macro: Allow the repetition of metavars when expanding repetitions

When expanding repeating metavars, we have to allow the repetition of non-repeating metavars as well:

```
macro_rules! foo {
    ( ( $( $Trait: ident ),+ ) for $Ty: ident ) => {
        $(
            impl $Trait for $Ty {
                fn bar() -> i32 {
                    14
                }
            }
        )+
    }
}

trait Foo {
    fn bar() -> i32;
}

trait Bar {
    fn bar() -> i32;
}

trait Baz {
    fn bar() -> i32;
}

trait Qux {
    fn bar() -> i32;
}

struct S;

foo!{(Foo, Bar, Baz, Qux) for S}
```

This is valid, as the $Ty metavar is not a repetition. However, this should fail to compile:

```
macro_rules! foo {
//                                 note the repetition here now
    ( ( $( $Trait: ident ),+ ) for $($Ty: ident)+ ) => {
        $(
            impl $Trait for $Ty {
                fn bar() -> i32 {
                    14
                }
            }
        )+
    }
}

trait Foo {
    fn bar() -> i32;
}

trait Bar {
    fn bar() -> i32;
}

trait Baz {
    fn bar() -> i32;
}

trait Qux {
    fn bar() -> i32;
}

struct S;

foo!{(Foo, Bar, Baz, Qux) for S}
```

Obviously, if we were to specify as many $Ty as $Trait then there would be no issue, but that behavior is already handled.

0 files changed, 0 insertions, 0 deletions