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More accurately handle suggestions

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* Confirm the path segment being modified is an `enum`
* Check whether type has type param before suggesting changing `Self`
* Wording changes
* Add clarifying comments
* Suggest removing args from `Self` if the type doesn't have type params
This commit is contained in:
Esteban Küber 2022-05-31 12:53:52 -07:00
parent 9b2d80a197
commit 532671b8ee
3 changed files with 106 additions and 54 deletions
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90
compiler/rustc_typeck/src/astconv/mod.rs
View File

@ -1803,52 +1803,84 @@ pub fn associated_path_to_ty(
tcx.check_stability(variant_def.def_id, Some(hir_ref_id), span, None);
self.prohibit_generics(slice::from_ref(assoc_segment).iter(), |err| {
err.note("enum variants can't have type parameters");
let type_name = tcx.opt_item_name(adt_def.did());
let the_enum = type_name.map(|n| format!("enum `{n}`")).unwrap_or_else(|| "the enum".to_string());
let msg = format!("you might have meant to specity type parameters on {the_enum}");
let type_name = tcx.item_name(adt_def.did());
let msg = format!(
"you might have meant to specity type parameters on enum \
`{type_name}`"
);
let Some(args) = assoc_segment.args else { return; };
// Get the span of the generics args *including* the leading `::`.
let args_span = assoc_segment.ident.span.shrink_to_hi().to(args.span_ext);
if tcx.generics_of(adt_def.did()).count() == 0 {
// FIXME(estebank): we could also verify that the arguments being
// work for the `enum`, instead of just looking if it takes *any*.
err.span_suggestion_verbose(
args_span,
&format!("{type_name} doesn't have type parameters"),
String::new(),
Applicability::MachineApplicable,
);
return;
}
let Ok(snippet) = tcx.sess.source_map().span_to_snippet(args_span) else {
err.note(&msg);
return;
};
let (qself_sugg_span, is_self) = if let hir::TyKind::Path(hir::QPath::Resolved(_, ref path)) = qself.kind {
let (qself_sugg_span, is_self) = if let hir::TyKind::Path(
hir::QPath::Resolved(_, ref path)
) = qself.kind {
// If the path segment already has type params, we want to overwrite
// them.
match &path.segments[..] {
[.., segment, _] => (
segment.ident.span.shrink_to_hi().to(segment.args.map_or(
segment.ident.span.shrink_to_hi(),
// `segment` is the previous to last element on the path,
// which would normally be the `enum` itself, while the last
// `_` `PathSegment` corresponds to the variant.
[.., hir::PathSegment {
ident,
args,
res: Some(Res::Def(DefKind::Enum, _)),
..
}, _] => (
// We need to include the `::` in `Type::Variant::<Args>`
// to point the span to `::<Args>`, not just `<Args>`.
ident.span.shrink_to_hi().to(args.map_or(
ident.span.shrink_to_hi(),
|a| a.span_ext)),
false,
),
[segment] => (
// We need to include the `::` in `Type::Variant::<Args>`
// to point the span to `::<Args>`, not just `<Args>`.
segment.ident.span.shrink_to_hi().to(segment.args.map_or(
segment.ident.span.shrink_to_hi(),
|a| a.span_ext)),
kw::SelfUpper == segment.ident.name,
),
_ => unreachable!(),
}
} else {
_ => {
err.note(&msg);
return;
};
let Some(type_name) = type_name else {
}
}
} else {
err.note(&msg);
return;
};
let suggestion = vec![
if is_self {
// Account for people writing `Self::Variant::<Args>`, where
// `Self` is the enum.
// `Self` is the enum, and suggest replacing `Self` with the
// appropriate type: `Type::<Args>::Variant`.
(qself.span, format!("{type_name}{snippet}"))
} else {
(qself_sugg_span, snippet)
},
(args_span, String::new()),
];
err.multipart_suggestion_verbose(&msg, suggestion, Applicability::MaybeIncorrect);
err.multipart_suggestion_verbose(
&msg,
suggestion,
Applicability::MaybeIncorrect,
);
});
return Ok((qself_ty, DefKind::Variant, variant_def.def_id));
} else {
@ -2369,8 +2401,6 @@ pub fn res_to_ty(
// Try to evaluate any array length constants.
let ty = tcx.at(span).type_of(def_id);
let span_of_impl = tcx.span_of_impl(def_id);
// TODO: confirm that `def_id`'s type accepts type params at all before suggesting
// using that instead.
self.prohibit_generics(path.segments.iter(), |err| {
let def_id = match *ty.kind() {
ty::Adt(self_def, _) => self_def.did(),
@ -2379,22 +2409,41 @@ pub fn res_to_ty(
let type_name = tcx.item_name(def_id);
let span_of_ty = tcx.def_ident_span(def_id);
let generics = tcx.generics_of(def_id).count();
let msg = format!("the `Self` type is `{ty}`");
let msg = format!("`Self` is of type `{ty}`");
if let (Ok(i_sp), Some(t_sp)) = (span_of_impl, span_of_ty) {
let i_sp = tcx.sess.source_map().guess_head_span(i_sp);
let mut span: MultiSpan = vec![t_sp].into();
span.push_span_label(
i_sp,
&format!("`Self` is `{type_name}` in this `impl`"),
&format!("`Self` is or type `{type_name}` in this `impl`"),
);
let mut postfix = "";
if generics == 0 {
postfix = ", which doesn't have type parameters";
}
span.push_span_label(
t_sp,
&format!("`Self` corresponds to this type{postfix}"),
);
span.push_span_label(t_sp, "`Self` corresponds to this type");
err.span_note(span, &msg);
} else {
err.note(&msg);
}
for segment in path.segments {
if let Some(_args) = segment.args && segment.ident.name == kw::SelfUpper {
if let Some(args) = segment.args && segment.ident.name == kw::SelfUpper {
if generics == 0 {
// FIXME(estebank): we could also verify that the arguments being
// work for the `enum`, instead of just looking if it takes *any*.
err.span_suggestion_verbose(
segment.ident.span.shrink_to_hi().to(args.span_ext),
"the `Self` type doesn't accept type parameters",
String::new(),
Applicability::MachineApplicable,
);
return;
} else {
err.span_suggestion_verbose(
segment.ident.span,
format!(
@ -2407,6 +2456,7 @@ pub fn res_to_ty(
);
}
}
}
});
// HACK(min_const_generics): Forbid generic `Self` types
// here as we can't easily do that during nameres.

