1 files changed, 37 insertions, 32 deletions

diff --git a/src/corelib/codecs/qtextcodec.cpp b/src/corelib/codecs/qtextcodec.cpp
index b7bb3196af..06fd88da90 100644
--- a/src/corelib/codecs/qtextcodec.cpp
+++ b/src/corelib/codecs/qtextcodec.cpp
@@ -47,6 +47,7 @@
 #include "qendian.h"
 #include "qfile.h"
 #include "qlist.h"
+#include <private/qlocking_p.h>
 #include "qstringlist.h"
 #include "qvarlengtharray.h"
 #if !defined(QT_BOOTSTRAPPED)
@@ -86,7 +87,7 @@
 #endif // icu
 #endif // QT_BOOTSTRAPPED
 
-#include "qmutex.h"
+#include <mutex>
 
 #include <stdlib.h>
 #include <ctype.h>
@@ -100,8 +101,16 @@ QT_BEGIN_NAMESPACE
 typedef QList<QTextCodec*>::ConstIterator TextCodecListConstIt;
 typedef QList<QByteArray>::ConstIterator ByteArrayListConstIt;
 
-Q_GLOBAL_STATIC_WITH_ARGS(QMutex, textCodecsMutex, (QMutex::Recursive));
-QMutex *qTextCodecsMutex() { return textCodecsMutex(); }
+Q_GLOBAL_STATIC(QRecursiveMutex, textCodecsMutex);
+
+class TextCodecsMutexLocker
+{
+    using Lock = decltype(qt_unique_lock(std::declval<QRecursiveMutex&>()));
+    // ### FIXME: this is used when textCodecsMutex already == nullptr
+    const Lock lock = qt_unique_lock(textCodecsMutex());
+public:
+    TextCodecsMutexLocker() {} // required d/t an ICC 19 bug
+};
 
 #if !QT_CONFIG(icu)
 static char qtolower(char c)
@@ -159,10 +168,10 @@ static QTextCodec *setupLocaleMapper()
 {
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
 
-    QTextCodec *locale = 0;
+    QTextCodec *locale = nullptr;
 
     {
-        QMutexLocker locker(textCodecsMutex());
+        const TextCodecsMutexLocker locker;
         if (globalData->allCodecs.isEmpty())
             setup();
     }
@@ -208,7 +217,7 @@ static QTextCodec *setupLocaleMapper()
         // First part is getting that locale name.  First try setlocale() which
         // definitely knows it, but since we cannot fully trust it, get ready
         // to fall back to environment variables.
-        const QByteArray ctype = setlocale(LC_CTYPE, 0);
+        const QByteArray ctype = setlocale(LC_CTYPE, nullptr);
 
         // Get the first nonempty value from $LC_ALL, $LC_CTYPE, and $LANG
         // environment variables.
@@ -477,7 +486,7 @@ QTextCodec::ConverterState::~ConverterState()
 */
 QTextCodec::QTextCodec()
 {
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     QCoreGlobalData *globalInstance = QCoreGlobalData::instance();
     if (globalInstance->allCodecs.isEmpty())
@@ -501,7 +510,7 @@ QTextCodec::~QTextCodec()
 
     globalData->codecForLocale.testAndSetRelaxed(this, nullptr);
 
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     globalData->allCodecs.removeOne(this);
 
@@ -532,23 +541,21 @@ QTextCodec::~QTextCodec()
 QTextCodec *QTextCodec::codecForName(const QByteArray &name)
 {
     if (name.isEmpty())
-        return 0;
+        return nullptr;
 
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
     if (!globalData)
-        return 0;
+        return nullptr;
     setup();
 
 #if !QT_CONFIG(icu)
     QTextCodecCache *cache = &globalData->codecCache;
     QTextCodec *codec;
-    if (cache) {
-        codec = cache->value(name);
-        if (codec)
-            return codec;
-    }
+    codec = cache->value(name);
+    if (codec)
+        return codec;
 
     for (TextCodecListConstIt it = globalData->allCodecs.constBegin(), cend = globalData->allCodecs.constEnd(); it != cend; ++it) {
         QTextCodec *cursor = *it;
@@ -560,14 +567,13 @@ QTextCodec *QTextCodec::codecForName(const QByteArray &name)
         QList<QByteArray> aliases = cursor->aliases();
         for (ByteArrayListConstIt ait = aliases.constBegin(), acend = aliases.constEnd(); ait != acend; ++ait) {
             if (qTextCodecNameMatch(*ait, name)) {
-                if (cache)
-                    cache->insert(name, cursor);
+                cache->insert(name, cursor);
                 return cursor;
             }
         }
     }
 
