Two fixes for extended call syntax:

If a non-tuple sequence is passed as the *arg, convert it to a tuple
before checking its length.
If named keyword arguments are used in combination with **kwargs, make
a copy of kwargs before inserting the new keys.

Lib/test/output/test_extcall

@@ -16,6 +16,10 @@ TypeError: not enough arguments; expected 1, got 0
 1 (2,) {}
 1 (2, 3) {}
 1 (2, 3, 4, 5) {}
+0 (1, 2) {}
+1 () {'d': 4, 'b': 2, 'c': 3, 'a': 1}
+{'b': 2, 'c': 3, 'a': 1}
+{'b': 2, 'c': 3, 'a': 1}
 keyword parameter redefined: x
 keyword parameter redefined: b
 keywords must be strings

Lib/test/test_extcall.py

@@ -46,6 +46,50 @@ g(1)
 g(1, 2)
 g(1, 2, 3)
 g(1, 2, 3, *(4, 5))
+class Nothing: pass
+try:
+    g(*Nothing())
+except AttributeError, attr:
+    assert attr[0] == '__len__'
+else:
+    print "should raise AttributeError: __len__"
+
+class Nothing:
+    def __len__(self):
+        return 5
+try:
+    g(*Nothing())
+except AttributeError, attr:
+    assert attr[0] == '__getitem__'
+else:
+    print "should raise AttributeError: __getitem__"
+    
+class Nothing:
+    def __len__(self):
+        return 5
+    def __getitem__(self, i):
+        if i < 3:
+            return i
+        else:
+            raise IndexError, i
+g(*Nothing())
+
+# make sure the function call doesn't stomp on the dictionary?
+d = {'a': 1, 'b': 2, 'c': 3}
+d2 = d.copy()
+assert d == d2
+g(1, d=4, **d)
+print d
+print d2
+assert d == d2, "function call modified dictionary"
+
+# what about willful misconduct?
+def saboteur(**kw):
+    kw['x'] = locals()
+d = {}
+saboteur(a=1, **d)
+assert d == {}
+        
 try:
     g(1, 2, 3, **{'x':4, 'y':5})
 except TypeError, err:

Python/ceval.c

@@ -1635,7 +1635,18 @@ eval_code2(co, globals, locals,
 				x = NULL;
 				break;
 			    }
-			    nstar = PySequence_Length(stararg);
+			    /* Convert abstract sequence to concrete tuple */
+			    if (!PyTuple_Check(stararg)) {
+				PyObject *t = NULL;
+				t = PySequence_Tuple(stararg);
+				if (t == NULL) {
+				    x = NULL;
+				    break;
+				}
+				Py_DECREF(stararg);
+				stararg = t;
+			    }
+			    nstar = PyTuple_GET_SIZE(stararg);
 			    if (nstar < 0) {
 				x = NULL;
 				break;
@@ -1649,6 +1660,15 @@ eval_code2(co, globals, locals,
 				    break;
 				}
 			    }
+			    else {
+				    PyObject *d = PyDict_Copy(kwdict);
+				    if (d == NULL) {
+					    x = NULL;
+					    break;
+				    }
+				    Py_DECREF(kwdict);
+				    kwdict = d;
+			    }
 			    err = 0;
 			    while (--nk >= 0) {
 				PyObject *value = POP();
@@ -1678,18 +1698,7 @@ eval_code2(co, globals, locals,
 			    break;
 			}
 			if (stararg) {
-			    PyObject *t = NULL;
 			    int i;
-			    if (!PyTuple_Check(stararg)) {
-				/* must be sequence to pass earlier test */
-				t = PySequence_Tuple(stararg);
-				if (t == NULL) {
-				    x = NULL;
-				    break;
-				}
-				Py_DECREF(stararg);
-				stararg = t;
-			    }
 			    for (i = 0; i < nstar; i++) {
 				PyObject *a = PyTuple_GET_ITEM(stararg, i);
 				Py_INCREF(a);