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Improve diagnostics for const a: = expr;

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This commit is contained in:
Maybe Waffle 2022-08-05 15:41:42 +04:00
parent 1f5d8d49eb
commit 743ad07c4b
16 changed files with 109 additions and 66 deletions
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30
compiler/rustc_parse/src/parser/item.rs
View File

@ -1179,10 +1179,11 @@ impl<'a> Parser<'a> {
// Parse the type of a `const` or `static mut?` item.
// That is, the `":" $ty` fragment.
let ty = if self.eat(&token::Colon) {
self.parse_ty()?
} else {
self.recover_missing_const_type(id, m)
let ty = match (self.eat(&token::Colon), self.check(&token::Eq) | self.check(&token::Semi))
{
// If there wasn't a `:` or the colon was followed by a `=` or `;` recover a missing type.
(true, false) => self.parse_ty()?,
(colon, _) => self.recover_missing_const_type(colon, m),
};
let expr = if self.eat(&token::Eq) { Some(self.parse_expr()?) } else { None };
@ -1190,9 +1191,9 @@ impl<'a> Parser<'a> {
Ok((id, ty, expr))
}
/// We were supposed to parse `:` but the `:` was missing.
/// We were supposed to parse `":" $ty` but the `:` or the type was missing.
/// This means that the type is missing.
fn recover_missing_const_type(&mut self, id: Ident, m: Option<Mutability>) -> P<Ty> {
fn recover_missing_const_type(&mut self, colon_present: bool, m: Option<Mutability>) -> P<Ty> {
// Construct the error and stash it away with the hope
// that typeck will later enrich the error with a type.
let kind = match m {
@ -1200,18 +1201,25 @@ impl<'a> Parser<'a> {
Some(Mutability::Not) => "static",
None => "const",
};
let mut err = self.struct_span_err(id.span, &format!("missing type for `{kind}` item"));
let colon = match colon_present {
true => "",
false => ":",
};
let span = self.prev_token.span.shrink_to_hi();
let mut err = self.struct_span_err(span, &format!("missing type for `{kind}` item"));
err.span_suggestion(
id.span,
span,
"provide a type for the item",
format!("{id}: <type>"),
format!("{colon} <type>"),
Applicability::HasPlaceholders,
);
err.stash(id.span, StashKey::ItemNoType);
err.stash(span, StashKey::ItemNoType);
// The user intended that the type be inferred,
// so treat this as if the user wrote e.g. `const A: _ = expr;`.
P(Ty { kind: TyKind::Infer, span: id.span, id: ast::DUMMY_NODE_ID, tokens: None })
P(Ty { kind: TyKind::Infer, span, id: ast::DUMMY_NODE_ID, tokens: None })
}
/// Parses an enum declaration.

5
compiler/rustc_typeck/src/collect/type_of.rs
View File

@ -801,6 +801,9 @@ fn infer_placeholder_type<'a>(
match tcx.sess.diagnostic().steal_diagnostic(span, StashKey::ItemNoType) {
Some(mut err) => {
if !ty.references_error() {
// Only suggest adding `:` if it was missing (and suggested by parsing diagnostic)
let colon = if span == item_ident.span.shrink_to_hi() { ":" } else { "" };
// The parser provided a sub-optimal `HasPlaceholders` suggestion for the type.
// We are typeck and have the real type, so remove that and suggest the actual type.
// FIXME(eddyb) this looks like it should be functionality on `Diagnostic`.
@ -816,7 +819,7 @@ fn infer_placeholder_type<'a>(
err.span_suggestion(
span,
&format!("provide a type for the {item}", item = kind),
format!("{}: {}", item_ident, sugg_ty),
format!("{colon} {sugg_ty}"),
Applicability::MachineApplicable,
);
} else {

4
src/test/ui/attributes/issue-90873.stderr
View File

@ -34,10 +34,10 @@ LL | #![a={impl std::ops::Neg for i8 {}}]
| ^ consider adding a `main` function to `$DIR/issue-90873.rs`
error: missing type for `static` item
--> $DIR/issue-90873.rs:1:16
--> $DIR/issue-90873.rs:1:17
|
LL | #![u=||{static d=||1;}]
| ^ help: provide a type for the item: `d: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 6 previous errors

14
src/test/ui/issues/issue-69396-const-no-type-in-macro.stderr
View File

@ -17,10 +17,10 @@ LL | | }
= note: this error originates in the macro `suite` (in Nightly builds, run with -Z macro-backtrace for more info)
error: missing type for `const` item
--> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
--> $DIR/issue-69396-const-no-type-in-macro.rs:4:20
|
LL | const A = "A".$fn();
| ^ help: provide a type for the constant: `A: usize`
| ^ help: provide a type for the constant: `: usize`
...
LL | / suite! {
LL | | len;
@ -31,13 +31,13 @@ LL | | }
= note: this error originates in the macro `suite` (in Nightly builds, run with -Z macro-backtrace for more info)
error[E0121]: the placeholder `_` is not allowed within types on item signatures for constants
--> $DIR/issue-69396-const-no-type-in-macro.rs:4:19
--> $DIR/issue-69396-const-no-type-in-macro.rs:4:20
|
LL | const A = "A".$fn();
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `bool`
| ^
| |
| not allowed in type signatures
| help: replace with the correct type: `bool`
...
LL | / suite! {
LL | | len;

