[DSLX] can't use parametric constexprs in struct definition

[dank-openai]

Describe the bug

I'm unable to do something with parametrics; I think it should be legal. As best as I can tell, the narrowest definition of the bug is: I can't use constexprs in a struct's parametric definitions.

To Reproduce

pub struct FixedPoint<SIGNED:u32, NUM_BITS: u32,  SIGNED_BOOL: bool = {SIGNED > u32:0} > {
    data: xN[SIGNED_BOOL][NUM_BITS],
}

#[test]
fn test_instantiate_FixedPoint() {
    let a = FixedPoint<u32:0, u32:5> { data: u5:1};
    assert_eq(a.data, u5:1);
}

Build and test the above. The error shows up during the test.

Error: INVALID_ARGUMENT: Cannot convert expression to parametric: SIGNED > u32:0================================================================================

Expected behavior
It should work, the test should pass.

Additional context

If you're wondering why I made SIGNED a u32 instead of bool, see this bug.

I find it strange that this error appears at test runtime instead of typechecking.