gh-108732: include comprehension locals in frame.f_locals (#109026)

Co-authored-by: Radislav Chugunov <52372310+chgnrdv@users.noreply.github.com>
Co-authored-by: Jelle Zijlstra <jelle.zijlstra@gmail.com>

Lib/test/test_listcomps.py

@@ -596,6 +596,13 @@ class ListComprehensionTest(unittest.TestCase):
         """
         self._check_in_scopes(code, {"value": [1, None]})
 
+    def test_frame_locals(self):
+        code = """
+            val = [sys._getframe().f_locals for a in [0]][0]["a"]
+        """
+        import sys
+        self._check_in_scopes(code, {"val": 0}, ns={"sys": sys})
+
 
 __test__ = {'doctests' : doctests}
 

Misc/NEWS.d/next/Core and Builtins/2023-09-06-13-28-42.gh-issue-108732.I6DkEQ.rst

@@ -0,0 +1,2 @@
+Make iteration variables of module- and class-scoped comprehensions visible
+to pdb and other tools that use ``frame.f_locals`` again.

Objects/frameobject.c

@@ -25,10 +25,16 @@ static PyMemberDef frame_memberlist[] = {
 static PyObject *
 frame_getlocals(PyFrameObject *f, void *closure)
 {
-    if (PyFrame_FastToLocalsWithError(f) < 0)
+    if (f == NULL) {
+        PyErr_BadInternalCall();
         return NULL;
-    PyObject *locals = f->f_frame->f_locals;
+    }
-    return Py_NewRef(locals);
+    assert(!_PyFrame_IsIncomplete(f->f_frame));
+    PyObject *locals = _PyFrame_GetLocals(f->f_frame, 1);
+    if (locals) {
+        f->f_fast_as_locals = 1;
+    }
+    return locals;
 }
 
 int
@@ -1342,11 +1348,11 @@ PyFrame_GetVarString(PyFrameObject *frame, const char *name)
 int
 PyFrame_FastToLocalsWithError(PyFrameObject *f)
 {
-    assert(!_PyFrame_IsIncomplete(f->f_frame));
     if (f == NULL) {
         PyErr_BadInternalCall();
         return -1;
     }
+    assert(!_PyFrame_IsIncomplete(f->f_frame));
     int err = _PyFrame_FastToLocalsWithError(f->f_frame);
     if (err == 0) {
         f->f_fast_as_locals = 1;