suppress GCC7 fallthrough warnings

10 files changed, 94 insertions, 14 deletions

diff --git a/configure.ac b/configure.ac
index dfa4153..07d3568 100644
--- a/configure.ac
+++ b/configure.ac
@@ -34,6 +34,8 @@ AC_PROG_MAKE_SET
 LT_INIT([win32-dll disable-static pic-only])
 AC_CANONICAL_HOST
 
+DLP_FALLTHROUGH
+
 PKG_PROG_PKG_CONFIG([0.20])
 
 AM_MISSING_PROG([GPERF], [gperf])
diff --git a/m4/dlp_fallthrough.m4 b/m4/dlp_fallthrough.m4
new file mode 100644
index 0000000..99e6be5
--- /dev/null
+++ b/m4/dlp_fallthrough.m4
@@ -0,0 +1,65 @@
+#
+# SYNOPSIS
+#
+#   DLP_FALLTHROUGH
+#
+# DESCRIPTION
+#
+#   This macro checks if the compiler supports a fallthrough warning
+#   suppression attribute in GCC or CLANG style.
+#
+#   If a fallthrough warning suppression attribute is supported define
+#   HAVE_<STYLE>_ATTRIBUTE_FALLTHROUGH.
+#
+#   The macro caches its result in ax_cv_have_<style>_attribute_fallthrough
+#   variables.
+#
+# LICENSE
+#
+#   Copyright (c) 2017 David Tardon <dtardon@redhat.com>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 1
+
+m4_defun([_DLP_FALLTHROUGH], [
+    AS_VAR_PUSHDEF([ac_var], [ax_cv_have_$2_attribute_falltrough])
+
+    AC_CACHE_CHECK([for $1], [ac_var], [
+        AC_LINK_IFELSE([AC_LANG_PROGRAM([
+                void foo(int &i)
+                {
+                    switch (i)
+                    {
+                        case 0:
+                            i += 1;
+                            $1;
+                        default:
+                            i += 1;
+                    }
+                }
+            ], [])
+            ],
+            dnl GCC doesn't exit with an error if an unknown attribute is
+            dnl provided but only outputs a warning, so accept the attribute
+            dnl only if no warning were issued.
+            [AS_IF([test -s conftest.err],
+                [AS_VAR_SET([ac_var], [no])],
+                [AS_VAR_SET([ac_var], [yes])])],
+            [AS_VAR_SET([ac_var], [no])])
+    ])
+
+    AS_IF([test yes = AS_VAR_GET([ac_var])],
+        [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_$3_ATTRIBUTE_FALLTHROUGH), 1,
+            [Define to 1 if the system has the $4-style `fallthrough' attribute])], [])
+
+    AS_VAR_POPDEF([ac_var])
+])
+
+AC_DEFUN([DLP_FALLTHROUGH], [
+    _DLP_FALLTHROUGH([[__attribute__((fallthrough))]], [gcc], [GCC], [GNU])
+    _DLP_FALLTHROUGH([[[[clang:fallthrough]]]], [clang], [CLANG], [clang])
+])
diff --git a/src/lib/SW602Cell.cpp b/src/lib/SW602Cell.cpp
index 10ef0b2..3a0e5c8 100644
--- a/src/lib/SW602Cell.cpp
+++ b/src/lib/SW602Cell.cpp
@@ -171,12 +171,14 @@ bool SW602Cell::Format::convertDTFormat(std::string const &dtFormat, librevenge:
     {
     case 'Y':
       list.insert("number:style", "long");
+      SW602_FALLTHROUGH;
     case 'y':
       list.insert("librevenge:value-type", "year");
       propVect.append(list);
       break;
     case 'B':
       list.insert("number:style", "long");
+      SW602_FALLTHROUGH;
     case 'b':
     case 'h':
       list.insert("librevenge:value-type", "month");
@@ -189,13 +191,14 @@ bool SW602Cell::Format::convertDTFormat(std::string const &dtFormat, librevenge:
       break;
     case 'e':
       list.insert("number:style", "long");
-    // fall-through intended
+      SW602_FALLTHROUGH;
     case 'd':
       list.insert("librevenge:value-type", "day");
       propVect.append(list);
       break;
     case 'A':
       list.insert("number:style", "long");
+      SW602_FALLTHROUGH;
     case 'a':
       list.insert("librevenge:value-type", "day-of-week");
       propVect.append(list);
@@ -203,7 +206,7 @@ bool SW602Cell::Format::convertDTFormat(std::string const &dtFormat, librevenge:
 
