3 files changed, 28 insertions, 3 deletions
diff --git a/src/corelib/tools/qlocale.cpp b/src/corelib/tools/qlocale.cpp
index 98e38ca587..3754a1bfcf 100644
--- a/src/corelib/tools/qlocale.cpp
+++ b/src/corelib/tools/qlocale.cpp
@@ -2404,6 +2404,13 @@ Qt::LayoutDirection QLocale::textDirection() const
   \since 4.8
 
   Returns an uppercase copy of \a str.
+
+  If Qt Core is using the ICU libraries, they will be used to perform
+  the transformation according to the rules of the current locale.
+  Otherwise the conversion may be done in a platform-dependent manner,
+  with QString::toUpper() as a generic fallback.
+
+  \sa QString::toUpper()
 */
 QString QLocale::toUpper(const QString &str) const
 {
@@ -2421,6 +2428,13 @@ QString QLocale::toUpper(const QString &str) const
   \since 4.8
 
   Returns a lowercase copy of \a str.
+
+  If Qt Core is using the ICU libraries, they will be used to perform
+  the transformation according to the rules of the current locale.
+  Otherwise the conversion may be done in a platform-dependent manner,
+  with QString::toLower() as a generic fallback.
+
+  \sa QString::toLower()
 */
 QString QLocale::toLower(const QString &str) const
 {
diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 2552a04e55..4babfe1e19 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -763,6 +763,13 @@ QT_BEGIN_NAMESPACE
         The match is constrained to start exactly at the offset passed to
         match() in order to be successful, even if the pattern string does not
         contain any metacharacter that anchors the match at that point.
+
+    \value DontCheckSubjectStringMatchOption
+        The subject string is not checked for UTF-16 validity before
+        attempting a match. Use this option with extreme caution, as
+        attempting to match an invalid string may crash the program and/or
+        constitute a security issue. This enum value has been introduced in
+        Qt 5.4.
 */
 
 // after how many usages we optimize the regexp
@@ -1221,7 +1228,8 @@ static int pcre16SafeExec(const pcre16 *code, const pcre16_extra *extra,
     options \a matchOptions and returns the QRegularExpressionMatchPrivate of
     the result. It also advances a match if a previous result is given as \a
     previous. The \a subject string goes a Unicode validity check if
-    \a checkSubjectString is CheckSubjectString (PCRE doesn't like illegal
+    \a checkSubjectString is CheckSubjectString and the match options don't
+    include DontCheckSubjectStringMatchOption (PCRE doesn't like illegal
     UTF-16 sequences).
 
     Advancing a match is a tricky algorithm. If the previous match matched a
@@ -1290,8 +1298,10 @@ QRegularExpressionMatchPrivate *QRegularExpressionPrivate::doMatch(const QString
     else if (matchType == QRegularExpression::PartialPreferFirstMatch)
         pcreOptions |= PCRE_PARTIAL_HARD;
 
-    if (checkSubjectStringOption == DontCheckSubjectString)
+    if (checkSubjectStringOption == DontCheckSubjectString
+            || matchOptions & QRegularExpression::DontCheckSubjectStringMatchOption) {
         pcreOptions |= PCRE_NO_UTF16_CHECK;
+    }
 
     bool previousMatchWasEmpty = false;
     if (previous && previous->hasMatch &&
diff --git a/src/corelib/tools/qregularexpression.h b/src/corelib/tools/qregularexpression.h
index bf75d12a05..3352e2b3d5 100644
--- a/src/corelib/tools/qregularexpression.h
+++ b/src/corelib/tools/qregularexpression.h
@@ -110,7 +110,8 @@ public:
 
     enum MatchOption {
         NoMatchOption              = 0x0000,
-        AnchoredMatchOption        = 0x0001
+        AnchoredMatchOption        = 0x0001,
+        DontCheckSubjectStringMatchOption = 0x0002
     };
     Q_DECLARE_FLAGS(MatchOptions, MatchOption)