Pass non-trivial/large function args by reference

Fixes a bunch of `-Wclazy-function-args-by-ref` warnings. See
https://github.com/KDE/clazy/blob/master/docs/checks/README-function-args-by-ref.md
for details.

Most of these changes are automated, using the clazy fixit by setting
the `CLAZY_EXPORT_FIXES` before compilation and then running:

    $ mkdir /tmp/patch
    $ find ../src -iname "*.yaml" -exec mv {} /tmp/patch \;
    $ clang-apply-replacements /tmp/patch

7 files changed, 16 insertions, 15 deletions

diff --git a/src/skin/colorschemeparser.cpp b/src/skin/colorschemeparser.cpp
index c750e66f8b..ce0a221d00 100644
--- a/src/skin/colorschemeparser.cpp
+++ b/src/skin/colorschemeparser.cpp
@@ -13,10 +13,10 @@
 #include "skin/legacyskinparser.h"
 #include "skin/skincontext.h"
 
-void ColorSchemeParser::setupLegacyColorSchemes(QDomElement docElem,
-                                                UserSettingsPointer pConfig,
-                                                QString* pStyle,
-                                                SkinContext* pContext) {
+void ColorSchemeParser::setupLegacyColorSchemes(const QDomElement& docElem,
+        UserSettingsPointer pConfig,
+        QString* pStyle,
+        SkinContext* pContext) {
     QDomNode schemesNode = docElem.namedItem("Schemes");
 
     bool bSelectedColorSchemeFound = false;
@@ -71,7 +71,7 @@ void ColorSchemeParser::setupLegacyColorSchemes(QDomElement docElem,
     }
 }
 
-ImgSource* ColorSchemeParser::parseFilters(QDomNode filt) {
+ImgSource* ColorSchemeParser::parseFilters(const QDomNode& filt) {
     ImgSource* ret = new ImgLoader();
 
     if (!filt.hasChildNodes()) {
diff --git a/src/skin/colorschemeparser.h b/src/skin/colorschemeparser.h
index 61f63d188b..6decd79a92 100644
--- a/src/skin/colorschemeparser.h
+++ b/src/skin/colorschemeparser.h
@@ -10,12 +10,13 @@ class ImgSource;
 class ColorSchemeParser {
   public:
     static void setupLegacyColorSchemes(
-            QDomElement docElem,
+            const QDomElement& docElem,
             UserSettingsPointer pConfig,
             QString* pStyle,
             SkinContext* pContext);
+
   private:
-    static ImgSource* parseFilters(QDomNode filter);
+    static ImgSource* parseFilters(const QDomNode& filter);
     ColorSchemeParser() { }
     ~ColorSchemeParser() { }
 };
diff --git a/src/skin/skincontext.h b/src/skin/skincontext.h
index d89e7d9205..044878f3f4 100644
--- a/src/skin/skincontext.h
+++ b/src/skin/skincontext.h
@@ -239,11 +239,11 @@ class SkinContext {
 
     QDebug logWarning(const char* file, const int line, const QDomNode& node) const;
 
-    void defineSingleton(QString objectName, QWidget* widget) {
+    void defineSingleton(const QString& objectName, QWidget* widget) {
         return m_pSharedState->singletons.insertSingleton(objectName, widget);
     }
 
-    QWidget* getSingletonWidget(QString objectName) const {
+    QWidget* getSingletonWidget(const QString& objectName) const {
         return m_pSharedState->singletons.getSingletonWidget(objectName);
     }
 
diff --git a/src/skin/skinloader.cpp b/src/skin/skinloader.cpp
index abc5a45db0..2cd7e9f5fb 100644
--- a/src/skin/skinloader.cpp
+++ b/src/skin/skinloader.cpp
@@ -145,7 +145,7 @@ LaunchImage* SkinLoader::loadLaunchImage(QWidget* pParent) {
     return pLaunchImage;
 }
 
-QString SkinLoader::pickResizableSkin(QString oldSkin) const {
+QString SkinLoader::pickResizableSkin(const QString& oldSkin) const {
     if (oldSkin.contains("latenight", Qt::CaseInsensitive)) {
         return "LateNight";
     }
diff --git a/src/skin/skinloader.h b/src/skin/skinloader.h
index 2892ce903c..9b3796508f 100644
--- a/src/skin/skinloader.h
+++ b/src/skin/skinloader.h
@@ -41,7 +41,7 @@ class SkinLoader {
     QList<QDir> getSkinSearchPaths() const;
 
   private:
-    QString pickResizableSkin(QString oldSkin) const;
+    QString pickResizableSkin(const QString& oldSkin) const;
 
     UserSettingsPointer m_pConfig;
 };
diff --git a/src/skin/tooltips.cpp b/src/skin/tooltips.cpp
index bb4be75bdd..87cbd48918 100644
--- a/src/skin/tooltips.cpp
+++ b/src/skin/tooltips.cpp
@@ -7,7 +7,7 @@ Tooltips::Tooltips() {
 Tooltips::~Tooltips() {
 }
 
-QString Tooltips::tooltipForId(QString id) const {
+QString Tooltips::tooltipForId(const QString& id) const {
     // We always add a separator at the end.
     QString joined = m_tooltips.value(id, QStringList()).join(tooltipSeparator());
     if (joined.length() > 0) {
@@ -20,7 +20,7 @@ QString Tooltips::tooltipSeparator() const {
     return "\n";
 }
 
-QList<QString>& Tooltips::add(QString id) {
+QList<QString>& Tooltips::add(const QString& id) {
     return m_tooltips[id];
 }
 
diff --git a/src/skin/tooltips.h b/src/skin/tooltips.h
index fdbfbc8308..35b2fc05ec 100644
--- a/src/skin/tooltips.h
+++ b/src/skin/tooltips.h
@@ -10,12 +10,12 @@ class Tooltips : public QObject {
   public:
     Tooltips();
     virtual ~Tooltips();
-    QString tooltipForId(QString id) const;
+    QString tooltipForId(const QString& id) const;
 
   private:
     void addStandardTooltips();
     QString tooltipSeparator() const;
-    QList<QString>& add(QString id);
+    QList<QString>& add(const QString& id);
 
     QHash<QString, QStringList> m_tooltips;
 };