Make func.__doc__ a property that defers to func.__code__.co_doc

gvanrossum · gvanrossum · commit 1e1bc778c3d5 · 2021-07-19T17:31:54.000-07:00
(Unless set explicitly)
diff --git a/Objects/funcobject.c b/Objects/funcobject.c
@@ -3,6 +3,7 @@
 
 #include "Python.h"
 #include "pycore_ceval.h"         // _PyEval_BuiltinsFromGlobals()
+#include "pycore_code.h"          // Hydration
 #include "pycore_object.h"        // _PyObject_GC_UNTRACK()
 #include "pycore_pyerrors.h"      // _PyErr_Occurred()
 #include "structmember.h"         // PyMemberDef
@@ -31,20 +32,6 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
     assert(qualname != NULL);
     Py_INCREF(qualname);
 
-    PyObject *consts = code_obj->co_consts;
-    assert(consts == NULL || PyTuple_Check(consts));
-    PyObject *doc;
-    if (consts != NULL && PyTuple_Size(consts) >= 1) {
-        doc = PyTuple_GetItem(consts, 0);
-        if (!PyUnicode_Check(doc)) {
-            doc = Py_None;
-        }
-    }
-    else {
-        doc = Py_None;
-    }
-    Py_INCREF(doc);
-
     // __module__: Use globals['__name__'] if it exists, or NULL.
     _Py_IDENTIFIER(__name__);
     PyObject *module = _PyDict_GetItemIdWithError(globals, &PyId___name__);
@@ -75,7 +62,7 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
     op->func_defaults = NULL;    // No default positional arguments
     op->func_kwdefaults = NULL;  // No default keyword arguments
     op->func_closure = NULL;
-    op->func_doc = doc;
+    op->func_doc = NULL;
     op->func_dict = NULL;
     op->func_weakreflist = NULL;
     op->func_module = module;
@@ -90,7 +77,6 @@ PyFunction_NewWithQualName(PyObject *code, PyObject *globals, PyObject *qualname
     Py_DECREF(code_obj);
     Py_DECREF(name);
     Py_DECREF(qualname);
-    Py_DECREF(doc);
     Py_XDECREF(module);
     Py_XDECREF(builtins);
     return NULL;
@@ -279,7 +265,6 @@ PyFunction_SetAnnotations(PyObject *op, PyObject *annotations)
 
 static PyMemberDef func_memberlist[] = {
     {"__closure__",   T_OBJECT,     OFF(func_closure), READONLY},
-    {"__doc__",       T_OBJECT,     OFF(func_doc), 0},
     {"__globals__",   T_OBJECT,     OFF(func_globals), READONLY},
     {"__module__",    T_OBJECT,     OFF(func_module), 0},
     {"__builtins__",  T_OBJECT,     OFF(func_builtins), READONLY},
@@ -510,6 +495,37 @@ func_set_annotations(PyFunctionObject *op, PyObject *value, void *Py_UNUSED(igno
     return 0;
 }
 
+static PyObject *
+func_get_doc(PyFunctionObject *op, void *Py_UNUSED(ignored))
+{
+    PyObject *doc = op->func_doc;
+    if (doc == NULL) {
+        PyCodeObject *code = (PyCodeObject *)op->func_code;
+        if (!_PyCode_IsHydrated(code)) {
+            if (_PyCode_Hydrate(code) == NULL) {
+                return NULL;
+            }
+        }
+        if (PyTuple_CheckExact(code->co_consts)
+                && PyTuple_GET_SIZE(code->co_consts) >= 1) {
+            doc = PyTuple_GET_ITEM(code->co_consts, 0);
+        }
+    }
+    if (doc == NULL) {
+        doc = Py_None;
+    }
+    Py_INCREF(doc);
+    return doc;
+}
+
+static int
+func_set_doc(PyFunctionObject *op, PyObject *value, void *Py_UNUSED(ignored))
+{
+    Py_INCREF(value);
+    Py_XSETREF(op->func_doc, value);
+    return 0;
+}
+
 static PyGetSetDef func_getsetlist[] = {
     {"__code__", (getter)func_get_code, (setter)func_set_code},
     {"__defaults__", (getter)func_get_defaults,
@@ -521,6 +537,7 @@ static PyGetSetDef func_getsetlist[] = {
     {"__dict__", PyObject_GenericGetDict, PyObject_GenericSetDict},
     {"__name__", (getter)func_get_name, (setter)func_set_name},
     {"__qualname__", (getter)func_get_qualname, (setter)func_set_qualname},
+    {"__doc__", (getter)func_get_doc, (setter)func_set_doc},
     {NULL} /* Sentinel */
 };
 
