Merge branch 'main' into typevar-subst

serhiy-storchaka · Jul 27, 2021 · Jul 31, 2021 · Aug 2, 2021 · Aug 4, 2021 · Aug 5, 2021
commit a0087e0d44896815c5eba0f0469c3af2d8842597
diff --git a/Include/internal/pycore_global_strings.h b/Include/internal/pycore_global_strings.h
@@ -202,6 +202,9 @@ struct _Py_global_strings {
         STRUCT_FOR_ID(__subclasshook__)
         STRUCT_FOR_ID(__truediv__)
         STRUCT_FOR_ID(__trunc__)
+        STRUCT_FOR_ID(__typing_is_unpacked_typevartuple__)
+        STRUCT_FOR_ID(__typing_prepare_subst__)
+        STRUCT_FOR_ID(__typing_unpacked_tuple_args__)
         STRUCT_FOR_ID(__warningregistry__)
         STRUCT_FOR_ID(__weaklistoffset__)
         STRUCT_FOR_ID(__weakref__)

@@ -824,6 +824,9 @@ extern "C" {
                 INIT_ID(__subclasshook__), \
                 INIT_ID(__truediv__), \
                 INIT_ID(__trunc__), \
+                INIT_ID(__typing_is_unpacked_typevartuple__), \
+                INIT_ID(__typing_prepare_subst__), \
+                INIT_ID(__typing_unpacked_tuple_args__), \
                 INIT_ID(__warningregistry__), \
                 INIT_ID(__weaklistoffset__), \
                 INIT_ID(__weakref__), \

@@ -950,13 +950,12 @@ def __repr__(self):
             prefix = '~'
         return prefix + self.__name__
 
-
     @property
     def __parameters__(self):
         return (self,)
 
-
-class TypeVar(_Final, _Immutable, _BoundVarianceMixin, _root=True):
+class TypeVar(_Final, _Immutable, _BoundVarianceMixin, _PickleUsingNameMixin,
+              _root=True):
     """Type variable.
 
     Usage::
@@ -1065,12 +1064,48 @@ def __repr__(self):
         return self.__name__
 
     def __getitem__(self, arg):
-        raise AssertionError
+        raise TypeError("Substitution of bare TypeVarTuple is not supported")
 
     @property
     def __parameters__(self):
         return (self,)
 
+    def __typing_prepare_subst__(self, alias, args):
+        params = alias.__parameters__
+        typevartuple_index = params.index(self)
+        for param in enumerate(params[typevartuple_index + 1:]):
+            if isinstance(param, TypeVarTuple):
+                raise TypeError(f"More than one TypeVarTuple parameter in {alias}")
+
+        alen = len(args)
+        plen = len(params)
+        left = typevartuple_index
+        right = plen - typevartuple_index - 1
+        var_tuple_index = None
+        fillarg = None
+        for k, arg in enumerate(args):
+            if not (isinstance(arg, type) and not isinstance(arg, GenericAlias)):
+                subargs = getattr(arg, '__typing_unpacked_tuple_args__', None)
+                if subargs and len(subargs) == 2 and subargs[-1] is ...:
+                    if var_tuple_index is not None:
+                        raise TypeError("More than one unpacked arbitrary-length tuple argument")
+                    var_tuple_index = k
+                    fillarg = subargs[0]
+        if var_tuple_index is not None:
+            left = min(left, var_tuple_index)
+            right = min(right, alen - var_tuple_index - 1)
+        elif left + right > alen:
+            raise TypeError(f"Too few arguments for {alias};"
+                            f" actual {alen}, expected at least {plen-1}")
+
+        return (
+            *args[:left],
+            *([fillarg]*(typevartuple_index - left)),
+            tuple(args[left: alen - right]),
+            *([fillarg]*(plen - right - left - typevartuple_index - 1)),
+            *args[alen - right:],
+        )
+
 
 class ParamSpecArgs(_Final, _Immutable, _root=True):
     """The args for a ParamSpec object.

diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c
@@ -443,7 +443,13 @@ _Py_subs_parameters(PyObject *self, PyObject *args, PyObject *parameters, PyObje
     }
     for (Py_ssize_t iarg = 0, jarg = 0; iarg < nargs; iarg++) {
         PyObject *arg = PyTuple_GET_ITEM(args, iarg);
-        arg = subs_tvars(arg, parameters, argitems);
+        int unpack = _is_unpacked_typevartuple(arg);
+        if (unpack < 0) {
+            Py_DECREF(newargs);
+            Py_DECREF(item);
+            return NULL;
+        }
+        arg = subs_tvars(arg, parameters, argitems, nitems);
         if (arg == NULL) {
             Py_DECREF(newargs);
             Py_DECREF(item);