Extra whitespace inserted between literal and line comment.

When inserting line comments in an array literal, rustfmt sometimes insert unnecessary empty space.

Simplest example:

let example_correct = [
    0, 0, // comment 1
    0, // comment 2
];

let example_incorrect = [
    0, 0x0, // comment 1
    0,   // comment 2
];

Notice how there are three spaces between the trailing comma and the comment 2 in the incorrect example.

Examples can be reproduced on the Rust Playground, which uses rustfmt 1.6.0-nighty (2023-07-10 8ca44ef), as well as with rust-analyzer v0.3.1583 VS Code extension.

Reproduce the issue with the array-literal examples in the report using rustfmt or the Rust Playground. Compare formatting around the trailing comma and line comment, then trace the formatter behavior responsible for comment spacing. Done means the incorrect example no longer gains extra whitespace while the existing formatting remains unchanged.