`>=` typo gives unclear error message

[macmv]

Given the following code:

let is_greater = 5 => 3;

The current output is:

   Compiling playground v0.0.1 (/playground)
error: expected one of `.`, `;`, `?`, `else`, or an operator, found `=>`
 --> src/main.rs:2:24
  |
2 |     let is_greater = 5 => 3;
  |                        ^^ expected one of `.`, `;`, `?`, `else`, or an operator

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

playground

This had me very confused for a surprising amount of time. It would be nice if the compiler would give a suggestion to replace => with >=. In my opinion, this would help a lot for someone typing quickly, and would make it clear that the symbols were in reverse. It might also lead to some false positives, but I think it would still be nice to have.

The error is actually worse for macros:

macro_rules! accept_expr {
    ( $expr:expr ) => { $expr }
}

fn main() {
    accept_expr!(5 => 3);
}

The current output for this macro is:

   Compiling playground v0.0.1 (/playground)
error: no rules expected the token `=>`
 --> src/main.rs:6:20
  |
1 | macro_rules! accept_expr {
  | ------------------------ when calling this macro
...
6 |     accept_expr!(5 => 3);
  |                    ^^ no rules expected this token in macro call

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

My suggestion it to simply add a help section to both of the above errors, which would suggest replacing the => token with >=.

[compiler-errors]

This is complicated, given that => is parsed as its own token as opposed the equivalent typo =< for the lt operator. I'm not confident that fixing this (at least in the macro_rules! case, but possibly in arbitrary positions) is possible, because this is a valid macro:

macro_rules! foo {
    ($a:expr => $b:expr) => {};
}

[ChayimFriedman2]

If this is possible, it would also be nice to mention closures there, since a => b is the closure syntax in many languages.

[veera-sivarajan]

Output on rustc 1.79.0:

error: expected one of `.`, `;`, `?`, `else`, or an operator, found `=>`
 --> <source>:3:24
  |
3 |     let is_greater = 5 => 3;
  |                        ^^ expected one of `.`, `;`, `?`, `else`, or an operator
  |
help: you might have meant to write a "greater than or equal to" comparison
  |
3 |     let is_greater = 5 >= 3;
  |                        ~~

error: aborting due to 1 previous error

[estebank]

As per the above, I consider this fixed. We already have extensive tests for this check.