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Only emit one error per unsized binding, instead of one per usage #113183

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merged 4 commits into from
Oct 27, 2023
Merged

Only emit one error per unsized binding, instead of one per usage #113183

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3d86b8a
Add test for #56607
estebank Jun 30, 2023
2f79681
Only emit one error per unsized binding, instead of one per usage
estebank Jun 30, 2023
124d6d8
Remove need for `has_errors()` check
estebank Oct 9, 2023
568b316
Move predicate error early check to its own method
estebank Oct 9, 2023
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45 changes: 39 additions & 6 deletions compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 104,8 @@ pub trait TypeErrCtxtExt<'tcx> {
error: &SelectionError<'tcx>,
);

fn fn_arg_obligation(&self, obligation: &PredicateObligation<'tcx>) -> bool;

fn report_const_param_not_wf(
&self,
ty: Ty<'tcx>,
Expand Down Expand Up @@ -163,12 165,6 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
predicate: error.obligation.predicate,
index: Some(index),
});

self.reported_trait_errors
.borrow_mut()
.entry(span)
.or_default()
.push(error.obligation.predicate);
}

// We do this in 2 passes because we want to display errors in order, though
Expand Down Expand Up @@ -206,6 202,18 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
for (error, suppressed) in iter::zip(&errors, &is_suppressed) {
if !suppressed && error.obligation.cause.span.from_expansion() == from_expansion {
self.report_fulfillment_error(error);
// We want to ignore desugarings here: spans are equivalent even
// if one is the result of a desugaring and the other is not.
let mut span = error.obligation.cause.span;
let expn_data = span.ctxt().outer_expn_data();
if let ExpnKind::Desugaring(_) = expn_data.kind {
span = expn_data.call_site;
}
self.reported_trait_errors
.borrow_mut()
.entry(span)
.or_default()
.push(error.obligation.predicate);
}
}
}
Expand Down Expand Up @@ -428,6 436,11 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
{
return;
}
if self.fn_arg_obligation(&obligation) {
// Silence redundant errors on binding acccess that are already
// reported on the binding definition (#56607).
return;
}
let trait_ref = trait_predicate.to_poly_trait_ref();

let (post_message, pre_message, type_def) = self
Expand Down Expand Up @@ -924,6 937,26 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
err.emit();
}

fn fn_arg_obligation(&self, obligation: &PredicateObligation<'tcx>) -> bool {
if let ObligationCauseCode::FunctionArgumentObligation {
arg_hir_id,
..
} = obligation.cause.code()
&& let Some(Node::Expr(arg)) = self.tcx.hir().find(*arg_hir_id)
&& let arg = arg.peel_borrows()
&& let hir::ExprKind::Path(hir::QPath::Resolved(
None,
hir::Path { res: hir::def::Res::Local(hir_id), .. },
)) = arg.kind
&& let Some(Node::Pat(pat)) = self.tcx.hir().find(*hir_id)
&& let Some(preds) = self.reported_trait_errors.borrow().get(&pat.span)
&& preds.contains(&obligation.predicate)
{
return true;
}
false
}

fn report_const_param_not_wf(
&self,
ty: Ty<'tcx>,
Expand Down
5 changes: 5 additions & 0 deletions tests/ui/sized/unsized-binding.rs
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Original file line number Diff line number Diff line change
@@ -0,0 1,5 @@
fn main() {
let x = *""; //~ ERROR E0277
println!("{}", x);
println!("{}", x);
}
13 changes: 13 additions & 0 deletions tests/ui/sized/unsized-binding.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 1,13 @@
error[E0277]: the size for values of type `str` cannot be known at compilation time
--> $DIR/unsized-binding.rs:2:9
|
LL | let x = *"";
| ^ doesn't have a size known at compile-time
|
= help: the trait `Sized` is not implemented for `str`
= note: all local variables must have a statically known size
= help: unsized locals are gated as an unstable feature

error: aborting due to previous error

For more information about this error, try `rustc --explain E0277`.
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