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Add hint for unresolved associated trait items if the trait has a single item

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This commit is contained in:
Jakub Beránek 2021-08-04 23:29:30 +02:00
parent 6be8a06bcf
commit d0d4947775
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GPG Key ID: DBC553E540C2F619
7 changed files with 172 additions and 28 deletions
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62
compiler/rustc_resolve/src/diagnostics.rs
View File

@ -38,14 +38,25 @@ crate type Suggestion = (Vec<(Span, String)>, String, Applicability);
/// similarly named label and whether or not it is reachable.
crate type LabelSuggestion = (Ident, bool);
crate enum SuggestionTarget {
/// The target has a similar name as the name used by the programmer (probably a typo)
SimilarlyNamed,
/// The target is the only valid item that can be used in the corresponding context
SingleItem,
}
crate struct TypoSuggestion {
pub candidate: Symbol,
pub res: Res,
pub target: SuggestionTarget,
}
impl TypoSuggestion {
crate fn from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
TypoSuggestion { candidate, res }
crate fn typo_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
Self { candidate, res, target: SuggestionTarget::SimilarlyNamed }
}
crate fn single_item_from_res(candidate: Symbol, res: Res) -> TypoSuggestion {
Self { candidate, res, target: SuggestionTarget::SingleItem }
}
}
@ -80,7 +91,7 @@ impl<'a> Resolver<'a> {
if let Some(binding) = resolution.borrow().binding {
let res = binding.res();
if filter_fn(res) {
names.push(TypoSuggestion::from_res(key.ident.name, res));
names.push(TypoSuggestion::typo_from_res(key.ident.name, res));
}
}
}
@ -623,7 +634,7 @@ impl<'a> Resolver<'a> {
.get(&expn_id)
.into_iter()
.flatten()
.map(|ident| TypoSuggestion::from_res(ident.name, res)),
.map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
);
}
}
@ -642,7 +653,7 @@ impl<'a> Resolver<'a> {
suggestions.extend(
ext.helper_attrs
.iter()
.map(|name| TypoSuggestion::from_res(*name, res)),
.map(|name| TypoSuggestion::typo_from_res(*name, res)),
);
}
}
@ -652,8 +663,10 @@ impl<'a> Resolver<'a> {
if let MacroRulesScope::Binding(macro_rules_binding) = macro_rules_scope.get() {
let res = macro_rules_binding.binding.res();
if filter_fn(res) {
suggestions
.push(TypoSuggestion::from_res(macro_rules_binding.ident.name, res))
suggestions.push(TypoSuggestion::typo_from_res(
macro_rules_binding.ident.name,
res,
))
}
}
}
@ -671,7 +684,7 @@ impl<'a> Resolver<'a> {
suggestions.extend(
this.registered_attrs
.iter()
.map(|ident| TypoSuggestion::from_res(ident.name, res)),
.map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
);
}
}
@ -679,7 +692,7 @@ impl<'a> Resolver<'a> {
suggestions.extend(this.macro_use_prelude.iter().filter_map(
|(name, binding)| {
let res = binding.res();
filter_fn(res).then_some(TypoSuggestion::from_res(*name, res))
filter_fn(res).then_some(TypoSuggestion::typo_from_res(*name, res))
},
));
}
@ -689,14 +702,14 @@ impl<'a> Resolver<'a> {
suggestions.extend(
BUILTIN_ATTRIBUTES
.iter()
.map(|(name, ..)| TypoSuggestion::from_res(*name, res)),
.map(|(name, ..)| TypoSuggestion::typo_from_res(*name, res)),
);
}
}
Scope::ExternPrelude => {
suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| {
let res = Res::Def(DefKind::Mod, DefId::local(CRATE_DEF_INDEX));
filter_fn(res).then_some(TypoSuggestion::from_res(ident.name, res))
filter_fn(res).then_some(TypoSuggestion::typo_from_res(ident.name, res))
}));
}
Scope::ToolPrelude => {
@ -704,7 +717,7 @@ impl<'a> Resolver<'a> {
suggestions.extend(
this.registered_tools
.iter()
.map(|ident| TypoSuggestion::from_res(ident.name, res)),
.map(|ident| TypoSuggestion::typo_from_res(ident.name, res)),
);
}
Scope::StdLibPrelude => {
@ -721,7 +734,7 @@ impl<'a> Resolver<'a> {
Scope::BuiltinTypes => {
suggestions.extend(PrimTy::ALL.iter().filter_map(|prim_ty| {
let res = Res::PrimTy(*prim_ty);
filter_fn(res).then_some(TypoSuggestion::from_res(prim_ty.name(), res))
filter_fn(res).then_some(TypoSuggestion::typo_from_res(prim_ty.name(), res))
}))
}
}
@ -993,20 +1006,31 @@ impl<'a> Resolver<'a> {
// | ^
return false;
}
let prefix = match suggestion.target {
SuggestionTarget::SimilarlyNamed => "similarly named ",
SuggestionTarget::SingleItem => "",
};
err.span_label(
self.session.source_map().guess_head_span(def_span),
&format!(
"similarly named {} `{}` defined here",
"{}{} `{}` defined here",
prefix,
suggestion.res.descr(),
suggestion.candidate.as_str(),
),
);
}
let msg = format!(
"{} {} with a similar name exists",
suggestion.res.article(),
suggestion.res.descr()
);
let msg = match suggestion.target {
SuggestionTarget::SimilarlyNamed => format!(
"{} {} with a similar name exists",
suggestion.res.article(),
suggestion.res.descr()
),
SuggestionTarget::SingleItem => {
format!("maybe you meant this {}", suggestion.res.descr())
}
};
err.span_suggestion(
span,
&msg,

