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Rollup merge of #102350 - TaKO8Ki:incomplete-fn-in-struct-definition, r=fee1-dead

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Improve errors for incomplete functions in struct definitions

Given the following code:

```rust
fn main() {}

struct Foo {
    fn
}
```

[playground](https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=29139f870511f6918324be5ddc26c345)

The current output is:

```
   Compiling playground v0.0.1 (/playground)
error: functions are not allowed in struct definitions
 --> src/main.rs:4:5
  |
4 |     fn
  |     ^^
  |
  = help: unlike in C++, Java, and C#, functions are declared in `impl` blocks
  = help: see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information

error: could not compile `playground` due to previous error
```

In this case, rustc should suggest escaping `fn` to use it as an identifier.
This commit is contained in:
Matthias Krüger 2022-09-30 10:22:37 +02:00 • committed by GitHub
commit 6906e64c30
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5 changed files with 44 additions and 16 deletions
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28
compiler/rustc_parse/src/parser/item.rs
View file

@ -1753,18 +1753,24 @@ impl<'a> Parser<'a> {
};
// We use `parse_fn` to get a span for the function
let fn_parse_mode = FnParseMode { req_name: |_| true, req_body: true };
if let Err(mut db) =
self.parse_fn(&mut AttrVec::new(), fn_parse_mode, lo, &inherited_vis)
{
db.delay_as_bug();
match self.parse_fn(&mut AttrVec::new(), fn_parse_mode, lo, &inherited_vis) {
Ok(_) => {
let mut err = self.struct_span_err(
lo.to(self.prev_token.span),
&format!("functions are not allowed in {adt_ty} definitions"),
);
err.help(
"unlike in C++, Java, and C#, functions are declared in `impl` blocks",
);
err.help("see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information");
err
}
Err(err) => {
err.cancel();
self.restore_snapshot(snapshot);
self.expected_ident_found()
}
}
let mut err = self.struct_span_err(
lo.to(self.prev_token.span),
&format!("functions are not allowed in {adt_ty} definitions"),
);
err.help("unlike in C++, Java, and C#, functions are declared in `impl` blocks");
err.help("see https://doc.rust-lang.org/book/ch05-03-method-syntax.html for more information");
err
} else if self.eat_keyword(kw::Struct) {
match self.parse_item_struct() {
Ok((ident, _)) => {