Execute SET_FUNCTION_ATTRIBUTE before wrapping for #617

enaml/core/compiler_common.py

@@ -61,9 +61,6 @@
                    ast.DictComp,
                    ast.SetComp)
 
-#: Opcode used to create a function
-_MAKE_FUNC = ("MAKE_FUNCTION",)
-
 
 def unhandled_pragma(name, filename, lineno):
     """ Emit a warning for an unhandled pragma.
@@ -445,7 +442,11 @@ def run_in_dynamic_scope(code: bc.Bytecode, global_vars: set[str]) -> None:
     fetch_helpers(cg)
 
     # Scan all ops to detect function call after GET_ITER
-    for instr in instrs:
+    idx = 0
+    num_instrs = len(instrs)
+    while idx < num_instrs:
+        instr = instrs[idx]
+        idx += 1
         if not isinstance(instr, bc.Instr):
             cg.code_ops.append(instr)
             continue
@@ -462,8 +463,17 @@ def run_in_dynamic_scope(code: bc.Bytecode, global_vars: set[str]) -> None:
             run_in_dynamic_scope(inner, global_vars)
             inner.update_flags()
             i_arg = inner.to_code()
-        elif any(i_name == make_fun_op for make_fun_op in _MAKE_FUNC):
+        elif i_name == "MAKE_FUNCTION":
             cg.code_ops.append(bc.Instr(i_name, i_arg))  # func
+
+            if PY313 and idx < num_instrs:
+                # If the next instruction is SET_FUNCTION_ATTRIBUTE it needs
+                # executed before wrapping the function in order to setup defaults on the stack.
+                i_next = instrs[idx]
+                if isinstance(i_next, bc.Instr) and i_next.name == "SET_FUNCTION_ATTRIBUTE":
+                    cg.code_ops.append(bc.Instr(i_next.name, i_next.arg, location=instr.location))
+                    idx += 1 # Skip the instruction
+
             load_helper(cg, 'wrap_func')                 # func -> wrap
             cg.rot_two()                                 # wrap -> func
             # Python 3.11 and 3.12 requires a NULL before a function that is not a method

tests/core/test_compiler.py

@@ -61,3 +61,35 @@ class A:
 
 
 # XXX add test regarding handling of with statement
+
+
+def test_compile_lamba_with_default():
+    source = dedent("""\
+    from enaml.widgets.api import Window
+
+    enamldef Main(Window):
+        attr f = lambda v="x": v
+    """)
+    Main = compile_source(source, 'Main')
+    window = Main()
+    assert window.f() == "x"
+    assert window.f("y") == "y"
+
+
+def test_compile_lamba_with_default_in_dict_comp():
+    source = dedent("""\
+    from enaml.widgets.api import Window
+
+    enamldef Main(Window):
+        attr mode: str = "a"
+        attr keymap = {
+            k: lambda v=k: setattr(self, "mode", v)
+            for k in ("a", "b")
+        }
+    """)
+    Main = compile_source(source, 'Main')
+    window = Main()
+    assert window.mode == "a"
+    window.keymap['b']()
+    assert window.mode == "b"
+