gh-74929: Implement PEP 667

Include/cpython/frameobject.h

@@ -27,3 +27,9 @@ PyAPI_FUNC(int) _PyFrame_IsEntryFrame(PyFrameObject *frame);
 
 PyAPI_FUNC(int) PyFrame_FastToLocalsWithError(PyFrameObject *f);
 PyAPI_FUNC(void) PyFrame_FastToLocals(PyFrameObject *);
+
+
+typedef struct {
+    PyObject_HEAD
+    PyFrameObject* frame;
+} PyFrameLocalsProxyObject;

Include/cpython/pyframe.h

@@ -3,8 +3,10 @@
 #endif
 
 PyAPI_DATA(PyTypeObject) PyFrame_Type;
+PyAPI_DATA(PyTypeObject) PyFrameLocalsProxy_Type;
 
 #define PyFrame_Check(op) Py_IS_TYPE((op), &PyFrame_Type)
+#define PyFrameLocalsProxy_Check(op) Py_IS_TYPE((op), &PyFrameLocalsProxy_Type)
 
 PyAPI_FUNC(PyFrameObject *) PyFrame_GetBack(PyFrameObject *frame);
 PyAPI_FUNC(PyObject *) PyFrame_GetLocals(PyFrameObject *frame);

Include/internal/pycore_frame.h

@@ -61,6 +61,7 @@ typedef struct _PyInterpreterFrame {
     PyObject *f_globals; /* Borrowed reference. Only valid if not on C stack */
     PyObject *f_builtins; /* Borrowed reference. Only valid if not on C stack */
     PyObject *f_locals; /* Strong reference, may be NULL. Only valid if not on C stack */
+    PyObject *f_extra_locals; /* Strong reference, may be NULL. Only valid if not on C stack */
     PyFrameObject *frame_obj; /* Strong reference, may be NULL. Only valid if not on C stack */
     _Py_CODEUNIT *instr_ptr; /* Instruction currently executing (or about to begin) */
     int stacktop;  /* Offset of TOS from localsplus  */
@@ -126,6 +127,7 @@ _PyFrame_Initialize(
     frame->f_builtins = func->func_builtins;
     frame->f_globals = func->func_globals;
     frame->f_locals = locals;
+    frame->f_extra_locals = PyDict_New();
     frame->stacktop = code->co_nlocalsplus;
     frame->frame_obj = NULL;
     frame->instr_ptr = _PyCode_CODE(code);
@@ -235,6 +237,9 @@ _PyFrame_Traverse(_PyInterpreterFrame *frame, visitproc visit, void *arg);
 PyObject *
 _PyFrame_GetLocals(_PyInterpreterFrame *frame, int include_hidden);
 
+PyObject *
+_PyFrame_GetHiddenLocals(_PyInterpreterFrame *frame);
+
 int
 _PyFrame_FastToLocalsWithError(_PyInterpreterFrame *frame);
 
@@ -289,6 +294,7 @@ _PyFrame_PushTrampolineUnchecked(PyThreadState *tstate, PyCodeObject *code, int
     frame->f_globals = NULL;
 #endif
     frame->f_locals = NULL;
+    frame->f_extra_locals = NULL;
     frame->stacktop = code->co_nlocalsplus + stackdepth;
     frame->frame_obj = NULL;
     frame->instr_ptr = _PyCode_CODE(code);