diff --git a/src/dolphincontextmenu.cpp b/src/dolphincontextmenu.cpp
--- a/src/dolphincontextmenu.cpp
+++ b/src/dolphincontextmenu.cpp
@@ -431,6 +431,7 @@
 
 bool DolphinContextMenu::placeExists(const QUrl& url) const
 {
+    Q_UNUSED(url)
     // Creating up a PlacesItemModel to find out if 'url' is one of the Places
     // can be expensive because the model asks Solid for the devices which are
     // available, which can take some time.
diff --git a/src/dolphinmainwindow.cpp b/src/dolphinmainwindow.cpp
--- a/src/dolphinmainwindow.cpp
+++ b/src/dolphinmainwindow.cpp
@@ -411,6 +411,8 @@
             case QDialogButtonBox::No:
                 // Close only the current tab
                 m_tabWidget->closeTab();
+                // Do not quit, ignore quit event
+                // fall through
             default:
                 event->ignore();
                 return;
diff --git a/src/dolphintabwidget.cpp b/src/dolphintabwidget.cpp
--- a/src/dolphintabwidget.cpp
+++ b/src/dolphintabwidget.cpp
@@ -91,7 +91,10 @@
         } else {
             // Tab state created with Dolphin <= 4.14.x
             const QByteArray state = group.readEntry("Tab " % QString::number(i), QByteArray());
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
             tabPageAt(i)->restoreStateV1(state);
+#pragma GCC diagnostic pop
         }
     }
 
diff --git a/src/kitemviews/kfileitemmodel.cpp b/src/kitemviews/kfileitemmodel.cpp
--- a/src/kitemviews/kfileitemmodel.cpp
+++ b/src/kitemviews/kfileitemmodel.cpp
@@ -248,7 +248,6 @@
     // Copyright (C) 2006 David Faure <faure@kde.org>
     QList<QUrl> urls;
     QList<QUrl> mostLocalUrls;
-    bool canUseMostLocalUrls = true;
     const ItemData* lastAddedItem = nullptr;
 
     for (int index : indexes) {
@@ -271,9 +270,6 @@
 
             bool isLocal;
             mostLocalUrls << item.mostLocalUrl(isLocal);
-            if (!isLocal) {
-                canUseMostLocalUrls = false;
-            }
         }
     }
 
diff --git a/src/kitemviews/kitemlistcontroller.cpp b/src/kitemviews/kitemlistcontroller.cpp
--- a/src/kitemviews/kitemlistcontroller.cpp
+++ b/src/kitemviews/kitemlistcontroller.cpp
@@ -435,8 +435,8 @@
                 }
             }
         }
-        // Fall through to the default case and add the Space to the current search string.
-
+        // fall through
+        // to the default case and add the Space to the current search string.
     default:
         m_keyboardManager->addKeys(event->text());
         // Make sure unconsumed events get propagated up the chain. #302329
diff --git a/src/panels/information/phononwidget.cpp b/src/panels/information/phononwidget.cpp
--- a/src/panels/information/phononwidget.cpp
+++ b/src/panels/information/phononwidget.cpp
@@ -23,7 +23,10 @@
 #include <Phonon/AudioOutput>
 #include <Phonon/MediaObject>
 #include <Phonon/SeekSlider>
+#pragma GCC diagnostic push                          // Phonon doesn't use C++11 compiler by default, so override
+#pragma GCC diagnostic ignored "-Wsuggest-override"  // specifier is not available. Remove this pragmas after fixing it.
 #include <Phonon/VideoWidget>
+#pragma GCC diagnostic pop
 
 #include <QVBoxLayout>
 #include <QShowEvent>