Add Q_FALLTHROUGH for Qt < 5.8

... and make use of it.
With gcc 7, the new option -Wimplicit-fallthrough is introduced and
added to the -Wextra set, triggering dozens of warnings in our sources.
Therefore, we annotate all obviously intended fall-throughs. The ones
that are still left are unclear and need to be checked by the respective
maintainer.

Change-Id: I44ead33cd42a4b41c28ee5fcb5a31db272710bbc
Reviewed-by: Nikita Baryshnikov <nib952051@gmail.com>
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/plugins/cpptools/compileroptionsbuilder.cpp b/src/plugins/cpptools/compileroptionsbuilder.cpp
index 8f5fd397fb..170279c9b8 100644
--- a/src/plugins/cpptools/compileroptionsbuilder.cpp
+++ b/src/plugins/cpptools/compileroptionsbuilder.cpp
@@ -26,6 +26,7 @@
 #include "compileroptionsbuilder.h"
 
 #include <projectexplorer/projectexplorerconstants.h>
+#include <utils/qtcfallthrough.h>
 
 #include <QDir>
 #include <QRegularExpression>
@@ -201,7 +202,8 @@ static QStringList createLanguageOptionGcc(ProjectFile::Kind fileKind, bool objc
         if (!objcExt) {
             opts += QLatin1String("c++-header");
             break;
-        } // else: fall-through!
+        }
+        Q_FALLTHROUGH();
     case ProjectFile::ObjCHeader:
     case ProjectFile::ObjCXXHeader:
         opts += QLatin1String("objective-c++-header");
@@ -211,7 +213,8 @@ static QStringList createLanguageOptionGcc(ProjectFile::Kind fileKind, bool objc
         if (!objcExt) {
             opts += QLatin1String("c");
             break;
-        } // else: fall-through!
+        }
+        Q_FALLTHROUGH();
     case ProjectFile::ObjCSource:
         opts += QLatin1String("objective-c");
         break;
@@ -220,7 +223,8 @@ static QStringList createLanguageOptionGcc(ProjectFile::Kind fileKind, bool objc
         if (!objcExt) {
             opts += QLatin1String("c++");
             break;
-        } // else: fall-through!
+        }
+        Q_FALLTHROUGH();
     case ProjectFile::ObjCXXSource:
         opts += QLatin1String("objective-c++");
         break;