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Rollup merge of #77855 - davidtwco:pr-77341-follow-up-non-constructable-variants, r=estebank

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resolve: further improvements to "try using the enum's variant" diagnostic

Follow-up on https://github.com/rust-lang/rust/pull/77341#issuecomment-702738281.

This PR improves the diagnostic modified in #77341 to suggest not only those variants which do not have fields, but those with fields (by suggesting with placeholders). In addition, the wording of the tuple-variant-only case is improved slightly.

I've not made further changes to the tuple-variant-only case (e.g. to only suggest variants with the correct number of fields) because I don't think I have enough information to do so reliably (e.g. in the case where there is an attempt to construct a tuple variant, I have no information on how many fields were provided; and in the case of pattern matching, I only have a slice of spans and would need to check for things like `..` in those spans, which doesn't seem worth it).

r? @estebank
This commit is contained in:
Yuki Okushi 2020-10-17 05:36:43 +09:00 • committed by GitHub
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5 changed files with 318 additions and 85 deletions
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150
compiler/rustc_resolve/src/late/diagnostics.rs
View file

@ -1330,58 +1330,17 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
let suggest_only_tuple_variants =
matches!(source, PathSource::TupleStruct(..)) || source.is_call();
let mut suggestable_variants = if suggest_only_tuple_variants {
if suggest_only_tuple_variants {
// Suggest only tuple variants regardless of whether they have fields and do not
// suggest path with added parenthesis.
variants
let mut suggestable_variants = variants
.iter()
.filter(|(.., kind)| *kind == CtorKind::Fn)
.map(|(variant, ..)| path_names_to_string(variant))
.collect::<Vec<_>>()
} else {
variants
.iter()
.filter(|(_, def_id, kind)| {
// Suggest only variants that have no fields (these can definitely
// be constructed).
let has_fields =
self.r.field_names.get(&def_id).map(|f| f.is_empty()).unwrap_or(false);
match kind {
CtorKind::Const => true,
CtorKind::Fn | CtorKind::Fictive if has_fields => true,
_ => false,
}
})
.map(|(variant, _, kind)| (path_names_to_string(variant), kind))
.map(|(variant_str, kind)| {
// Add constructor syntax where appropriate.
match kind {
CtorKind::Const => variant_str,
CtorKind::Fn => format!("({}())", variant_str),
CtorKind::Fictive => format!("({} {{}})", variant_str),
}
})
.collect::<Vec<_>>()
};
.collect::<Vec<_>>();
let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
let non_suggestable_variant_count = variants.len() - suggestable_variants.len();
if !suggestable_variants.is_empty() {
let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
"try using the enum's variant"
} else {
"try using one of the enum's variants"
};
err.span_suggestions(
span,
msg,
suggestable_variants.drain(..),
Applicability::MaybeIncorrect,
);
}
if suggest_only_tuple_variants {
let source_msg = if source.is_call() {
"to construct"
} else if matches!(source, PathSource::TupleStruct(..)) {
@ -1390,6 +1349,21 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
unreachable!()
};
if !suggestable_variants.is_empty() {
let msg = if non_suggestable_variant_count == 0 && suggestable_variants.len() == 1 {
format!("try {} the enum's variant", source_msg)
} else {
format!("try {} one of the enum's variants", source_msg)
};
err.span_suggestions(
span,
&msg,
suggestable_variants.drain(..),
Applicability::MaybeIncorrect,
);
}
// If the enum has no tuple variants..
if non_suggestable_variant_count == variants.len() {
err.help(&format!("the enum has no tuple variants {}", source_msg));
@ -1408,24 +1382,76 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
));
}
} else {
let made_suggestion = non_suggestable_variant_count != variants.len();
if made_suggestion {
if non_suggestable_variant_count == 1 {
err.help(
"you might have meant to use the enum's other variant that has fields",
);
} else if non_suggestable_variant_count >= 1 {
err.help(
"you might have meant to use one of the enum's other variants that \
have fields",
);
}
} else {
if non_suggestable_variant_count == 1 {
err.help("you might have meant to use the enum's variant");
} else if non_suggestable_variant_count >= 1 {
err.help("you might have meant to use one of the enum's variants");
let needs_placeholder = |def_id: DefId, kind: CtorKind| {
let has_no_fields =
self.r.field_names.get(&def_id).map(|f| f.is_empty()).unwrap_or(false);
match kind {
CtorKind::Const => false,
CtorKind::Fn | CtorKind::Fictive if has_no_fields => false,
_ => true,
}
};
let mut suggestable_variants = variants
.iter()
.filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind))
.map(|(variant, _, kind)| (path_names_to_string(variant), kind))
.map(|(variant, kind)| match kind {
CtorKind::Const => variant,
CtorKind::Fn => format!("({}())", variant),
CtorKind::Fictive => format!("({} {{}})", variant),
})
.collect::<Vec<_>>();
if !suggestable_variants.is_empty() {
let msg = if suggestable_variants.len() == 1 {
"you might have meant to use the following enum variant"
} else {
"you might have meant to use one of the following enum variants"
};
err.span_suggestions(
span,
msg,
suggestable_variants.drain(..),
Applicability::MaybeIncorrect,
);
}
let mut suggestable_variants_with_placeholders = variants
.iter()
.filter(|(_, def_id, kind)| needs_placeholder(*def_id, *kind))
.map(|(variant, _, kind)| (path_names_to_string(variant), kind))
.filter_map(|(variant, kind)| match kind {
CtorKind::Fn => Some(format!("({}(/* fields */))", variant)),
CtorKind::Fictive => Some(format!("({} {{ /* fields */ }})", variant)),
_ => None,
})
.collect::<Vec<_>>();
if !suggestable_variants_with_placeholders.is_empty() {
let msg = match (
suggestable_variants.is_empty(),
suggestable_variants_with_placeholders.len(),
) {
(true, 1) => "the following enum variant is available",
(true, _) => "the following enum variants are available",
(false, 1) => "alternatively, the following enum variant is available",
(false, _) => "alternatively, the following enum variants are also available",
};
err.span_suggestions(
span,
msg,
suggestable_variants_with_placeholders.drain(..),
Applicability::HasPlaceholders,
);
}
};
if def_id.is_local() {
if let Some(span) = self.def_span(def_id) {
err.span_note(span, "the enum is defined here");
}
}
}