     case 'H':
       list.insert("number:style", "long");
-    // fall-through intended
+      SW602_FALLTHROUGH;
     case 'I':
       list.insert("librevenge:value-type", "hours");
       propVect.append(list);
diff --git a/src/lib/SW602Chart.cpp b/src/lib/SW602Chart.cpp
index 8e7cf98..164f138 100644
--- a/src/lib/SW602Chart.cpp
+++ b/src/lib/SW602Chart.cpp
@@ -620,6 +620,7 @@ std::ostream &operator<<(std::ostream &o, SW602Chart::TextZone const &zone)
   {
   case SW602Chart::TextZone::T_SubTitle:
     o << "sub";
+    SW602_FALLTHROUGH;
   case SW602Chart::TextZone::T_Title:
     o << "title";
     if (zone.m_contentType==SW602Chart::TextZone::C_Cell)
diff --git a/src/lib/SW602GraphicListener.cpp b/src/lib/SW602GraphicListener.cpp
index 8a4930f..92dd406 100644
--- a/src/lib/SW602GraphicListener.cpp
+++ b/src/lib/SW602GraphicListener.cpp
@@ -1506,7 +1506,7 @@ void SW602GraphicListener::_handleFrameParameters(librevenge::RVNGPropertyList &
     {
     case SW602Position::YFull:
       list.insert("svg:height", double(h), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::YTop:
       if (origin[1] < 0.0 || origin[1] > 0.0)
       {
@@ -1550,7 +1550,7 @@ void SW602GraphicListener::_handleFrameParameters(librevenge::RVNGPropertyList &
     {
     case SW602Position::XFull:
       list.insert("svg:width", double(w), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::XLeft:
       if (origin[0] < 0.0 || origin[0] > 0.0)
       {
diff --git a/src/lib/SW602GraphicShape.cpp b/src/lib/SW602GraphicShape.cpp
index 0dee0b1..6adbf69 100644
--- a/src/lib/SW602GraphicShape.cpp
+++ b/src/lib/SW602GraphicShape.cpp
@@ -544,7 +544,7 @@ std::vector<SW602GraphicShape::PathData> SW602GraphicShape::getPath() const
   {
   case Measure:
     SW602_DEBUG_MSG(("SW602GraphicShape::getPath: called on a measure, transform it in line\n"));
-  // fall through expected
+    SW602_FALLTHROUGH;
   case Line:
   case Polygon:
   {
diff --git a/src/lib/SW602PageSpan.cpp b/src/lib/SW602PageSpan.cpp
index fae0fe9..c94b558 100644
--- a/src/lib/SW602PageSpan.cpp
+++ b/src/lib/SW602PageSpan.cpp
@@ -207,6 +207,7 @@ void SW602PageSpan::setHeaderFooter(SW602HeaderFooter const &hF)
   {
   case SW602HeaderFooter::NEVER:
     removeHeaderFooter(type, SW602HeaderFooter::ALL);
+    SW602_FALLTHROUGH;
   case SW602HeaderFooter::ALL:
     removeHeaderFooter(type, SW602HeaderFooter::ODD);
     removeHeaderFooter(type, SW602HeaderFooter::EVEN);
diff --git a/src/lib/SW602SpreadsheetListener.cpp b/src/lib/SW602SpreadsheetListener.cpp
index dcdfac3..3932926 100644
--- a/src/lib/SW602SpreadsheetListener.cpp
+++ b/src/lib/SW602SpreadsheetListener.cpp
@@ -1040,7 +1040,7 @@ void SW602SpreadsheetListener::insertShape
   case SW602Position::Unknown:
   default:
     SW602_DEBUG_MSG(("SW602SpreadsheetListener::insertShape: UNKNOWN position, insert as char position\n"));
-  // fallthrough intended
+    SW602_FALLTHROUGH;
   case SW602Position::CharBaseLine:
   case SW602Position::Char:
     if (m_ps->m_isSpanOpened)
@@ -1158,7 +1158,7 @@ bool SW602SpreadsheetListener::openFrame(SW602Position const &pos, SW602GraphicS
     break;
   case SW602Position::Unknown:
