Summary

When an Elixir def has a when guard, the generic AST translation falls back to a raw Call("def", ...) instead of producing a DefStmt/FuncDef node. Clauses without guards are correctly translated.

Reproduction

defmodule Fibonacci do
  def fib(0) do
    0
  end

  def fib(1) do
    1
  end

  def fib(n) when n > 1 do
    fib(n - 1) + fib(n - 2)
  end
end

opengrep-core -lang elixir -dump_ast fibonacci.ex

Observed AST (simplified)

ModuleDef("Fibonacci",
  ModuleStruct([
    DefStmt("fib", FuncDef(params=[OtherParam(0)], body=0)),        # OK
    DefStmt("fib", FuncDef(params=[OtherParam(1)], body=1)),        # OK
    ExprStmt(Call("def", [When(fib(n), n > 1), ArgKwd("do", ...)]))  # wrong
  ]))

Clauses 1 and 2 (no guard) are properly translated to DefStmt/FuncDef. Clause 3 (with when guard) is left as a raw Call("def", ...) with the guard buried inside OtherExpr("When", ...).

Expected behaviour

All three clauses should produce DefStmt/FuncDef nodes regardless of whether a when guard is present. The guard should be represented within the FuncDef structure (e.g. as a precondition or conditional in the body).

Note

Guards on fn lambdas already work correctly for taint analysis — see tests/tainting_rules/elixir/taint-lambda.ex line 41 (fn x when sink(x) -> x end). The issue is specific to def/defp with guards.