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Reduce verbosity of error
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@estebank
estebank committed Oct 7, 2023
1 parent 53a0ae0 commit b09ff86
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Showing 3 changed files with 24 additions and 43 deletions.
37 changes: 21 additions & 16 deletions compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -110,7 +110,7 @@ pub trait TypeErrCtxtExt<'tcx> {
obligation: &PredicateObligation<'tcx>,
trait_ref: ty::TraitRef<'tcx>,
err: &mut Diagnostic,
);
) -> bool;

fn report_const_param_not_wf(
&self,
Expand Down Expand Up @@ -506,8 +506,9 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {

let mut err = struct_span_err!(self.tcx.sess, span, E0277, "{}", err_msg);

let mut suggested = false;
if is_try_conversion {
self.try_conversion_context(&obligation, trait_ref.skip_binder(), &mut err);
suggested = self.try_conversion_context(&obligation, trait_ref.skip_binder(), &mut err);
}

if is_try_conversion && let Some(ret_span) = self.return_type_span(&obligation) {
Expand Down Expand Up @@ -608,8 +609,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {

self.suggest_floating_point_literal(&obligation, &mut err, &trait_ref);
self.suggest_dereferencing_index(&obligation, &mut err, trait_predicate);
let mut suggested =
self.suggest_dereferences(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_dereferences(&obligation, &mut err, trait_predicate);
suggested |= self.suggest_fn_call(&obligation, &mut err, trait_predicate);
let impl_candidates = self.find_similar_impl_candidates(trait_predicate);
suggested = if let &[cand] = &impl_candidates[..] {
Expand Down Expand Up @@ -944,7 +944,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
obligation: &PredicateObligation<'tcx>,
trait_ref: ty::TraitRef<'tcx>,
err: &mut Diagnostic,
) {
) -> bool {
let span = obligation.cause.span;
struct V<'v> {
search_span: Span,
Expand All @@ -969,22 +969,22 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
Some(hir::Node::Item(hir::Item { kind: hir::ItemKind::Fn(_, _, body_id), .. })) => {
body_id
}
_ => return,
_ => return false,
};
let mut v = V { search_span: span, found: None };
v.visit_body(self.tcx.hir().body(*body_id));
let Some(expr) = v.found else {
return;
return false;
};
let Some(typeck) = &self.typeck_results else {
return;
return false;
};
let Some((ObligationCauseCode::QuestionMark, Some(y))) = obligation.cause.code().parent()
else {
return;
return false;
};
if !self.tcx.is_diagnostic_item(sym::FromResidual, y.def_id()) {
return;
return false;
}
let self_ty = trait_ref.self_ty();
let found_ty = trait_ref.args.get(1).and_then(|a| a.as_type());
Expand All @@ -1009,6 +1009,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
Some(arg.as_type()?)
};

let mut suggested = false;
let mut chain = vec![];

// The following logic is simlar to `point_at_chain`, but that's focused on associated types
Expand Down Expand Up @@ -1073,6 +1074,7 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
)
.must_apply_modulo_regions()
{
suggested = true;
err.span_suggestion_short(
stmt.span.with_lo(expr.span.hi()),
"remove this semicolon",
Expand Down Expand Up @@ -1129,17 +1131,20 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
)
.must_apply_modulo_regions()
{
err.span_label(span, format!("this has type `Result<_, {err_ty}>`"));
if !suggested {
err.span_label(span, format!("this has type `Result<_, {err_ty}>`"));
}
} else {
err.span_label(
span,
format!(
"this can't be annotated with `?` because it has type `Result<_, {err_ty}>`",
),
);
span,
format!(
"this can't be annotated with `?` because it has type `Result<_, {err_ty}>`",
),
);
}
prev = Some(err_ty);
}
suggested
}

fn report_const_param_not_wf(
Expand Down
6 changes: 1 addition & 5 deletions tests/ui/traits/question-mark-result-err-mismatch.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ fn foo() -> Result<String, String> { //~ NOTE expected `String` because of this
let x = test
.split_whitespace()
.next()
.ok_or_else(|| { //~ NOTE this has type `Result<_, &str>`
.ok_or_else(|| {
"Couldn't split the test string"
});
let one = x
Expand All @@ -15,11 +15,9 @@ fn foo() -> Result<String, String> { //~ NOTE expected `String` because of this
//~^ NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the trait `From<()>` is not implemented for `String`
//~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
//~| NOTE required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>`
//~| HELP the following other types implement trait `From<T>`:
Ok(one.to_string())
}

Expand Down Expand Up @@ -52,11 +50,9 @@ fn baz() -> Result<String, String> { //~ NOTE expected `String` because of this
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE in this expansion of desugaring of operator `?`
//~| NOTE the trait `From<()>` is not implemented for `String`
//~| NOTE the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
//~| NOTE required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>`
//~| HELP the following other types implement trait `From<T>`:
Ok(one.to_string())
}

Expand Down
24 changes: 2 additions & 22 deletions tests/ui/traits/question-mark-result-err-mismatch.stderr
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,12 +4,6 @@ error[E0277]: `?` couldn't convert the error to `String`
LL | fn foo() -> Result<String, String> {
| ---------------------- expected `String` because of this
...
LL | .ok_or_else(|| {
| __________-
LL | | "Couldn't split the test string"
LL | | });
| |__________- this has type `Result<_, &str>`
...
LL | .map_err(|e| {
| __________-
LL | | e;
Expand All @@ -20,17 +14,10 @@ LL | .map(|()| "")?;
| ^ the trait `From<()>` is not implemented for `String`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= help: the following other types implement trait `From<T>`:
<String as From<char>>
<String as From<Box<str>>>
<String as From<Cow<'a, str>>>
<String as From<&str>>
<String as From<&mut str>>
<String as From<&String>>
= note: required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>`

error[E0277]: `?` couldn't convert the error to `String`
--> $DIR/question-mark-result-err-mismatch.rs:30:25
--> $DIR/question-mark-result-err-mismatch.rs:28:25
|
LL | fn bar() -> Result<(), String> {
| ------------------ expected `String` because of this
Expand All @@ -53,7 +40,7 @@ LL | .map_err(|_| ())?;
= note: required for `Result<(), String>` to implement `FromResidual<Result<Infallible, ()>>`

error[E0277]: `?` couldn't convert the error to `String`
--> $DIR/question-mark-result-err-mismatch.rs:50:11
--> $DIR/question-mark-result-err-mismatch.rs:48:11
|
LL | fn baz() -> Result<String, String> {
| ---------------------- expected `String` because of this
Expand All @@ -68,13 +55,6 @@ LL | | })?;
| this can't be annotated with `?` because it has type `Result<_, ()>`
|
= note: the question mark operation (`?`) implicitly performs a conversion on the error value using the `From` trait
= help: the following other types implement trait `From<T>`:
<String as From<char>>
<String as From<Box<str>>>
<String as From<Cow<'a, str>>>
<String as From<&str>>
<String as From<&mut str>>
<String as From<&String>>
= note: required for `Result<String, String>` to implement `FromResidual<Result<Infallible, ()>>`

error: aborting due to 3 previous errors
Expand Down

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