     SW602_DEBUG_MSG(("SW602SpreadsheetListener::openFrame: UNKNOWN position, insert as char position\n"));
-  // fallthrough intended
+    SW602_FALLTHROUGH;
   case SW602Position::CharBaseLine:
   case SW602Position::Char:
     if (m_ps->m_isSpanOpened)
@@ -1347,7 +1347,7 @@ void SW602SpreadsheetListener::_handleFrameParameters
     {
     case SW602Position::YFull:
       propList.insert("svg:height", double(h), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::YTop:
       if (origin[1] < 0.0 || origin[1] > 0.0)
       {
@@ -1391,7 +1391,7 @@ void SW602SpreadsheetListener::_handleFrameParameters
     {
     case SW602Position::XFull:
       propList.insert("svg:width", double(w), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::XLeft:
       if (origin[0] < 0.0 || origin[0] > 0.0)
       {
diff --git a/src/lib/SW602TextListener.cpp b/src/lib/SW602TextListener.cpp
index 4af4582..4d62d25 100644
--- a/src/lib/SW602TextListener.cpp
+++ b/src/lib/SW602TextListener.cpp
@@ -1125,7 +1125,7 @@ void SW602TextListener::insertShape
   case SW602Position::Unknown:
   default:
     SW602_DEBUG_MSG(("SW602TextListener::insertShape: UNKNOWN position, insert as char position\n"));
-  // fallthrough intended
+    SW602_FALLTHROUGH;
   case SW602Position::CharBaseLine:
   case SW602Position::Char:
     if (m_ps->m_isSpanOpened)
@@ -1246,7 +1246,7 @@ bool SW602TextListener::openFrame(SW602Position const &pos, SW602GraphicStyle co
     break;
   case SW602Position::Unknown:
     SW602_DEBUG_MSG(("SW602TextListener::openFrame: UNKNOWN position, insert as char position\n"));
-  // fallthrough intended
+    SW602_FALLTHROUGH;
   case SW602Position::CharBaseLine:
   case SW602Position::Char:
     if (m_ps->m_isSpanOpened)
@@ -1334,7 +1334,7 @@ bool SW602TextListener::openGroup(SW602Position const &pos)
   case SW602Position::Unknown:
   default:
     SW602_DEBUG_MSG(("SW602TextListener::openGroup: UNKNOWN position, insert as char position\n"));
-  // fallthrough intended
+    SW602_FALLTHROUGH;
   case SW602Position::CharBaseLine:
   case SW602Position::Char:
     if (m_ps->m_isSpanOpened)
@@ -1497,7 +1497,7 @@ void SW602TextListener::_handleFrameParameters
     {
     case SW602Position::YFull:
       propList.insert("svg:height", double(h), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::YTop:
       if (origin[1] < 0.0 || origin[1] > 0.0)
       {
@@ -1541,7 +1541,7 @@ void SW602TextListener::_handleFrameParameters
     {
     case SW602Position::XFull:
       propList.insert("svg:width", double(w), unit);
-    // fallthrough intended
+      SW602_FALLTHROUGH;
     case SW602Position::XLeft:
       if (origin[0] < 0.0 || origin[0] > 0.0)
       {
diff --git a/src/lib/libsw602_utils.h b/src/lib/libsw602_utils.h
index 380f08b..0d726d7 100644
--- a/src/lib/libsw602_utils.h
+++ b/src/lib/libsw602_utils.h
@@ -19,6 +19,14 @@
 #include <librevenge-stream/librevenge-stream.h>
 #include <librevenge/librevenge.h>
 
+#if defined(HAVE_CLANG_ATTRIBUTE_FALLTHROUGH)
+#  define SW602_FALLTHROUGH [[clang::fallthrough]]
+#elif defined(HAVE_GCC_ATTRIBUTE_FALLTHROUGH)
+#  define SW602_FALLTHROUGH __attribute__((fallthrough))
+#else
+#  define SW602_FALLTHROUGH ((void) 0)
+#endif
+
 namespace libsw602
 {
 }