E0050 emitted unexpectedly on missing :

[lolbinarycat]

Code

use std::fmt;

struct Hello;

impl fmt::Display for Hello {
    fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
        write!(f, "hello")
    }
}

Current output

Compiling playground v0.0.1 (/playground)
error: expected parameter name, found `:`
 --> src/lib.rs:6:26
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                          ^ expected parameter name

error: expected one of `!`, `(`, `)`, `,`, `::`, or `<`, found `:`
 --> src/lib.rs:6:26
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                          ^
  |                          |
  |                          expected one of `!`, `(`, `)`, `,`, `::`, or `<`
  |                          help: missing `,`

error[E0573]: expected type, found module `fmt`
 --> src/lib.rs:6:23
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                       ^^^ not a type

error[E0050]: method `fmt` has 3 parameters but the declaration in trait `std::fmt::Display::fmt` has 2
 --> src/lib.rs:6:12
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |            ^^^^^^^^^^^^^^^^^^^^^^^^ expected 2 parameters, found 3
  |
  = note: `fmt` from trait: `fn(&Self, &mut Formatter<'_>) -> Result<(), std::fmt::Error>`

Some errors have detailed explanations: E0050, E0573.
For more information about an error, try `rustc --explain E0050`.
error: could not compile `playground` (lib) due to 4 previous errors

Desired output

Compiling playground v0.0.1 (/playground)
error: expected parameter name, found `:`
 --> src/lib.rs:6:26
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                          ^ expected parameter name

error: expected one of `!`, `(`, `)`, `,`, `::`, or `<`, found `:`
 --> src/lib.rs:6:26
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                          ^
  |                          |
  |                          expected one of `!`, `(`, `)`, `,`, `::`, or `<`
  |                          help: missing `,`

error[E0573]: expected type, found module `fmt`
 --> src/lib.rs:6:23
  |
6 |     fn fmt(&self, f: &fmt:Formatter) -> fmt::Result {
  |                       ^^^ not a type

Some errors have detailed explanations: E0050, E0573.
For more information about an error, try `rustc --explain E0050`.
error: could not compile `playground` (lib) due to 4 previous errors

Rationale and extra context

When looking at rust-analyzer output or when just looking at the last few error messages, it's easy to see only the "too many arguments" error, and not the syntax error that points at the exact problem.

Other cases

No response

Rust Version

1.80.1

Anything else?

No response

[jieyouxu]

Reopening this issue due to revert #140228 to address #140227.