27
src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr
View file

@ -2,7 +2,7 @@ error[E0423]: expected function, tuple struct or tuple variant, found enum `Opti
--> $DIR/issue-43871-enum-instead-of-variant.rs:19:13
|
LL | let x = Option(1);
| ^^^^^^ help: try using one of the enum's variants: `std::option::Option::Some`
| ^^^^^^ help: try to construct one of the enum's variants: `std::option::Option::Some`
|
= help: you might have meant to construct the enum's non-tuple variant
@ -10,7 +10,7 @@ error[E0532]: expected tuple struct or tuple variant, found enum `Option`
--> $DIR/issue-43871-enum-instead-of-variant.rs:21:12
|
LL | if let Option(_) = x {
| ^^^^^^ help: try using one of the enum's variants: `std::option::Option::Some`
| ^^^^^^ help: try to match against one of the enum's variants: `std::option::Option::Some`
|
= help: you might have meant to match against the enum's non-tuple variant
@ -18,9 +18,14 @@ error[E0532]: expected tuple struct or tuple variant, found enum `Example`
--> $DIR/issue-43871-enum-instead-of-variant.rs:27:12
|
LL | if let Example(_) = y {
| ^^^^^^^ help: try using one of the enum's variants: `Example::Ex`
| ^^^^^^^ help: try to match against one of the enum's variants: `Example::Ex`
|
= help: you might have meant to match against the enum's non-tuple variant
note: the enum is defined here
--> $DIR/issue-43871-enum-instead-of-variant.rs:1:1
|
LL | enum Example { Ex(String), NotEx }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected function, tuple struct or tuple variant, found enum `Void`
--> $DIR/issue-43871-enum-instead-of-variant.rs:31:13
@ -29,6 +34,11 @@ LL | let y = Void();
| ^^^^
|
= help: the enum has no tuple variants to construct
note: the enum is defined here
--> $DIR/issue-43871-enum-instead-of-variant.rs:3:1
|
LL | enum Void {}
| ^^^^^^^^^^^^
error[E0423]: expected function, tuple struct or tuple variant, found enum `ManyVariants`
--> $DIR/issue-43871-enum-instead-of-variant.rs:33:13
@ -38,6 +48,17 @@ LL | let z = ManyVariants();
|
= help: the enum has no tuple variants to construct
= help: you might have meant to construct one of the enum's non-tuple variants
note: the enum is defined here
--> $DIR/issue-43871-enum-instead-of-variant.rs:5:1
|
LL | / enum ManyVariants {
LL | | One,
LL | | Two,
LL | | Three,
... |
LL | | Ten,
LL | | }
| |_^
error: aborting due to 5 previous errors

12
src/test/ui/glob-resolve1.stderr
View file

@ -24,7 +24,17 @@ error[E0423]: expected value, found enum `B`
--> $DIR/glob-resolve1.rs:24:5
|
LL | B;
| ^ help: try using the enum's variant: `B::B1`
| ^
|
note: the enum is defined here
--> $DIR/glob-resolve1.rs:12:5
|
LL | pub enum B { B1 }
| ^^^^^^^^^^^^^^^^^
help: you might have meant to use the following enum variant
|
LL | B::B1;
| ^^^^^
error[E0425]: cannot find value `C` in this scope
--> $DIR/glob-resolve1.rs:25:5

