[Libreoffice-commits] libcdr.git: configure.ac m4/dlp_fallthrough.m4 src/lib

[David Tardon]

 configure.ac           |    1 
 m4/dlp_fallthrough.m4  |   65 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/lib/CMXParser.cpp  |    2 -
 src/lib/libcdr_utils.h |    8 ++++++
 4 files changed, 75 insertions(+), 1 deletion(-)

New commits:
commit 0e23de6ce871a646f9e1f33b8b5ea90e30eb9e95
Author: David Tardon <dtardon at redhat.com>
Date:   Sat Jul 29 17:02:25 2017 +0200

    suppress GCC 7 fallthrough warning
    
    Change-Id: I6a1da60f75130e897191f20910aab9a3a46b5b57

diff --git a/configure.ac b/configure.ac
index 78b34f4..39770dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -35,6 +35,7 @@ AC_CANONICAL_HOST
 
 AX_CXX_COMPILE_STDCXX_11
 AX_GCC_FUNC_ATTRIBUTE([format])
+DLP_FALLTHROUGH
 
 PKG_PROG_PKG_CONFIG([0.20])
 
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 at 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/CMXParser.cpp b/src/lib/CMXParser.cpp
index 5abc4f0..de0344e 100644
--- a/src/lib/CMXParser.cpp
+++ b/src/lib/CMXParser.cpp
@@ -2297,7 +2297,7 @@ libcdr::CDRColor libcdr::CMXParser::readColor(librevenge::RVNGInputStream *input
   }
   case 0xff: // something funny here
     input->seek(4, librevenge::RVNG_SEEK_CUR);
-  // Fallthrough intended
+    CDR_FALLTHROUGH;
   default:
     CDR_DEBUG_MSG(("Unknown color model %i\n", colorModel));
     break;
diff --git a/src/lib/libcdr_utils.h b/src/lib/libcdr_utils.h
index c9c0ec6..b1d0b9f 100644
--- a/src/lib/libcdr_utils.h
+++ b/src/lib/libcdr_utils.h
@@ -36,6 +36,14 @@
 #  define CDR_ATTRIBUTE_PRINTF(fmt, arg)
 #endif
 
+#if defined(HAVE_CLANG_ATTRIBUTE_FALLTHROUGH)
+#  define CDR_FALLTHROUGH [[clang::fallthrough]]
+#elif defined(HAVE_GCC_ATTRIBUTE_FALLTHROUGH)
+#  define CDR_FALLTHROUGH __attribute__((fallthrough))
+#else
+#  define CDR_FALLTHROUGH ((void) 0)
+#endif
+
 // do nothing with debug messages in a release compile
 #ifdef DEBUG
 namespace libcdr