Internal compiler error when reassigning a mutable lambda variable to one with a different environment type

[alexvitkov]

Aim

This code type-checks properly, but an assertion fails during SSA generation.
The reassignment is invalid since the two lambdas have different environment types, and should be caught during type-checking.

fn main() {
    let a: u32 = 1;
    let b: u32 = 1;

    let mut f = || a;
    f = || a + b;

    f();
}

Expected Behavior

We may want to support this behavior long term, but it's difficult since the lambdas are of different types, so for the time being I think we should throw a type error that the assignment is invalid.

Bug

The compiler crashes on the code above

To Reproduce

Compile the code above

Installation Method

Compiled from source

Nargo Version

nargo 0.9.0

Additional Context

No response

Would you like to submit a PR for this Issue?

Yes

Support Needs

No response

[jfecher]

We may want to support this behavior long term, but it's difficult since the lambdas are of different types, so for the time being I think we should throw a type error that the assignment is invalid.

I agree with this assessment, lets issue a type error now and we can look into allowing this later