52
compiler/rustc_resolve/src/late/diagnostics.rs
View File

@ -541,6 +541,10 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
}
_ => {}
}
// If the trait has a single item (which wasn't matched by Levenshtein), suggest it
let suggestion = self.get_single_associated_item(&path, span, &source, is_expected);
self.r.add_typo_suggestion(&mut err, suggestion, ident_span);
}
if fallback {
// Fallback label.
@ -585,6 +589,40 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
(err, candidates)
}
fn get_single_associated_item(
&mut self,
path: &[Segment],
span: Span,
source: &PathSource<'_>,
filter_fn: &impl Fn(Res) -> bool,
) -> Option<TypoSuggestion> {
if let crate::PathSource::TraitItem(_) = source {
let mod_path = &path[..path.len() - 1];
if let PathResult::Module(ModuleOrUniformRoot::Module(module)) =
self.resolve_path(mod_path, None, false, span, CrateLint::No)
{
let resolutions = self.r.resolutions(module).borrow();
let targets: Vec<_> =
resolutions
.iter()
.filter_map(|(key, resolution)| {
resolution.borrow().binding.map(|binding| binding.res()).and_then(
|res| if filter_fn(res) { Some((key, res)) } else { None },
)
})
.collect();
if targets.len() == 1 {
let target = targets[0];
return Some(TypoSuggestion::single_item_from_res(
target.0.ident.name,
target.1,
));
}
}
}
None
}
/// Given `where <T as Bar>::Baz: String`, suggest `where T: Bar<Baz = String>`.
fn restrict_assoc_type_in_where_clause(
&mut self,
@ -1208,7 +1246,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
// Locals and type parameters
for (ident, &res) in &rib.bindings {
if filter_fn(res) {
names.push(TypoSuggestion::from_res(ident.name, res));
names.push(TypoSuggestion::typo_from_res(ident.name, res));
}
}
// Items in scope
@ -1231,7 +1269,9 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
);
if filter_fn(crate_mod) {
Some(TypoSuggestion::from_res(ident.name, crate_mod))
Some(TypoSuggestion::typo_from_res(
ident.name, crate_mod,
))
} else {
None
}
@ -1249,11 +1289,9 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
}
// Add primitive types to the mix
if filter_fn(Res::PrimTy(PrimTy::Bool)) {
names.extend(
PrimTy::ALL.iter().map(|prim_ty| {
TypoSuggestion::from_res(prim_ty.name(), Res::PrimTy(*prim_ty))
}),
)
names.extend(PrimTy::ALL.iter().map(|prim_ty| {
TypoSuggestion::typo_from_res(prim_ty.name(), Res::PrimTy(*prim_ty))
}))
}
} else {
// Search in module.

22
src/test/ui/associated-item/issue-87638.fixed Normal file
View File

@ -0,0 +1,22 @@
// run-rustfix
trait Trait {
const FOO: usize;
type Target;
}
struct S;
impl Trait for S {
const FOO: usize = 0;
type Target = ();
}
fn main() {
let _: <S as Trait>::Target; //~ ERROR cannot find associated type `Output` in trait `Trait`
//~^ HELP maybe you meant this associated type
let _ = <S as Trait>::FOO; //~ ERROR cannot find method or associated constant `BAR` in trait `Trait`
//~^ HELP maybe you meant this associated constant
}

22
src/test/ui/associated-item/issue-87638.rs Normal file
View File

@ -0,0 +1,22 @@
// run-rustfix
trait Trait {
const FOO: usize;
type Target;
}
struct S;
impl Trait for S {
const FOO: usize = 0;
type Target = ();
}
fn main() {
let _: <S as Trait>::Output; //~ ERROR cannot find associated type `Output` in trait `Trait`
//~^ HELP maybe you meant this associated type
let _ = <S as Trait>::BAR; //~ ERROR cannot find method or associated constant `BAR` in trait `Trait`
//~^ HELP maybe you meant this associated constant
}

27
src/test/ui/associated-item/issue-87638.stderr Normal file
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@ -0,0 +1,27 @@
error[E0576]: cannot find associated type `Output` in trait `Trait`
--> $DIR/issue-87638.rs:17:26
|
LL | type Target;
| ------------ associated type `Target` defined here
...
LL | let _: <S as Trait>::Output;
| ^^^^^^
| |
| not found in `Trait`
| help: maybe you meant this associated type: `Target`
error[E0576]: cannot find method or associated constant `BAR` in trait `Trait`
--> $DIR/issue-87638.rs:20:27
|
LL | const FOO: usize;
| ----------------- associated constant `FOO` defined here
...
LL | let _ = <S as Trait>::BAR;
| ^^^
| |
| not found in `Trait`
| help: maybe you meant this associated constant: `FOO`
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0576`.

7
src/test/ui/associated-types/issue-22037.stderr
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@ -1,8 +1,13 @@
error[E0576]: cannot find associated type `X` in trait `A`
--> $DIR/issue-22037.rs:3:33
|
LL | type Output;
| ------------ associated type `Output` defined here
LL | fn a(&self) -> <Self as A>::X;
| ^ not found in `A`
| ^
| |
| not found in `A`
| help: maybe you meant this associated type: `Output`
error: aborting due to previous error

8
src/test/ui/issues/issue-19883.stderr
View File

@ -1,8 +1,14 @@
error[E0576]: cannot find associated type `Dst` in trait `From`
--> $DIR/issue-19883.rs:9:30
|
LL | type Output;
| ------------ associated type `Output` defined here
...
LL | <Dst as From<Self>>::Dst
| ^^^ not found in `From`
| ^^^
| |
| not found in `From`
| help: maybe you meant this associated type: `Output`
error: aborting due to previous error