QMimeBinaryProvider: avoid QString creation just to check for isEmpty()

Return a QLatin1String instead and only if that is not empty,
convert it into a QString.

Also saves 320B in text size on optimized GCC 6.1 AMD64 Linux
builds.

Change-Id: I5432d213a6200e45414626bedb9f216bafaf1108
Reviewed-by: David Faure <david.faure@kdab.com>

2 files changed, 5 insertions, 5 deletions

diff --git a/src/corelib/mimetypes/qmimeprovider.cpp b/src/corelib/mimetypes/qmimeprovider.cpp
index 5c0acce4c3..ed7ebb2ef5 100644
--- a/src/corelib/mimetypes/qmimeprovider.cpp
+++ b/src/corelib/mimetypes/qmimeprovider.cpp
@@ -655,7 +655,7 @@ void QMimeBinaryProvider::loadMimeTypePrivate(QMimeTypePrivate &data)
 }
 
 // Binary search in the icons or generic-icons list
-QString QMimeBinaryProvider::iconForMime(CacheFile *cacheFile, int posListOffset, const QByteArray &inputMime)
+QLatin1String QMimeBinaryProvider::iconForMime(CacheFile *cacheFile, int posListOffset, const QByteArray &inputMime)
 {
     const int iconsListOffset = cacheFile->getUint32(posListOffset);
     const int numIcons = cacheFile->getUint32(iconsListOffset);
@@ -676,7 +676,7 @@ QString QMimeBinaryProvider::iconForMime(CacheFile *cacheFile, int posListOffset
             return QLatin1String(cacheFile->getCharStar(iconOffset));
         }
     }
-    return QString();
+    return QLatin1String();
 }
 
 void QMimeBinaryProvider::loadIcon(QMimeTypePrivate &data)
@@ -684,7 +684,7 @@ void QMimeBinaryProvider::loadIcon(QMimeTypePrivate &data)
     checkCache();
     const QByteArray inputMime = data.name.toLatin1();
     for (CacheFile *cacheFile : qAsConst(m_cacheFiles)) {
-        const QString icon = iconForMime(cacheFile, PosIconsListOffset, inputMime);
+        const QLatin1String icon = iconForMime(cacheFile, PosIconsListOffset, inputMime);
         if (!icon.isEmpty()) {
             data.iconName = icon;
             return;
@@ -697,7 +697,7 @@ void QMimeBinaryProvider::loadGenericIcon(QMimeTypePrivate &data)
     checkCache();
     const QByteArray inputMime = data.name.toLatin1();
     for (CacheFile *cacheFile : qAsConst(m_cacheFiles)) {
-        const QString icon = iconForMime(cacheFile, PosGenericIconsListOffset, inputMime);
+        const QLatin1String icon = iconForMime(cacheFile, PosGenericIconsListOffset, inputMime);
         if (!icon.isEmpty()) {
             data.genericIconName = icon;
             return;
diff --git a/src/corelib/mimetypes/qmimeprovider_p.h b/src/corelib/mimetypes/qmimeprovider_p.h
index f410e62267..0be01d2fd0 100644
--- a/src/corelib/mimetypes/qmimeprovider_p.h
+++ b/src/corelib/mimetypes/qmimeprovider_p.h
@@ -116,7 +116,7 @@ private:
     void matchGlobList(QMimeGlobMatchResult &result, CacheFile *cacheFile, int offset, const QString &fileName);
     bool matchSuffixTree(QMimeGlobMatchResult &result, CacheFile *cacheFile, int numEntries, int firstOffset, const QString &fileName, int charPos, bool caseSensitiveCheck);
     bool matchMagicRule(CacheFile *cacheFile, int numMatchlets, int firstOffset, const QByteArray &data);
-    QString iconForMime(CacheFile *cacheFile, int posListOffset, const QByteArray &inputMime);
+    QLatin1String iconForMime(CacheFile *cacheFile, int posListOffset, const QByteArray &inputMime);
     void loadMimeTypeList();
     void checkCache();