26
src/test/ui/structs/struct-path-self.stderr
View File

@ -34,18 +34,19 @@ error[E0109]: type arguments are not allowed for this type
LL | let z = Self::<u8> {};
| ^^ type argument not allowed
|
note: the `Self` type is `S`
note: `Self` is of type `S`
--> $DIR/struct-path-self.rs:1:8
|
LL | struct S;
| ^ `Self` corresponds to this type
| ^ `Self` corresponds to this type, which doesn't have type parameters
...
LL | impl Tr for S {
| ------------- `Self` is `S` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `S` instead if you want to specify its type parameters
| ------------- `Self` is or type `S` in this `impl`
help: the `Self` type doesn't accept type parameters
|
LL - let z = Self::<u8> {};
LL + let z = Self {};
|
LL | let z = S::<u8> {};
| ~
error[E0109]: type arguments are not allowed for this type
--> $DIR/struct-path-self.rs:30:24
@ -53,18 +54,19 @@ error[E0109]: type arguments are not allowed for this type
LL | let z = Self::<u8> {};
| ^^ type argument not allowed
|
note: the `Self` type is `S`
note: `Self` is of type `S`
--> $DIR/struct-path-self.rs:1:8
|
LL | struct S;
| ^ `Self` corresponds to this type
| ^ `Self` corresponds to this type, which doesn't have type parameters
...
LL | impl S {
| ------ `Self` is `S` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `S` instead if you want to specify its type parameters
| ------ `Self` is or type `S` in this `impl`
help: the `Self` type doesn't accept type parameters
|
LL - let z = Self::<u8> {};
LL + let z = Self {};
|
LL | let z = S::<u8> {};
| ~
error: aborting due to 6 previous errors

24
src/test/ui/type-alias-enum-variants/enum-variant-generic-args.stderr
View File

@ -29,14 +29,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::TSVariant(());
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::TSVariant(());
@ -67,14 +67,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::TSVariant::<()>(());
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::TSVariant::<()>(());
@ -129,14 +129,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::SVariant { v: () };
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::SVariant { v: () };
@ -160,14 +160,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::SVariant::<()> { v: () };
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::SVariant::<()> { v: () };
@ -210,14 +210,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::UVariant;
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::UVariant;
@ -229,14 +229,14 @@ error[E0109]: type arguments are not allowed for this type
LL | Self::<()>::UVariant::<()>;
| ^^ type argument not allowed
|
note: the `Self` type is `Enum<T>`
note: `Self` is of type `Enum<T>`
--> $DIR/enum-variant-generic-args.rs:7:6
|
LL | enum Enum<T> { TSVariant(T), SVariant { v: T }, UVariant }
| ^^^^ `Self` corresponds to this type
...
LL | impl<T> Enum<T> {
| --------------- `Self` is `Enum` in this `impl`
| --------------- `Self` is or type `Enum` in this `impl`
help: the `Self` type doesn't accept type parameters, use the concrete type's name `Enum` instead if you want to specify its type parameters
|
LL | Enum::<()>::UVariant::<()>;