KIconLoader: prefer icons from current theme before falling back to other themes

BUG: 445804

autotests/kiconloader_unittest.cpp

@@ -112,6 +112,12 @@ private Q_SLOTS:
         QVERIFY(QFile::copy(QStringLiteral(":/test-22x22.png"), testIconsDir.filePath(QStringLiteral("breeze/22x22/mimetypes/unknown.png"))));
         QVERIFY(QFile::copy(QStringLiteral(":/coloredsvgicon.svg"), testIconsDir.filePath(QStringLiteral("breeze/22x22/apps/coloredsvgicon.svg"))));
 
+        // prepare some icons for our actions test
+        // when querying breeze for 'one-two', we expect
+        // 'one' from breeze instead of oxygen's 'one-two'.
+        QVERIFY(QFile::copy(QStringLiteral(":/test-22x22.png"), testIconsDir.filePath(QStringLiteral("oxygen/22x22/actions/one-two.png"))));
+        QVERIFY(QFile::copy(QStringLiteral(":/test-22x22.png"), testIconsDir.filePath(QStringLiteral("breeze/22x22/actions/one.png"))));
+
         QVERIFY(QFile::setPermissions(breezeThemeFile, QFileDevice::ReadOwner | QFileDevice::WriteOwner));
         KConfig configFile(breezeThemeFile);
         KConfigGroup iconThemeGroup = configFile.group("Icon Theme");
@@ -332,6 +338,25 @@ private Q_SLOTS:
         QVERIFY(QFile::exists(unknownPath));
     }
 
+    void testCorrectFallback()
+    {
+        // we want to prefer icons from the same theme
+
+        // so if we have something like:
+        /*
+            oxygen:
+                one-two
+
+            breeze:
+                one
+        */
+        // and we ask for 'one-two', we expect to see 'one' from breeze instead
+        // of 'one-two' from oxygen.
+        QString path;
+        KIconLoader::global()->loadIcon(QStringLiteral("one-two"), KIconLoader::Desktop, 24, KIconLoader::DefaultState, QStringList(), &path);
+        QVERIFY(path.contains("breeze/22x22/actions"));
+    }
+
     void testPathStore()
     {
         QString path;

src/kiconloader.cpp

@@ -1021,12 +1021,7 @@ QString KIconLoaderPrivate::findMatchingIcon(const QString &name, int size, qrea
 {
     const_cast<KIconLoaderPrivate *>(this)->initIconThemes();
 
-    // Do two passes through themeNodes.
-    //
-    // The first pass looks for an exact match in each themeNode one after the other.
-    // If one is found and it is an app icon then return that icon.
-    //
-    // In the next pass (assuming the first pass failed), it looks for
+    // This looks for the exact match and its
     // generic fallbacks in each themeNode one after the other.
 
     // In theory we should only do this for mimetype icons, not for app icons,
@@ -1036,22 +1031,17 @@ QString KIconLoaderPrivate::findMatchingIcon(const QString &name, int size, qrea
     // Once everyone uses that to look up mimetype icons, we can kill the fallback code
     // from this method.
 
-    for (KIconThemeNode *themeNode : std::as_const(links)) {
-        const QString path = themeNode->theme->iconPathByName(name, size, KIconLoader::MatchBest, scale);
-        if (!path.isEmpty()) {
-            return path;
-        }
-    }
-
-    if (name.endsWith(QLatin1String("-x-generic"))) {
-        return QString(); // no further fallback
-    }
-    bool genericFallback = false;
+    bool genericFallback = name.endsWith(QLatin1String("-x-generic"));;
     QString path;
     for (KIconThemeNode *themeNode : std::as_const(links)) {
         QString currentName = name;
 
         while (!currentName.isEmpty()) {
+            path = themeNode->theme->iconPathByName(currentName, size, KIconLoader::MatchBest, scale);
+            if (!path.isEmpty()) {
+                return path;
+            }
+
             if (genericFallback) {
                 // we already tested the base name
                 break;
@@ -1088,16 +1078,6 @@ QString KIconLoaderPrivate::findMatchingIcon(const QString &name, int size, qrea
                     break;
                 }
             }
-
-            if (currentName.isEmpty()) {
-                break;
-            }
-
-            // qCDebug(KICONTHEMES) << "Looking up" << currentName;
-            path = themeNode->theme->iconPathByName(currentName, size, KIconLoader::MatchBest, scale);
-            if (!path.isEmpty()) {
-                return path;
-            }
         }
     }