4
src/test/ui/parser/issues/issue-89574.stderr
View File

@ -1,8 +1,8 @@
error: missing type for `const` item
--> $DIR/issue-89574.rs:2:11
--> $DIR/issue-89574.rs:2:22
|
LL | const EMPTY_ARRAY = [];
| ^^^^^^^^^^^ help: provide a type for the item: `EMPTY_ARRAY: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to previous error

4
src/test/ui/parser/item-free-const-no-body-semantic-fail.stderr
View File

@ -15,10 +15,10 @@ LL | const B;
| help: provide a definition for the constant: `= <expr>;`
error: missing type for `const` item
--> $DIR/item-free-const-no-body-semantic-fail.rs:6:7
--> $DIR/item-free-const-no-body-semantic-fail.rs:6:8
|
LL | const B;
| ^ help: provide a type for the item: `B: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 3 previous errors

8
src/test/ui/parser/item-free-static-no-body-semantic-fail.stderr
View File

@ -31,16 +31,16 @@ LL | static mut D;
| help: provide a definition for the static: `= <expr>;`
error: missing type for `static` item
--> $DIR/item-free-static-no-body-semantic-fail.rs:6:8
--> $DIR/item-free-static-no-body-semantic-fail.rs:6:9
|
LL | static B;
| ^ help: provide a type for the item: `B: <type>`
| ^ help: provide a type for the item: `: <type>`
error: missing type for `static mut` item
--> $DIR/item-free-static-no-body-semantic-fail.rs:10:12
--> $DIR/item-free-static-no-body-semantic-fail.rs:10:13
|
LL | static mut D;
| ^ help: provide a type for the item: `D: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 6 previous errors

4
src/test/ui/parser/removed-syntax-static-fn.stderr
View File

@ -16,10 +16,10 @@ LL | }
| - the item list ends here
error: missing type for `static` item
--> $DIR/removed-syntax-static-fn.rs:4:12
--> $DIR/removed-syntax-static-fn.rs:4:14
|
LL | static fn f() {}
| ^^ help: provide a type for the item: `r#fn: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 3 previous errors

14
src/test/ui/suggestions/const-no-type.rs
View File

@ -14,38 +14,38 @@ fn main() {}
const C2 = 42;
//~^ ERROR missing type for `const` item
//~| HELP provide a type for the item
//~| SUGGESTION C2: <type>
//~| SUGGESTION : <type>
#[cfg(FALSE)]
static S2 = "abc";
//~^ ERROR missing type for `static` item
//~| HELP provide a type for the item
//~| SUGGESTION S2: <type>
//~| SUGGESTION : <type>
#[cfg(FALSE)]
static mut SM2 = "abc";
//~^ ERROR missing type for `static mut` item
//~| HELP provide a type for the item
//~| SUGGESTION SM2: <type>
//~| SUGGESTION : <type>
// These will, so the diagnostics should be stolen by typeck:
const C = 42;
//~^ ERROR missing type for `const` item
//~| HELP provide a type for the constant
//~| SUGGESTION C: i32
//~| SUGGESTION : i32
const D = &&42;
//~^ ERROR missing type for `const` item
//~| HELP provide a type for the constant
//~| SUGGESTION D: &&i32
//~| SUGGESTION : &&i32
static S = Vec::<String>::new();
//~^ ERROR missing type for `static` item
//~| HELP provide a type for the static variable
//~| SUGGESTION S: Vec<String>
//~| SUGGESTION : Vec<String>
static mut SM = "abc";
//~^ ERROR missing type for `static mut` item
//~| HELP provide a type for the static variable
//~| SUGGESTION &str
//~| SUGGESTION : &str

28
src/test/ui/suggestions/const-no-type.stderr
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@ -1,44 +1,44 @@
error: missing type for `const` item
--> $DIR/const-no-type.rs:33:7
--> $DIR/const-no-type.rs:33:8
|
LL | const C = 42;
| ^ help: provide a type for the constant: `C: i32`
| ^ help: provide a type for the constant: `: i32`
error: missing type for `const` item
--> $DIR/const-no-type.rs:38:7
--> $DIR/const-no-type.rs:38:8
|
LL | const D = &&42;
| ^ help: provide a type for the constant: `D: &&i32`
| ^ help: provide a type for the constant: `: &&i32`
error: missing type for `static` item
--> $DIR/const-no-type.rs:43:8
--> $DIR/const-no-type.rs:43:9
|
LL | static S = Vec::<String>::new();
| ^ help: provide a type for the static variable: `S: Vec<String>`
| ^ help: provide a type for the static variable: `: Vec<String>`
error: missing type for `static mut` item
--> $DIR/const-no-type.rs:48:12
--> $DIR/const-no-type.rs:48:14
|
LL | static mut SM = "abc";
| ^^ help: provide a type for the static variable: `SM: &str`
| ^ help: provide a type for the static variable: `: &str`
error: missing type for `const` item
--> $DIR/const-no-type.rs:14:7
--> $DIR/const-no-type.rs:14:9
|
LL | const C2 = 42;
| ^^ help: provide a type for the item: `C2: <type>`
| ^ help: provide a type for the item: `: <type>`
error: missing type for `static` item
--> $DIR/const-no-type.rs:20:8
--> $DIR/const-no-type.rs:20:10
|
LL | static S2 = "abc";
| ^^ help: provide a type for the item: `S2: <type>`
| ^ help: provide a type for the item: `: <type>`
error: missing type for `static mut` item
--> $DIR/const-no-type.rs:26:12
--> $DIR/const-no-type.rs:26:15
|
LL | static mut SM2 = "abc";
| ^^^ help: provide a type for the item: `SM2: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 7 previous errors

