bpo-29456: Fix bugs in unicodedata.normalize: u1176, u11a7 and u11c3 (GH-1958) (GH-7704)

Hangul composition check boundaries are wrong for the second character
([0x1161, 0x1176) instead of [0x1161, 0x1176]) and third character ((0x11A7, 0x11C3)
instead of [0x11A7, 0x11C3])..
(cherry picked from commit d134809c)
Co-authored-by: Wonsup Yoon <pusnow@me.com>

Lib/test/test_unicodedata.py

@@ -204,6 +204,19 @@ class UnicodeFunctionsTest(UnicodeDatabaseTest):
         b = u'C\u0338' * 20  + u'\xC7'
         self.assertEqual(self.db.normalize('NFC', a), b)
 
+    def test_issue29456(self):
+        # Fix #29456
+        u1176_str_a = u'\u1100\u1176\u11a8'
+        u1176_str_b = u'\u1100\u1176\u11a8'
+        u11a7_str_a = u'\u1100\u1175\u11a7'
+        u11a7_str_b = u'\uae30\u11a7'
+        u11c3_str_a = u'\u1100\u1175\u11c3'
+        u11c3_str_b = u'\uae30\u11c3'
+        self.assertEqual(self.db.normalize('NFC', u1176_str_a), u1176_str_b)
+        self.assertEqual(self.db.normalize('NFC', u11a7_str_a), u11a7_str_b)
+        self.assertEqual(self.db.normalize('NFC', u11c3_str_a), u11c3_str_b)
+
+
     def test_east_asian_width(self):
         eaw = self.db.east_asian_width
         self.assertRaises(TypeError, eaw, 'a')

Misc/ACKS

@@ -1578,6 +1578,7 @@ Jason Yeo
 EungJun Yi
 Bob Yodlowski
 Danny Yoo
+Wonsup Yoon
 Rory Yorke
 George Yoshida
 Kazuhiro Yoshida

Misc/NEWS.d/next/Library/2017-08-24-17-55-39.bpo-29456.XaB3MP.rst

+Fix bugs in hangul normalization: u1176, u11a7 and u11c3

Modules/unicodedata.c

@@ -664,14 +664,18 @@ nfc_nfkc(PyObject *self, PyObject *input, int k)
          pairs, since we always have decomposed data. */
       if (LBase <= *i && *i < (LBase+LCount) &&
           i + 1 < end &&
-          VBase <= i[1] && i[1] <= (VBase+VCount)) {
+          VBase <= i[1] && i[1] < (VBase+VCount)) {
+          /* check L character is a modern leading consonant (0x1100 ~ 0x1112)
+             and V character is a modern vowel (0x1161 ~ 0x1175). */
           int LIndex, VIndex;
           LIndex = i[0] - LBase;
           VIndex = i[1] - VBase;
           code = SBase + (LIndex*VCount+VIndex)*TCount;
           i+=2;
           if (i < end &&
-              TBase <= *i && *i <= (TBase+TCount)) {
+              TBase < *i && *i < (TBase+TCount)) {
+              /* check T character is a modern trailing consonant
+                 (0x11A8 ~ 0x11C2). */
               code += *i-TBase;
               i++;
           }