[wgsl-in] Confusing error: "expected unsigned/signed integer literal, found '1'"

[kpreid]

I'm not familiar with the WGSL specification and couldn't figure it out quickly, so I'm not sure if this is a validation error or merely a poor error message. Given that it used to be accepted, I'm guessing the latter.

The following passes validation with naga 0.8.5 (current crates.io release) but fails on git (as of commit 27d38aa)

fn switcher(input: u32) {
    switch (input) {
        case 1: {}
        default: {}
    }
}

error: expected unsigned/signed integer literal, found '1'
  ┌─ test.wgsl:3:14
  │
3 │         case 1: {}
  │              ^ expected unsigned/signed integer literal

The error goes away if I change 1 to 1u, making it explicitly unsigned. If this program should pass validation, then the message is quite confusing: it doesn't specify that I need an unsigned integer, and it doesn't make it clear that this is a type mismatch and not a syntax error.

[teoxoy]

This seems to be a side-effect of #1863.

The tokenizer now differentiates between concrete types (those with suffixes) and abstract ones.

The plan is to infer the type of abstract numbers as per spec (improving the errors in the process).

[teoxoy]

Track gfx-rs/wgpu#4400 for automatic type conversions.