Using 0..=usize::MAX as the definition scope allows the function to be referenced from anywhere in the file, including before its definition. This enables recursion but also permits forward references that may be unintended.

Consider using name_span.start..=usize::MAX instead, which would make the function visible from the point of its declaration forward (including within its own body for recursion) while preventing forward references from earlier in the file. This would be more consistent with typical scoping rules.

Potential index out of bounds error when accessing new_generic_types[idx]. The variable idx represents the position in the args array, but new_generic_types only contains entries for generic and optional arguments without explicit types.

For example, with fun foo(a: Num, b), args has 2 elements but new_generic_types has only 1. When processing argument at index 0 (a: Num), the code would try to access new_generic_types[0] in the Typed branch (line 236), which doesn't make sense since typed arguments don't add to new_generic_types. When processing argument at index 1 (b), it would try new_generic_types[1] which is out of bounds.

The old code used new_generic_types.remove(0) which correctly dequeued generics in order. Consider maintaining a separate counter for generic indices or reverting to the dequeue approach.

The comment "When both operands are unknown generics, they should get the broad constraint" appears to be copy-pasted from another test and is not relevant to this recursion test. The ackermann function uses typed parameters (m: Num, n: Num) and doesn't involve generic constraints. Consider updating the comment to describe what this test is actually verifying (e.g., "Test that recursive function calls are properly analyzed and symbol table is correctly populated").