Support C++17 fallthrough attribute

Replaces our mix of comments for annotating intended absence of break
in switches with the C++17 attribute [[fallthrough]], or its earlier
a clang extension counterpart.

Change-Id: I4b2d0b9b5e4425819c7f1bf01608093c536b6d14
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/src/corelib/kernel/qsystemerror.cpp b/src/corelib/kernel/qsystemerror.cpp
index f38daec4f8..3899f24d3b 100644
--- a/src/corelib/kernel/qsystemerror.cpp
+++ b/src/corelib/kernel/qsystemerror.cpp
@@ -149,12 +149,13 @@ QString QSystemError::toString() const
         return windowsErrorString(errorCode);
 #else
         //unix: fall through as native and standard library are the same
+        Q_FALLTHROUGH();
 #endif
     case StandardLibraryError:
         return standardLibraryErrorString(errorCode);
     default:
         qWarning("invalid error scope");
-        //fall through
+        Q_FALLTHROUGH();
     case NoError:
         return QLatin1String("No error");
     }