#5057: the peepholer no longer optimizes subscription on unicode literals (e.g. u...

diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
index 3e8b7ae9a4d93b2dc6d96496ed9b4630f04ad3d9..7e05f49737f5575dc09ac16b2260d76f4fc56ce8 100644 (file)
--- a/Lib/test/test_peepholer.py
+++ b/Lib/test/test_peepholer.py
@@ -138,21 +138,22 @@ class TestTranforms(unittest.TestCase):
         self.assertIn('(1000)', asm)
 
     def test_binary_subscr_on_unicode(self):
-        # valid code get optimized
+        # unicode strings don't get optimized
         asm = dis_single('u"foo"[0]')
-        self.assertIn("(u'f')", asm)
-        self.assertNotIn('BINARY_SUBSCR', asm)
+        self.assertNotIn("(u'f')", asm)
+        self.assertIn('BINARY_SUBSCR', asm)
         asm = dis_single('u"\u0061\uffff"[1]')
-        self.assertIn("(u'\\uffff')", asm)
-        self.assertNotIn('BINARY_SUBSCR', asm)
+        self.assertNotIn("(u'\\uffff')", asm)
+        self.assertIn('BINARY_SUBSCR', asm)
 
-        # invalid code doesn't get optimized
         # out of range
         asm = dis_single('u"fuu"[10]')
         self.assertIn('BINARY_SUBSCR', asm)
         # non-BMP char (see #5057)
         asm = dis_single('u"\U00012345"[0]')
         self.assertIn('BINARY_SUBSCR', asm)
+        asm = dis_single('u"\U00012345abcdef"[3]')
+        self.assertIn('BINARY_SUBSCR', asm)
 
 
     def test_folding_of_unaryops_on_constants(self):

diff --git a/Misc/NEWS b/Misc/NEWS
index 9716c6def3f41a617700b4e01974dec6e97e57a0..bd73d0adf28e369b6b8a971859a01e274c37a80b 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -9,6 +9,10 @@ What's New in Python 2.7.4
 Core and Builtins
 -----------------
 
+- Issue #5057: the peepholer no longer optimize subscription on unicode
+  literals (e.g. u'foo'[0]) in order to produce compatible pyc files between
+  narrow and wide builds.
+
 - Issue #8401: assigning an int to a bytearray slice (e.g. b[3:4] = 5) now
   raises an error.
 

diff --git a/Python/peephole.c b/Python/peephole.c
index ae84efa996e8ce7ff6d7a6e9e26369789860f619..fb6cd03c8685a86c5b20b37dfb511f9a6d7f4882 100644 (file)
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -128,27 +128,14 @@ fold_binops_on_constants(unsigned char *codestr, PyObject *consts)
             newconst = PyNumber_Subtract(v, w);
             break;
         case BINARY_SUBSCR:
-            newconst = PyObject_GetItem(v, w);
             /* #5057: if v is unicode, there might be differences between
-               wide and narrow builds in cases like u'\U00012345'[0].
-               Wide builds will return a non-BMP char, whereas narrow builds
-               will return a surrogate.  In both the cases skip the
-               optimization in order to produce compatible pycs.
-             */
-#ifdef Py_USING_UNICODE
-            if (newconst != NULL &&
-                PyUnicode_Check(v) && PyUnicode_Check(newconst)) {
-                Py_UNICODE ch = PyUnicode_AS_UNICODE(newconst)[0];
-#ifdef Py_UNICODE_WIDE
-                if (ch > 0xFFFF) {
-#else
-                if (ch >= 0xD800 && ch <= 0xDFFF) {
-#endif
-                    Py_DECREF(newconst);
-                    return 0;
-                }
-            }
-#endif
+               wide and narrow builds in cases like '\U00012345'[0] or
+               '\U00012345abcdef'[3], so it's better to skip the optimization
+               in order to produce compatible pycs.
+            */
+            if (PyUnicode_Check(v))
+                return 0;
+            newconst = PyObject_GetItem(v, w);
             break;
         case BINARY_LSHIFT:
             newconst = PyNumber_Lshift(v, w);