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Rollup merge of #84793 - estebank:parse-struct-field-default, r=davidtwco

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Recover from invalid `struct` item syntax

Parse unsupported "default field const values":

```rust
struct S {
    field: Type = const_val,
}
```

Recover from small `:` typo and provide suggestion:

```rust
struct S {
    field; Type,
    field2= Type,
}
```
This commit is contained in:
Guillaume Gomez 2021-05-12 17:19:25 +02:00 committed by GitHub
commit 94617802a1
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 207 additions and 1 deletions
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46
compiler/rustc_parse/src/parser/item.rs
View File

@ -1399,6 +1399,37 @@ impl<'a> Parser<'a> {
Ok(a_var)
}
fn expect_field_ty_separator(&mut self) -> PResult<'a, ()> {
if let Err(mut err) = self.expect(&token::Colon) {
let sm = self.sess.source_map();
let eq_typo = self.token.kind == token::Eq && self.look_ahead(1, |t| t.is_path_start());
let semi_typo = self.token.kind == token::Semi
&& self.look_ahead(1, |t| {
t.is_path_start()
// We check that we are in a situation like `foo; bar` to avoid bad suggestions
// when there's no type and `;` was used instead of a comma.
&& match (sm.lookup_line(self.token.span.hi()), sm.lookup_line(t.span.lo())) {
(Ok(l), Ok(r)) => l.line == r.line,
_ => true,
}
});
if eq_typo || semi_typo {
self.bump();
// Gracefully handle small typos.
err.span_suggestion_short(
self.prev_token.span,
"field names and their types are separated with `:`",
":".to_string(),
Applicability::MachineApplicable,
);
err.emit();
} else {
return Err(err);
}
}
Ok(())
}
/// Parses a structure field.
fn parse_name_and_ty(
&mut self,
@ -1408,8 +1439,21 @@ impl<'a> Parser<'a> {
attrs: Vec<Attribute>,
) -> PResult<'a, FieldDef> {
let name = self.parse_field_ident(adt_ty, lo)?;
self.expect(&token::Colon)?;
self.expect_field_ty_separator()?;
let ty = self.parse_ty()?;
if self.token.kind == token::Eq {
self.bump();
let const_expr = self.parse_anon_const_expr()?;
let sp = ty.span.shrink_to_hi().to(const_expr.value.span);
self.struct_span_err(sp, "default values on `struct` fields aren't supported")
.span_suggestion(
sp,
"remove this unsupported default value",
String::new(),
Applicability::MachineApplicable,
)
.emit();
}
Ok(FieldDef {
span: lo.to(self.prev_token.span),
ident: Some(name),

35
src/test/ui/parser/struct-default-values-and-missing-field-separator.fixed Normal file
View File

@ -0,0 +1,35 @@
// run-rustfix
#![allow(dead_code)]
enum E {
A,
}
struct S {
field1: i32, //~ ERROR default values on `struct` fields aren't supported
field2: E, //~ ERROR default values on `struct` fields aren't supported
field3: i32, //~ ERROR default values on `struct` fields aren't supported
field4: i32, //~ ERROR default values on `struct` fields aren't supported
field5: E, //~ ERROR default values on `struct` fields aren't supported
field6: E, //~ ERROR default values on `struct` fields aren't supported
}
struct S1 {
field1: i32, //~ ERROR expected `,`, or `}`, found `field2`
field2: E, //~ ERROR expected `,`, or `}`, found `field3`
field3: i32, //~ ERROR default values on `struct` fields aren't supported
field4: i32, //~ ERROR default values on `struct` fields aren't supported
field5: E, //~ ERROR default values on `struct` fields aren't supported
field6: E, //~ ERROR default values on `struct` fields aren't supported
}
struct S2 {
field1 : i32, //~ ERROR expected `:`, found `=`
field2: E, //~ ERROR expected `:`, found `;`
}
const fn foo(_: i32) -> E {
E::A
}
fn main() {}

35
src/test/ui/parser/struct-default-values-and-missing-field-separator.rs Normal file
View File

@ -0,0 +1,35 @@
// run-rustfix
#![allow(dead_code)]
enum E {
A,
}
struct S {
field1: i32 = 42, //~ ERROR default values on `struct` fields aren't supported
field2: E = E::A, //~ ERROR default values on `struct` fields aren't supported
field3: i32 = 1 + 2, //~ ERROR default values on `struct` fields aren't supported
field4: i32 = { 1 + 2 }, //~ ERROR default values on `struct` fields aren't supported
field5: E = foo(42), //~ ERROR default values on `struct` fields aren't supported
field6: E = { foo(42) }, //~ ERROR default values on `struct` fields aren't supported
}
struct S1 {
field1: i32 //~ ERROR expected `,`, or `}`, found `field2`
field2: E //~ ERROR expected `,`, or `}`, found `field3`
field3: i32 = 1 + 2, //~ ERROR default values on `struct` fields aren't supported
field4: i32 = { 1 + 2 }, //~ ERROR default values on `struct` fields aren't supported
field5: E = foo(42), //~ ERROR default values on `struct` fields aren't supported
field6: E = { foo(42) }, //~ ERROR default values on `struct` fields aren't supported
}
struct S2 {
field1 = i32, //~ ERROR expected `:`, found `=`
field2; E, //~ ERROR expected `:`, found `;`
}
const fn foo(_: i32) -> E {
E::A
}
fn main() {}

92
src/test/ui/parser/struct-default-values-and-missing-field-separator.stderr Normal file
View File

@ -0,0 +1,92 @@
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:9:16
|
LL | field1: i32 = 42,
| ^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:10:14
|
LL | field2: E = E::A,
| ^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:11:16
|
LL | field3: i32 = 1 + 2,
| ^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:12:16
|
LL | field4: i32 = { 1 + 2 },
| ^^^^^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:13:14
|
LL | field5: E = foo(42),
| ^^^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:14:14
|
LL | field6: E = { foo(42) },
| ^^^^^^^^^^^^^^ help: remove this unsupported default value
error: expected `,`, or `}`, found `field2`
--> $DIR/struct-default-values-and-missing-field-separator.rs:18:16
|
LL | field1: i32
| ^ help: try adding a comma: `,`
error: expected `,`, or `}`, found `field3`
--> $DIR/struct-default-values-and-missing-field-separator.rs:19:14
|
LL | field2: E
| ^ help: try adding a comma: `,`
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:20:16
|
LL | field3: i32 = 1 + 2,
| ^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:21:16
|
LL | field4: i32 = { 1 + 2 },
| ^^^^^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:22:14
|
LL | field5: E = foo(42),
| ^^^^^^^^^^ help: remove this unsupported default value
error: default values on `struct` fields aren't supported
--> $DIR/struct-default-values-and-missing-field-separator.rs:23:14
|
LL | field6: E = { foo(42) },
| ^^^^^^^^^^^^^^ help: remove this unsupported default value
error: expected `:`, found `=`
--> $DIR/struct-default-values-and-missing-field-separator.rs:27:12
|
LL | field1 = i32,
| ^
| |
| expected `:`
| help: field names and their types are separated with `:`
error: expected `:`, found `;`
--> $DIR/struct-default-values-and-missing-field-separator.rs:28:11
|
LL | field2; E,
| ^
| |
| expected `:`
| help: field names and their types are separated with `:`
error: aborting due to 14 previous errors