code_richcompare() now uses the constants types

Issue #25843: When compiling code, don't merge constants if they are equal but
have a different types. For example, "f1, f2 = lambda: 1, lambda: 1.0" is now
correctly compiled to two different functions: f1() returns 1 (int) and f2()
returns 1.0 (int), even if 1 and 1.0 are equal.

Add a new _PyCode_ConstantKey() private function.

Objects/codeobject.c

@@ -409,11 +409,135 @@ code_repr(PyCodeObject *co)
     }
 }
 
+PyObject*
+_PyCode_ConstantKey(PyObject *op)
+{
+    PyObject *key;
+
+    /* Py_None and Py_Ellipsis are singleton */
+    if (op == Py_None || op == Py_Ellipsis
+       || PyLong_CheckExact(op)
+       || PyBool_Check(op)
+       || PyBytes_CheckExact(op)
+       || PyUnicode_CheckExact(op)
+          /* code_richcompare() uses _PyCode_ConstantKey() internally */
+       || PyCode_Check(op)) {
+        key = PyTuple_Pack(2, Py_TYPE(op), op);
+    }
+    else if (PyFloat_CheckExact(op)) {
+        double d = PyFloat_AS_DOUBLE(op);
+        /* all we need is to make the tuple different in either the 0.0
+         * or -0.0 case from all others, just to avoid the "coercion".
+         */
+        if (d == 0.0 && copysign(1.0, d) < 0.0)
+            key = PyTuple_Pack(3, Py_TYPE(op), op, Py_None);
+        else
+            key = PyTuple_Pack(2, Py_TYPE(op), op);
+    }
+    else if (PyComplex_CheckExact(op)) {
+        Py_complex z;
+        int real_negzero, imag_negzero;
+        /* For the complex case we must make complex(x, 0.)
+           different from complex(x, -0.) and complex(0., y)
+           different from complex(-0., y), for any x and y.
+           All four complex zeros must be distinguished.*/
+        z = PyComplex_AsCComplex(op);
+        real_negzero = z.real == 0.0 && copysign(1.0, z.real) < 0.0;
+        imag_negzero = z.imag == 0.0 && copysign(1.0, z.imag) < 0.0;
+        /* use True, False and None singleton as tags for the real and imag
+         * sign, to make tuples different */
+        if (real_negzero && imag_negzero) {
+            key = PyTuple_Pack(3, Py_TYPE(op), op, Py_True);
+        }
+        else if (imag_negzero) {
+            key = PyTuple_Pack(3, Py_TYPE(op), op, Py_False);
+        }
+        else if (real_negzero) {
+            key = PyTuple_Pack(3, Py_TYPE(op), op, Py_None);
+        }
+        else {
+            key = PyTuple_Pack(2, Py_TYPE(op), op);
+        }
+    }
+    else if (PyTuple_CheckExact(op)) {
+        Py_ssize_t i, len;
+        PyObject *tuple;
+
+        len = PyTuple_GET_SIZE(op);
+        tuple = PyTuple_New(len);
+        if (tuple == NULL)
+            return NULL;
+
+        for (i=0; i < len; i++) {
+            PyObject *item, *item_key;
+
+            item = PyTuple_GET_ITEM(op, i);
+            item_key = _PyCode_ConstantKey(item);
+            if (item_key == NULL) {
+                Py_DECREF(tuple);
+                return NULL;
+            }
+
+            PyTuple_SET_ITEM(tuple, i, item_key);
+        }
+
+        key = PyTuple_Pack(3, Py_TYPE(op), op, tuple);
+        Py_DECREF(tuple);
+    }
+    else if (PyFrozenSet_CheckExact(op)) {
+        Py_ssize_t pos = 0;
+        PyObject *item;
+        Py_hash_t hash;
+        Py_ssize_t i, len;
+        PyObject *tuple, *set;
+
+        len = PySet_GET_SIZE(op);
+        tuple = PyTuple_New(len);
+        if (tuple == NULL)
+            return NULL;
+
+        i = 0;
+        while (_PySet_NextEntry(op, &pos, &item, &hash)) {
+            PyObject *item_key;
+
+            item_key = _PyCode_ConstantKey(item);
+            if (item_key == NULL) {
+                Py_DECREF(tuple);
+                return NULL;
+            }
+
+            assert(i < len);
+            PyTuple_SET_ITEM(tuple, i, item_key);
+            i++;
+        }
+        set = PyFrozenSet_New(tuple);
+        Py_DECREF(tuple);
+        if (set == NULL)
+            return NULL;
+
+        key = PyTuple_Pack(3, Py_TYPE(op), op, set);
+        Py_DECREF(set);
+        return key;
+    }
+    else {
+        /* for other types, use the object identifier as an unique identifier
+         * to ensure that they are seen as unequal. */
+        PyObject *obj_id = PyLong_FromVoidPtr(op);
+        if (obj_id == NULL)
+            return NULL;
+
+        key = PyTuple_Pack(3, Py_TYPE(op), op, obj_id);
+        Py_DECREF(obj_id);
+    }
+    return key;
+}
+
 static PyObject *
 code_richcompare(PyObject *self, PyObject *other, int op)
 {
     PyCodeObject *co, *cp;
     int eq;
+    PyObject *consts1, *consts2;
     PyObject *res;
 
     if ((op != Py_EQ && op != Py_NE) ||
@@ -439,8 +563,21 @@ code_richcompare(PyObject *self, PyObject *other, int op)
     if (!eq) goto unequal;
     eq = PyObject_RichCompareBool(co->co_code, cp->co_code, Py_EQ);
     if (eq <= 0) goto unequal;
-    eq = PyObject_RichCompareBool(co->co_consts, cp->co_consts, Py_EQ);
+
+    /* compare constants */
+    consts1 = _PyCode_ConstantKey(co->co_consts);
+    if (!consts1)
+        return NULL;
+    consts2 = _PyCode_ConstantKey(cp->co_consts);
+    if (!consts2) {
+        Py_DECREF(consts1);
+        return NULL;
+    }
+    eq = PyObject_RichCompareBool(consts1, consts2, Py_EQ);
+    Py_DECREF(consts1);
+    Py_DECREF(consts2);
     if (eq <= 0) goto unequal;
+
     eq = PyObject_RichCompareBool(co->co_names, cp->co_names, Py_EQ);
     if (eq <= 0) goto unequal;
     eq = PyObject_RichCompareBool(co->co_varnames, cp->co_varnames, Py_EQ);