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>

4 files changed, 13 insertions, 14 deletions

diff --git a/src/widgets/styles/qcommonstyle.cpp b/src/widgets/styles/qcommonstyle.cpp
index 6cdfc061e1..140f0ad2f3 100644
--- a/src/widgets/styles/qcommonstyle.cpp
+++ b/src/widgets/styles/qcommonstyle.cpp
@@ -4232,7 +4232,6 @@ QRect QCommonStyle::subControlRect(ComplexControl cc, const QStyleOptionComplex
         if (const QStyleOptionGroupBox *groupBox = qstyleoption_cast<const QStyleOptionGroupBox *>(opt)) {
             switch (sc) {
             case SC_GroupBoxFrame:
-                // FALL THROUGH
             case SC_GroupBoxContents: {
                 int topMargin = 0;
                 int topHeight = 0;
@@ -4261,7 +4260,6 @@ QRect QCommonStyle::subControlRect(ComplexControl cc, const QStyleOptionComplex
                 break;
             }
             case SC_GroupBoxCheckBox:
-                // FALL THROUGH
             case SC_GroupBoxLabel: {
                 QFontMetrics fontMetrics = groupBox->fontMetrics;
                 int h = fontMetrics.height();
@@ -4327,7 +4325,7 @@ QRect QCommonStyle::subControlRect(ComplexControl cc, const QStyleOptionComplex
             if (numSubControls == 1)
                 break;
             offset += buttonWidth + 2;
-            //FALL THROUGH
+            Q_FALLTHROUGH();
         case SC_MdiNormalButton:
             // No offset needed if
             // 1) There's only one sub control
@@ -4895,7 +4893,7 @@ QSize QCommonStyle::sizeFromContents(ContentsType ct, const QStyleOption *opt,
     case CT_ProgressBar:
     case CT_TabBarTab:
         // just return the contentsSize for now
-        // fall through intended
+        Q_FALLTHROUGH();
     default:
         break;
     }
diff --git a/src/widgets/styles/qstylesheetstyle.cpp b/src/widgets/styles/qstylesheetstyle.cpp
index 44555c3058..c5904a5a96 100644
--- a/src/widgets/styles/qstylesheetstyle.cpp
+++ b/src/widgets/styles/qstylesheetstyle.cpp
@@ -1100,7 +1100,7 @@ void QRenderRule::fixupBorder(int nativeWidth)
             case BorderStyle_Native:
                 if (bd->borders[i] == 0)
                     bd->borders[i] = nativeWidth;
-                // intentional fall through
+                Q_FALLTHROUGH();
             default:
                 if (bd->colors[i].style() == Qt::NoBrush) // auto-acquire 'color'
                     bd->colors[i] = color;
diff --git a/src/widgets/styles/qwindowsstyle.cpp b/src/widgets/styles/qwindowsstyle.cpp
index c3a50968e2..e3bf28608c 100644
--- a/src/widgets/styles/qwindowsstyle.cpp
+++ b/src/widgets/styles/qwindowsstyle.cpp
@@ -808,7 +808,8 @@ void QWindowsStyle::drawPrimitive(PrimitiveElement pe, const QStyleOption *opt,
             p->setPen(opt->palette.dark().color());
         else
             p->setPen(opt->palette.text().color());
-        } // Fall through!
+        }
+        Q_FALLTHROUGH();
     case PE_IndicatorViewItemCheck:
         if (!doRestore) {
             p->save();
@@ -2383,7 +2384,7 @@ QSize QWindowsStyle::sizeFromContents(ContentsType ct, const QStyleOption *opt,
     case CT_ToolButton:
         if (qstyleoption_cast<const QStyleOptionToolButton *>(opt))
             return sz += QSize(7, 6);
-        // Otherwise, fall through
+        Q_FALLTHROUGH();
 
     default:
         sz = QCommonStyle::sizeFromContents(ct, opt, csz, widget);
diff --git a/src/widgets/styles/qwindowsxpstyle.cpp b/src/widgets/styles/qwindowsxpstyle.cpp
index ffedc37edb..f3a8544d96 100644
--- a/src/widgets/styles/qwindowsxpstyle.cpp
+++ b/src/widgets/styles/qwindowsxpstyle.cpp
@@ -3465,13 +3465,13 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
             case SC_TitleBarContextHelpButton:
                 if (tb->titleBarFlags & Qt::WindowContextHelpButtonHint)
                     offset += delta;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarMinButton:
                 if (!isMinimized && (tb->titleBarFlags & Qt::WindowMinimizeButtonHint))
                     offset += delta;
                 else if (subControl == SC_TitleBarMinButton)
                     break;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarNormalButton:
                 if (isMinimized && (tb->titleBarFlags & Qt::WindowMinimizeButtonHint))
                     offset += delta;
@@ -3479,25 +3479,25 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
                     offset += delta;
                 else if (subControl == SC_TitleBarNormalButton)
                     break;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarMaxButton:
                 if (!isMaximized && (tb->titleBarFlags & Qt::WindowMaximizeButtonHint))
                     offset += delta;
                 else if (subControl == SC_TitleBarMaxButton)
                     break;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarShadeButton:
                 if (!isMinimized && (tb->titleBarFlags & Qt::WindowShadeButtonHint))
                     offset += delta;
                 else if (subControl == SC_TitleBarShadeButton)
                     break;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarUnshadeButton:
                 if (isMinimized && (tb->titleBarFlags & Qt::WindowShadeButtonHint))
                     offset += delta;
                 else if (subControl == SC_TitleBarUnshadeButton)
                     break;
-                //fall through
+                Q_FALLTHROUGH();
             case SC_TitleBarCloseButton:
                 if (tb->titleBarFlags & Qt::WindowSystemMenuHint)
                     offset += delta;
@@ -3576,7 +3576,7 @@ QRect QWindowsXPStyle::subControlRect(ComplexControl cc, const QStyleOptionCompl
             if (numSubControls == 1)
                 break;
             offset += buttonWidth;
-            //FALL THROUGH
+            Q_FALLTHROUGH();
         case SC_MdiNormalButton:
             // No offset needed if
             // 1) There's only one sub control