Example usage of test_matrix broken

[till-metaco]

Description

The example usage for test_matrix does not compile in version 3.3.1 with rustc 1.77.2.

To reproduce

1. Create an empty project with cargo new test_matrix
2. Add test_case with cargo add --dev test-case
3. Add the test module from the example usage on crates.io like so

fn main() {
    println!("Hello, world!");
}

#[cfg(test)]
mod tests {
    use test_case::test_matrix;

    #[test_matrix(
        [-2, 2],
        [-4, 4]
    )]
    fn multiplication_matrix_tests(x: i8, y: i8) {
        let actual = (x * y).abs();

        assert_eq!(8, actual)
    }
}

4. Compile and run the tests with cargo test

Expected behaviour

The tests compile and run without errors

Actual behaviour

The tests don't compile with the error message

error[E0428]: the name `_2_2_expects` is defined multiple times
  --> src/main.rs:9:5
   |
9  | /     #[test_matrix(
10 | |         [-2, 2],
11 | |         [-2, 4]
12 | |     )]
   | |______^ `_2_2_expects` redefined here
   |
   = note: `_2_2_expects` must be defined only once in the value namespace of this module
   = note: this error originates in the attribute macro `test_matrix` (in Nightly builds, run with -Z macro-backtrace for more info)

Additional context

The error seems to stem from the way the minus signs are translated to function names, because it compiles if the matrix is defined as

   #[test_matrix(
        [-1, 2],
        [-3, 4]
    )]

(these tests compile, but fail for obvious reasons.

[till-metaco]

Seems related to #19