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Rollup merge of #53183 - estebank:println-comma, r=oli-obk

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Suggest comma when missing in macro call

When missing a comma in a macro call, suggest it, regardless of
position. When a macro call doesn't match any of the patterns, check
if the call's token stream could be missing a comma between two idents,
and if so, create a new token stream containing the comma and try to
match against the macro patterns. If successful, emit the suggestion.

This works on arbitrary macros, with no need of special support from
the macro writers.

```
error: no rules expected the token `d`
  --> $DIR/missing-comma.rs:26:18
   |
LL |     foo!(a, b, c d, e);
   |                 -^
   |                 |
   |                 help: missing comma here
```
Follow up to #52397.
This commit is contained in:
kennytm 2018-08-09 16:58:49 +08:00
commit 8188f12aaa
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4 changed files with 73 additions and 19 deletions
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12
src/test/ui/macros/missing-comma.rs
View file

@ -9,7 +9,11 @@
// except according to those terms.
macro_rules! foo {
($a:ident, $b:ident) => ()
($a:ident) => ();
($a:ident, $b:ident) => ();
($a:ident, $b:ident, $c:ident) => ();
($a:ident, $b:ident, $c:ident, $d:ident) => ();
($a:ident, $b:ident, $c:ident, $d:ident, $e:ident) => ();
}
fn main() {
@ -17,4 +21,10 @@ fn main() {
//~^ ERROR expected token: `,`
foo!(a b);
//~^ ERROR no rules expected the token `b`
foo!(a, b, c, d e);
//~^ ERROR no rules expected the token `e`
foo!(a, b, c d, e);
//~^ ERROR no rules expected the token `d`
foo!(a, b, c d e);
//~^ ERROR no rules expected the token `d`
}

28
src/test/ui/macros/missing-comma.stderr
View file

@ -1,16 +1,38 @@
error: expected token: `,`
--> $DIR/missing-comma.rs:16:19
--> $DIR/missing-comma.rs:20:19
|
LL | println!("{}" a);
| ^
error: no rules expected the token `b`
--> $DIR/missing-comma.rs:18:12
--> $DIR/missing-comma.rs:22:12
|
LL | foo!(a b);
| -^
| |
| help: missing comma here
error: aborting due to 2 previous errors
error: no rules expected the token `e`
--> $DIR/missing-comma.rs:24:21
|
LL | foo!(a, b, c, d e);
| -^
| |
| help: missing comma here
error: no rules expected the token `d`
--> $DIR/missing-comma.rs:26:18
|
LL | foo!(a, b, c d, e);
| -^
| |
| help: missing comma here
error: no rules expected the token `d`
--> $DIR/missing-comma.rs:28:18
|
LL | foo!(a, b, c d e);
| ^
error: aborting due to 5 previous errors