1 files changed, 13 insertions, 5 deletions

diff --git a/src/corelib/tools/qchar.cpp b/src/corelib/tools/qchar.cpp
index 9db7d1a..b296129 100644
--- a/src/corelib/tools/qchar.cpp
+++ b/src/corelib/tools/qchar.cpp
@@ -1481,7 +1481,8 @@ static void decomposeHelper(QString *str, bool canonical, QChar::UnicodeVersion
                 ucs4 = QChar::surrogateToUcs4(high, ucs4);
             }
         }
-        if (QChar::unicodeVersion(ucs4) > version)
+        QChar::UnicodeVersion v = QChar::unicodeVersion(ucs4);
+        if (v == QChar::Unicode_Unassigned || v > version)
             continue;
         int length;
         int tag;
@@ -1541,7 +1542,7 @@ static ushort ligatureHelper(ushort u1, ushort u2)
     return 0;
 }
 
-static void composeHelper(QString *str, int from)
+static void composeHelper(QString *str, QChar::UnicodeVersion version, int from)
 {
     QString &s = *str;
 
@@ -1561,7 +1562,14 @@ static void composeHelper(QString *str, int from)
                 ++pos;
             }
         }
-        int combining = QChar::combiningClass(uc);
+        const QUnicodeTables::Properties *p = qGetProp(uc);
+        if (p->unicodeVersion == QChar::Unicode_Unassigned || p->unicodeVersion > version) {
+            starter = -1; // to prevent starter == pos - 1
+            lastCombining = 0;
+            ++pos;
+            continue;
+        }
+        int combining = p->combiningClass;
         if (starter == pos - 1 || combining > lastCombining) {
             // allowed to form ligature with S
             QChar ligature = ligatureHelper(s.at(starter).unicode(), uc);
@@ -1608,7 +1616,7 @@ static void canonicalOrderHelper(QString *str, QChar::UnicodeVersion version, in
         ushort c2 = 0;
         {
             const QUnicodeTables::Properties *p = qGetProp(u2);
-            if ((QChar::UnicodeVersion)p->unicodeVersion <= version)
+            if (p->unicodeVersion != QChar::Unicode_Unassigned && p->unicodeVersion <= version)
                 c2 = p->combiningClass;
         }
         if (c2 == 0) {
@@ -1619,7 +1627,7 @@ static void canonicalOrderHelper(QString *str, QChar::UnicodeVersion version, in
         ushort c1 = 0;
         {
             const QUnicodeTables::Properties *p = qGetProp(u1);
-            if ((QChar::UnicodeVersion)p->unicodeVersion <= version)
+            if (p->unicodeVersion != QChar::Unicode_Unassigned && p->unicodeVersion <= version)
                 c1 = p->combiningClass;
         }