-    return 0;
+    return nullptr;
 #else
     return QIcuCodec::codecForNameUnlocked(name);
 #endif
@@ -581,11 +587,11 @@ QTextCodec *QTextCodec::codecForName(const QByteArray &name)
 */
 QTextCodec* QTextCodec::codecForMib(int mib)
 {
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
     if (!globalData)
-        return 0;
+        return nullptr;
     if (globalData->allCodecs.isEmpty())
         setup();
 
@@ -611,7 +617,7 @@ QTextCodec* QTextCodec::codecForMib(int mib)
 #if QT_CONFIG(icu)
     return QIcuCodec::codecForMibUnlocked(mib);
 #else
-    return 0;
+    return nullptr;
 #endif
 }
 
@@ -627,7 +633,7 @@ QTextCodec* QTextCodec::codecForMib(int mib)
 */
 QList<QByteArray> QTextCodec::availableCodecs()
 {
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
     if (globalData->allCodecs.isEmpty())
@@ -659,7 +665,7 @@ QList<int> QTextCodec::availableMibs()
 #if QT_CONFIG(icu)
     return QIcuCodec::availableMibs();
 #else
-    QMutexLocker locker(textCodecsMutex());
+    const TextCodecsMutexLocker locker;
 
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
     if (globalData->allCodecs.isEmpty())
@@ -704,14 +710,13 @@ QTextCodec* QTextCodec::codecForLocale()
 {
     QCoreGlobalData *globalData = QCoreGlobalData::instance();
     if (!globalData)
-        return 0;
+        return nullptr;
 
     QTextCodec *codec = globalData->codecForLocale.loadAcquire();
     if (!codec) {
 #if QT_CONFIG(icu)
-        textCodecsMutex()->lock();
+        const TextCodecsMutexLocker locker;
         codec = QIcuCodec::defaultCodecUnlocked();
-        textCodecsMutex()->unlock();
 #else
         // setupLocaleMapper locks as necessary
         codec = setupLocaleMapper();
@@ -830,7 +835,7 @@ QTextEncoder* QTextCodec::makeEncoder(QTextCodec::ConversionFlags flags) const
 */
 QByteArray QTextCodec::fromUnicode(const QString& str) const
 {
-    return convertFromUnicode(str.constData(), str.length(), 0);
+    return convertFromUnicode(str.constData(), str.length(), nullptr);
 }
 #endif
 
@@ -863,7 +868,7 @@ QByteArray QTextCodec::fromUnicode(QStringView str) const
 */
 QString QTextCodec::toUnicode(const QByteArray& a) const
 {
-    return convertToUnicode(a.constData(), a.length(), 0);
+    return convertToUnicode(a.constData(), a.length(), nullptr);
 }
 
 /*!
@@ -915,7 +920,7 @@ bool QTextCodec::canEncode(QStringView s) const
 QString QTextCodec::toUnicode(const char *chars) const
 {
     int len = qstrlen(chars);
-    return convertToUnicode(chars, len, 0);
+    return convertToUnicode(chars, len, nullptr);
 }
 
 
@@ -1061,7 +1066,7 @@ QString QTextDecoder::toUnicode(const char *chars, int len)
 }
 
 // in qstring.cpp:
-void qt_from_latin1(ushort *dst, const char *str, size_t size) Q_DECL_NOTHROW;
+void qt_from_latin1(ushort *dst, const char *str, size_t size) noexcept;
 
 /*! \overload
 
@@ -1110,7 +1115,7 @@ QString QTextDecoder::toUnicode(const QByteArray &ba)
 QTextCodec *QTextCodec::codecForHtml(const QByteArray &ba, QTextCodec *defaultCodec)
 {
     // determine charset
-    QTextCodec *c = QTextCodec::codecForUtfText(ba, 0);
+    QTextCodec *c = QTextCodec::codecForUtfText(ba, nullptr);
     if (!c) {
         static Q_RELAXED_CONSTEXPR auto matcher = qMakeStaticByteArrayMatcher("meta ");
         QByteArray header = ba.left(1024).toLower();