20
src/test/ui/suggestions/unnamable-types.stderr
View File

@ -1,8 +1,8 @@
error: missing type for `const` item
--> $DIR/unnamable-types.rs:6:7
--> $DIR/unnamable-types.rs:6:8
|
LL | const A = 5;
| ^ help: provide a type for the constant: `A: i32`
| ^ help: provide a type for the constant: `: i32`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/unnamable-types.rs:10:11
@ -26,10 +26,10 @@ LL | const C: _ = || 42;
| ^^^^^
error: missing type for `const` item
--> $DIR/unnamable-types.rs:23:7
--> $DIR/unnamable-types.rs:23:8
|
LL | const D = S { t: { let i = 0; move || -> i32 { i } } };
| ^
| ^
|
note: however, the inferred type `S<[closure@$DIR/unnamable-types.rs:23:31: 23:45]>` cannot be named
--> $DIR/unnamable-types.rs:23:11
@ -38,22 +38,22 @@ LL | const D = S { t: { let i = 0; move || -> i32 { i } } };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: missing type for `const` item
--> $DIR/unnamable-types.rs:29:7
--> $DIR/unnamable-types.rs:29:8
|
LL | const E = foo;
| ^ help: provide a type for the constant: `E: fn() -> i32`
| ^ help: provide a type for the constant: `: fn() -> i32`
error: missing type for `const` item
--> $DIR/unnamable-types.rs:32:7
--> $DIR/unnamable-types.rs:32:8
|
LL | const F = S { t: foo };
| ^ help: provide a type for the constant: `F: S<fn() -> i32>`
| ^ help: provide a type for the constant: `: S<fn() -> i32>`
error: missing type for `const` item
--> $DIR/unnamable-types.rs:37:7
--> $DIR/unnamable-types.rs:37:8
|
LL | const G = || -> i32 { yield 0; return 1; };
| ^
| ^
|
note: however, the inferred type `[generator@$DIR/unnamable-types.rs:37:11: 37:20]` cannot be named
--> $DIR/unnamable-types.rs:37:11

9
src/test/ui/typeck/issue-100164.fixed Normal file
View File

@ -0,0 +1,9 @@
// run-rustfix
const _A: i32 = 123;
//~^ ERROR: missing type for `const` item
fn main() {
const _B: i32 = 123;
//~^ ERROR: missing type for `const` item
}

9
src/test/ui/typeck/issue-100164.rs Normal file
View File

@ -0,0 +1,9 @@
// run-rustfix
const _A: = 123;
//~^ ERROR: missing type for `const` item
fn main() {
const _B: = 123;
//~^ ERROR: missing type for `const` item
}

14
src/test/ui/typeck/issue-100164.stderr Normal file
View File

@ -0,0 +1,14 @@
error: missing type for `const` item
--> $DIR/issue-100164.rs:3:10
|
LL | const _A: = 123;
| ^ help: provide a type for the constant: `i32`
error: missing type for `const` item
--> $DIR/issue-100164.rs:7:14
|
LL | const _B: = 123;
| ^ help: provide a type for the constant: `i32`
error: aborting due to 2 previous errors

4
src/test/ui/typeck/issue-79040.stderr
View File

@ -7,10 +7,10 @@ LL | const FOO = "hello" + 1;
| &str
error: missing type for `const` item
--> $DIR/issue-79040.rs:2:11
--> $DIR/issue-79040.rs:2:14
|
LL | const FOO = "hello" + 1;
| ^^^ help: provide a type for the item: `FOO: <type>`
| ^ help: provide a type for the item: `: <type>`
error: aborting due to 2 previous errors

4
src/test/ui/typeck/typeck_type_placeholder_item.stderr
View File

@ -189,10 +189,10 @@ LL ~ b: (T, T),
|
error: missing type for `static` item
--> $DIR/typeck_type_placeholder_item.rs:73:12
--> $DIR/typeck_type_placeholder_item.rs:73:13
|
LL | static A = 42;
| ^ help: provide a type for the static variable: `A: i32`
| ^ help: provide a type for the static variable: `: i32`
error[E0121]: the placeholder `_` is not allowed within types on item signatures for static variables
--> $DIR/typeck_type_placeholder_item.rs:75:15