102
src/test/ui/issues/issue-73427.stderr
View file

@ -4,8 +4,18 @@ error[E0423]: expected value, found enum `A`
LL | A.foo();
| ^
|
= help: you might have meant to use one of the enum's other variants that have fields
help: try using one of the enum's variants
note: the enum is defined here
--> $DIR/issue-73427.rs:1:1
|
LL | / enum A {
LL | | StructWithFields { x: () },
LL | | TupleWithFields(()),
LL | | Struct {},
LL | | Tuple(),
LL | | Unit,
LL | | }
| |_^
help: you might have meant to use one of the following enum variants
|
LL | (A::Struct {}).foo();
| ^^^^^^^^^^^^^^
@ -13,6 +23,12 @@ LL | (A::Tuple()).foo();
| ^^^^^^^^^^^^
LL | A::Unit.foo();
| ^^^^^^^
help: the following enum variants are available
|
LL | (A::StructWithFields { /* fields */ }).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | (A::TupleWithFields(/* fields */)).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected value, found enum `B`
--> $DIR/issue-73427.rs:31:5
@ -20,23 +36,69 @@ error[E0423]: expected value, found enum `B`
LL | B.foo();
| ^
|
= help: you might have meant to use one of the enum's variants
note: the enum is defined here
--> $DIR/issue-73427.rs:9:1
|
LL | / enum B {
LL | | StructWithFields { x: () },
LL | | TupleWithFields(()),
LL | | }
| |_^
help: the following enum variants are available
|
LL | (B::StructWithFields { /* fields */ }).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | (B::TupleWithFields(/* fields */)).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected value, found enum `C`
--> $DIR/issue-73427.rs:33:5
|
LL | C.foo();
| ^ help: try using one of the enum's variants: `C::Unit`
| ^
|
= help: you might have meant to use one of the enum's other variants that have fields
note: the enum is defined here
--> $DIR/issue-73427.rs:14:1
|
LL | / enum C {
LL | | StructWithFields { x: () },
LL | | TupleWithFields(()),
LL | | Unit,
LL | | }
| |_^
help: you might have meant to use the following enum variant
|
LL | C::Unit.foo();
| ^^^^^^^
help: the following enum variants are available
|
LL | (C::StructWithFields { /* fields */ }).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | (C::TupleWithFields(/* fields */)).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected value, found enum `D`
--> $DIR/issue-73427.rs:35:5
|
LL | D.foo();
| ^ help: try using one of the enum's variants: `D::Unit`
| ^
|
= help: you might have meant to use the enum's other variant that has fields
note: the enum is defined here
--> $DIR/issue-73427.rs:20:1
|
LL | / enum D {
LL | | TupleWithFields(()),
LL | | Unit,
LL | | }
| |_^
help: you might have meant to use the following enum variant
|
LL | D::Unit.foo();
| ^^^^^^^
help: the following enum variant is available
|
LL | (D::TupleWithFields(/* fields */)).foo();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected function, tuple struct or tuple variant, found enum `A`
--> $DIR/issue-73427.rs:40:13
@ -45,7 +107,18 @@ LL | let x = A(3);
| ^
|
= help: you might have meant to construct one of the enum's non-tuple variants
help: try using one of the enum's variants
note: the enum is defined here
--> $DIR/issue-73427.rs:1:1
|
LL | / enum A {
LL | | StructWithFields { x: () },
LL | | TupleWithFields(()),
LL | | Struct {},
LL | | Tuple(),
LL | | Unit,
LL | | }
| |_^
help: try to construct one of the enum's variants
|
LL | let x = A::TupleWithFields(3);
| ^^^^^^^^^^^^^^^^^^
@ -59,7 +132,18 @@ LL | if let A(3) = x { }
| ^
|
= help: you might have meant to match against one of the enum's non-tuple variants
help: try using one of the enum's variants
note: the enum is defined here
--> $DIR/issue-73427.rs:1:1
|
LL | / enum A {
LL | | StructWithFields { x: () },
LL | | TupleWithFields(()),
LL | | Struct {},
LL | | Tuple(),
LL | | Unit,
LL | | }
| |_^
help: try to match against one of the enum's variants
|
LL | if let A::TupleWithFields(3) = x { }
| ^^^^^^^^^^^^^^^^^^

