Issue #23275: Allow () = iterable assignment syntax

Documentation updates by Martin Panter.

4 files changed, 21 insertions, 18 deletions

diff --git a/Lib/test/test_codeop.py b/Lib/test/test_codeop.py
index 509bf5d..98da26f 100644
--- a/Lib/test/test_codeop.py
+++ b/Lib/test/test_codeop.py
@@ -282,7 +282,6 @@ class CodeopTests(unittest.TestCase):
         ai("if (a == 1 and b = 2): pass")
 
         ai("del 1")
-        ai("del ()")
         ai("del (1,)")
         ai("del [1]")
         ai("del '1'")
diff --git a/Lib/test/test_syntax.py b/Lib/test/test_syntax.py
index 057441c..38fc417 100644
--- a/Lib/test/test_syntax.py
+++ b/Lib/test/test_syntax.py
@@ -35,14 +35,6 @@ SyntaxError: invalid syntax
 Traceback (most recent call last):
 SyntaxError: can't assign to keyword
 
-It's a syntax error to assign to the empty tuple.  Why isn't it an
-error to assign to the empty list?  It will always raise some error at
-runtime.
-
->>> () = 1
-Traceback (most recent call last):
-SyntaxError: can't assign to ()
-
 >>> f() = 1
 Traceback (most recent call last):
 SyntaxError: can't assign to function call
@@ -491,10 +483,6 @@ Traceback (most recent call last):
    ...
 SyntaxError: keyword argument repeated
 
->>> del ()
-Traceback (most recent call last):
-SyntaxError: can't delete ()
-
 >>> {1, 2, 3} = 42
 Traceback (most recent call last):
 SyntaxError: can't assign to literal
diff --git a/Lib/test/test_unpack.py b/Lib/test/test_unpack.py
index d1ccb38..3fcb18f 100644
--- a/Lib/test/test_unpack.py
+++ b/Lib/test/test_unpack.py
@@ -117,6 +117,27 @@ error)
       ...
     test.test_unpack.BozoError
 
+Allow unpacking empty iterables
+
+    >>> () = []
+    >>> [] = ()
+    >>> [] = []
+    >>> () = ()
+
+Unpacking non-iterables should raise TypeError
+
+    >>> () = 42
+    Traceback (most recent call last):
+      ...
+    TypeError: 'int' object is not iterable
+
+Unpacking to an empty iterable should raise ValueError
+
+    >>> () = [42]
+    Traceback (most recent call last):
+      ...
+    ValueError: too many values to unpack (expected 0)
+
 """
 
 __test__ = {'doctests' : doctests}
diff --git a/Lib/test/test_with.py b/Lib/test/test_with.py
index 3815062..e247ff6 100644
--- a/Lib/test/test_with.py
+++ b/Lib/test/test_with.py
@@ -140,11 +140,6 @@ class FailureTestCase(unittest.TestCase):
             'with mock as (None):\n'
             '  pass')
 
-    def testAssignmentToEmptyTupleError(self):
-        self.assertRaisesSyntaxError(
-            'with mock as ():\n'
-            '  pass')
-
     def testAssignmentToTupleOnlyContainingNoneError(self):
         self.assertRaisesSyntaxError('with mock as None,:\n  pass')
         self.assertRaisesSyntaxError(