Bug #1557232: fix seg fault with def f((((x)))) and def f(((x),)).

These tests should be improved.  Hopefully this fixes variations when
flipping back and forth between fpdef and fplist.

Backport candidate.

Lib/test/test_complex_args.py

@@ -0,0 +1,91 @@
+
+import unittest
+from test import test_support
+
+class ComplexArgsTestCase(unittest.TestCase):
+
+    def check(self, func, expected, *args):
+        self.assertEqual(func(*args), expected)
+
+    # These functions are tested below as lambdas too.  If you add a function test,
+    # also add a similar lambda test.
+
+    def test_func_parens_no_unpacking(self):
+        def f(((((x))))): return x
+        self.check(f, 1, 1)
+        # Inner parens are elided, same as: f(x,)
+        def f(((x)),): return x
+        self.check(f, 2, 2)
+
+    def test_func_1(self):
+        def f(((((x),)))): return x
+        self.check(f, 3, (3,))
+        def f(((((x)),))): return x
+        self.check(f, 4, (4,))
+        def f(((((x))),)): return x
+        self.check(f, 5, (5,))
+        def f(((x),)): return x
+        self.check(f, 6, (6,))
+
+    def test_func_2(self):
+        def f(((((x)),),)): return x
+        self.check(f, 2, ((2,),))
+
+    def test_func_3(self):
+        def f((((((x)),),),)): return x
+        self.check(f, 3, (((3,),),))
+
+    def test_func_complex(self):
+        def f((((((x)),),),), a, b, c): return x, a, b, c
+        self.check(f, (3, 9, 8, 7), (((3,),),), 9, 8, 7)
+
+        def f(((((((x)),)),),), a, b, c): return x, a, b, c
+        self.check(f, (3, 9, 8, 7), (((3,),),), 9, 8, 7)
+
+        def f(a, b, c, ((((((x)),)),),)): return a, b, c, x
+        self.check(f, (9, 8, 7, 3), 9, 8, 7, (((3,),),))
+
+    # Duplicate the tests above, but for lambda.  If you add a lambda test,
+    # also add a similar function test above.
+
+    def test_lambda_parens_no_unpacking(self):
+        f = lambda (((((x))))): x
+        self.check(f, 1, 1)
+        # Inner parens are elided, same as: f(x,)
+        f = lambda ((x)),: x
+        self.check(f, 2, 2)
+
+    def test_lambda_1(self):
+        f = lambda (((((x),)))): x
+        self.check(f, 3, (3,))
+        f = lambda (((((x)),))): x
+        self.check(f, 4, (4,))
+        f = lambda (((((x))),)): x
+        self.check(f, 5, (5,))
+        f = lambda (((x),)): x
+        self.check(f, 6, (6,))
+
+    def test_lambda_2(self):
+        f = lambda (((((x)),),)): x
+        self.check(f, 2, ((2,),))
+
+    def test_lambda_3(self):
+        f = lambda ((((((x)),),),)): x
+        self.check(f, 3, (((3,),),))
+
+    def test_lambda_complex(self):
+        f = lambda (((((x)),),),), a, b, c: (x, a, b, c)
+        self.check(f, (3, 9, 8, 7), (((3,),),), 9, 8, 7)
+
+        f = lambda ((((((x)),)),),), a, b, c: (x, a, b, c)
+        self.check(f, (3, 9, 8, 7), (((3,),),), 9, 8, 7)
+
+        f = lambda a, b, c, ((((((x)),)),),): (a, b, c, x)
+        self.check(f, (9, 8, 7, 3), 9, 8, 7, (((3,),),))
+
+
+def test_main():
+    test_support.run_unittest(ComplexArgsTestCase)
+
+if __name__ == "__main__":
+    test_main()