112
src/test/ui/resolve/privacy-enum-ctor.stderr
View file

@ -2,17 +2,57 @@ error[E0423]: expected value, found enum `n::Z`
--> $DIR/privacy-enum-ctor.rs:23:9
|
LL | n::Z;
| ^^^^ help: try using one of the enum's variants: `m::Z::Unit`
| ^^^^
|
= help: you might have meant to use one of the enum's other variants that have fields
note: the enum is defined here
--> $DIR/privacy-enum-ctor.rs:11:9
|
LL | / pub(in m) enum Z {
LL | | Fn(u8),
LL | | Struct {
LL | | s: u8,
LL | | },
LL | | Unit,
LL | | }
| |_________^
help: you might have meant to use the following enum variant
|
LL | m::Z::Unit;
| ^^^^^^^^^^
help: the following enum variants are available
|
LL | (m::Z::Fn(/* fields */));
| ^^^^^^^^^^^^^^^^^^^^^^^^
LL | (m::Z::Struct { /* fields */ });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected value, found enum `Z`
--> $DIR/privacy-enum-ctor.rs:25:9
|
LL | Z;
| ^ help: try using one of the enum's variants: `m::Z::Unit`
| ^
|
= help: you might have meant to use one of the enum's other variants that have fields
note: the enum is defined here
--> $DIR/privacy-enum-ctor.rs:11:9
|
LL | / pub(in m) enum Z {
LL | | Fn(u8),
LL | | Struct {
LL | | s: u8,
LL | | },
LL | | Unit,
LL | | }
| |_________^
help: you might have meant to use the following enum variant
|
LL | m::Z::Unit;
| ^^^^^^^^^^
help: the following enum variants are available
|
LL | (m::Z::Fn(/* fields */));
| ^^^^^^^^^^^^^^^^^^^^^^^^
LL | (m::Z::Struct { /* fields */ });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0423]: expected value, found struct variant `Z::Struct`
--> $DIR/privacy-enum-ctor.rs:29:20
@ -34,11 +74,27 @@ LL | fn f() {
LL | let _: E = m::E;
| ^^^^
|
= help: you might have meant to use one of the enum's other variants that have fields
help: try using one of the enum's variants
note: the enum is defined here
--> $DIR/privacy-enum-ctor.rs:2:5
|
LL | / pub enum E {
LL | | Fn(u8),
LL | | Struct {
LL | | s: u8,
LL | | },
LL | | Unit,
LL | | }
| |_____^
help: you might have meant to use the following enum variant
|
LL | let _: E = E::Unit;
| ^^^^^^^
help: the following enum variants are available
|
LL | let _: E = (E::Fn(/* fields */));
| ^^^^^^^^^^^^^^^^^^^^^
LL | let _: E = (E::Struct { /* fields */ });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: a function with a similar name exists
|
LL | let _: E = m::f;
@ -67,11 +123,27 @@ error[E0423]: expected value, found enum `E`
LL | let _: E = E;
| ^
|
= help: you might have meant to use one of the enum's other variants that have fields
help: try using one of the enum's variants
note: the enum is defined here
--> $DIR/privacy-enum-ctor.rs:2:5
|
LL | / pub enum E {
LL | | Fn(u8),
LL | | Struct {
LL | | s: u8,
LL | | },
LL | | Unit,
LL | | }
| |_____^
help: you might have meant to use the following enum variant
|
LL | let _: E = E::Unit;
| ^^^^^^^
help: the following enum variants are available
|
LL | let _: E = (E::Fn(/* fields */));
| ^^^^^^^^^^^^^^^^^^^^^
LL | let _: E = (E::Struct { /* fields */ });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: consider importing one of these items instead
|
LL | use std::f32::consts::E;
@ -112,9 +184,29 @@ error[E0423]: expected value, found enum `m::n::Z`
--> $DIR/privacy-enum-ctor.rs:57:16
|
LL | let _: Z = m::n::Z;
| ^^^^^^^ help: try using one of the enum's variants: `m::Z::Unit`
| ^^^^^^^
|
= help: you might have meant to use one of the enum's other variants that have fields
note: the enum is defined here
--> $DIR/privacy-enum-ctor.rs:11:9
|
LL | / pub(in m) enum Z {
LL | | Fn(u8),
LL | | Struct {
LL | | s: u8,
LL | | },
LL | | Unit,
LL | | }
| |_________^
help: you might have meant to use the following enum variant
|
LL | let _: Z = m::Z::Unit;
| ^^^^^^^^^^
help: the following enum variants are available
|
LL | let _: Z = (m::Z::Fn(/* fields */));
| ^^^^^^^^^^^^^^^^^^^^^^^^
LL | let _: Z = (m::Z::Struct { /* fields */ });
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error[E0412]: cannot find type `Z` in this scope
--> $DIR/privacy-enum-ctor.rs:61:12