Confusing error message: "can't qualify macro invocation with pub" when a inherent method lacks "fn"

[ExpHP]

Both stable 1.14 and nightly 2017-01-06.
playpen

struct A {}

impl A {
    pub get(self) {}
}

(Edit: Above example is fixed as of 1.20.0, but free functions are affected.)

rustc 1.14.0 (e8a012324 2016-12-16)
error: can't qualify macro invocation with `pub`
 --> <anon>:4:5
  |
4 |     pub get(self) {}
  |     ^^^
  |
  = help: try adjusting the macro to put `pub` inside the invocation

error: expected one of `!` or `::`, found `(`
 --> <anon>:4:12
  |
4 |     pub get(self) {}
  |            ^

error: aborting due to previous error

while the actual issue is that the definition of get is missing the fn keyword.

[estebank]

If parse_impl_method doesn't see fn it tries to parse as macro, always and it uses complain_if_pub_macro to output the "can't qualify macro invocation with 'pub'" error. We can use the same approach as #42578 if we fail to find the !, rewind the parser and try to parse the rest as a method. If it succeeds in doing so, expand the diagnostic with a suggestion to write pub fn get, otherwise rewind the parser to the previous error and emit the original diagnostic without modification.

[ExpHP]

On the contrary, it seems to me this has been fixed: (current playpen, presumably 1.20.0)

error: missing `fn`, `type`, or `const` for impl-item declaration
 --> src/main.rs:4:8
  |
4 |     pub get(self) {}
  |        ^ missing `fn`, `type`, or `const`

error: aborting due to previous error

[ExpHP]

Ahah, it still occurs for functions that are not part of an impl.

pub get(x: u8) {}

fn main() {}

   Compiling playground v0.0.1 (file:///playground)
error: can't qualify macro invocation with `pub`
 --> src/main.rs:1:1
  |
1 | pub get(x: u8) {}
  | ^^^
  |
  = help: try adjusting the macro to put `pub` inside the invocation

error: expected one of `!` or `::`, found `(`
 --> src/main.rs:1:8
  |
1 | pub get(x: u8) {}
  |        ^ expected one of `!` or `::` here

error: aborting due to 2 previous errors

error: Could not compile `playground`.

---

@estebank 's analysis seems to suggest that impl methods should still have issues though. I wonder if there is another example where an impl method still produces the old error?

[fschutt]

Just wanted to say, this happens when you create a struct but forget the struct keyword:

pub MyStruct { }; // keyword struct missing

fn main() { }

   Compiling playground v0.0.1 (file:///playground)
error: can't qualify macro invocation with `pub`
 --> src/main.rs:1:1
  |
1 | pub MyStruct { }; // keyword struct missing
  | ^^^
  |
  = help: try adjusting the macro to put `pub` inside the invocation

error: expected one of `!` or `::`, found `{`
 --> src/main.rs:1:14
  |
1 | pub MyStruct { }; // keyword struct missing
  |             -^ unexpected token
  |             |
  |             expected one of `!` or `::` here

error: aborting due to 2 previous errors

A better error message would be helpful.