Compiling a function returning an unknown numeric generic panics

[michaeljklein]

Aim

Attempted to compile the following program with a function that outputs a numeric generic:

// Using "[(); N]" as a parameter compiles and executes successfully
//
// Using "struct W<N> {}" as a parameter also panics if "foo" is called on "W {}",
// but not if "foo" is called on "let w_1: W<1> = W {};"
fn foo<let N: u32>() -> u32 {
    N
}

fn main() {
    foo();
}

Expected Behavior

The program to compile successfully or fail with a user error

Bug

Compiling the program panics with the following message:

The application panicked (crashed).
Message:  Non-numeric type variable used in expression expecting a value
Location: compiler/noirc_frontend/src/monomorphization/mod.rs:934

To Reproduce

Workaround

Yes

Workaround Description

Use turbofish (e.g. foo::<3>()) to specify numeric generics when they can't be derived from a parameter's type

Additional Context

No response

Project Impact

None

Blocker Context

No response

Nargo Version

nargo version = 0.36.0 noirc version = 0.36.0+2f376100d3ee7ab519d6ea30153395bb3e7af7b1 (git version hash: 2f37610, is dirty: false)

NoirJS Version

No response

Proving Backend Tooling & Version

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response

[michaeljklein]

Could be related to #6126

[jfecher]

Hmm I had thought we had a check for this case already but it looks like what was added was a slightly different check: #5840. I would've still expected main to error that the generic in the call to foo wasn't known however.

Maybe we need to edit the check_type method that is called to be more stringent.