if we already have a more precise span
// within one of the args.
if arg.span.contains(error.obligation.cause.span) {
let references_arg =
typeck_results.expr_ty_opt(arg).map_or(false, &ty_matches_self)
|| expected_tys.get(idx).copied().map_or(false, &ty_matches_self);
if references_arg && !arg.span.from_expansion() {
error.obligation.cause.map_code(|parent_code| {
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: args[idx].hir_id,
call_hir_id: expr.hir_id,
parent_code,
}
})
}
continue 'outer;
}
}
// Collect the argument position for all arguments that could have caused this
// `FulfillmentError`.
let typeck_results = self.typeck_results.borrow();
let mut referenced_in: Vec<_> = std::iter::zip(expected_tys, args)
.enumerate()
.flat_map(|(idx, (expected_ty, arg))| {
@ -1688,7 +1710,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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 `FulfillmentError` references `T`.
if ty.walk().any(|arg| arg == self_) { Some(i) } else { None }
if ty_matches_self(ty) { Some(i) } else { None }
})
.collect();
@ -1699,18 +1721,18 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
referenced_in.sort_unstable();
referenced_in.dedup();
if let (Some(ref_in), None) = (referenced_in.pop(), referenced_in.pop()) {
if let &[idx] = &referenced_in[..] {
// Do not point at the inside of a macro.
// That would often result in poor error messages.
if args[ref_in].span.from_expansion() {
return;
if args[idx].span.from_expansion() {
continue;
}
// We make sure that only *one* argument matches the obligation failure
// and we assign the obligation's span to its expression's.
error.obligation.cause.span = args[ref_in].span;
error.obligation.cause.span = args[idx].span;
error.obligation.cause.map_code(|parent_code| {
ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id: args[ref_in].hir_id,
arg_hir_id: args[idx].hir_id,
call_hir_id: expr.hir_id,
parent_code,
}