Credence.Rule.InconsistentParamNames (credence v0.2.0)

Detects functions where the same positional parameter uses different variable names across clauses.

Why this matters

LLMs generate function clauses semi-independently, often drifting parameter names between clauses of the same function:

# Flagged — first arg is "current" in one clause, "prev" in another
defp do_fibonacci(current, _next, 0), do: current
defp do_fibonacci(prev, current, steps), do: do_fibonacci(current, prev + current, steps - 1)

# Consistent — same name at each position across all clauses
defp do_fibonacci(prev, _current, 0), do: prev
defp do_fibonacci(prev, current, steps), do: do_fibonacci(current, prev + current, steps - 1)

Inconsistent names make the reader question whether the function is correct — if the first argument is called current in one clause and prev in another, which is it?

Detection scope (strict)

Only simple variables are compared. A position is skipped if any clause uses a pattern, literal, or underscore-prefixed variable at that position. This avoids false positives on legitimate pattern-matching dispatch like:

def handle({:ok, result}), do: result
def handle({:error, reason}), do: raise reason

Single-clause functions are never flagged.

Severity

:warning