Merge pull request #257 from protobuf-c/edmonds/strict-warnings

Add warning flags to my_CFLAGS

configure.ac

@@ -24,6 +24,32 @@ LT_INIT
 AC_CONFIG_HEADERS(config.h)
 AC_CONFIG_FILES([Makefile protobuf-c/libprotobuf-c.pc])
 
+my_CFLAGS="\
+-Wall \
+-Wchar-subscripts \
+-Wdeclaration-after-statement \
+-Wformat-security \
+-Wmissing-declarations \
+-Wmissing-prototypes \
+-Wnested-externs \
+-Wpointer-arith \
+-Wshadow \
+-Wsign-compare \
+-Wstrict-prototypes \
+-Wtype-limits \
+"
+#AX_CHECK_COMPILE_FLAG(["-Wc90-c99-compat"],
+#                      [my_CFLAGS="$my_CFLAGS -Wc90-c99-compat"])
+AX_CHECK_COMPILE_FLAG(["-Wc99-c11-compat"],
+                      [my_CFLAGS="$my_CFLAGS -Wc99-c11-compat"])
+AX_CHECK_COMPILE_FLAG(["-Werror=incompatible-pointer-types"],
+                      [my_CFLAGS="$my_CFLAGS -Werror=incompatible-pointer-types"])
+AX_CHECK_COMPILE_FLAG(["-Werror=int-conversion"],
+                      [my_CFLAGS="$my_CFLAGS -Werror=int-conversion"])
+AX_CHECK_COMPILE_FLAG(["-Wnull-dereference"],
+                      [my_CFLAGS="$my_CFLAGS -Wnull-dereference"])
+AC_SUBST([my_CFLAGS])
+
 AC_CHECK_PROGS([DOXYGEN], [doxygen])
 AM_CONDITIONAL([HAVE_DOXYGEN],
                [test -n "$DOXYGEN"])

m4/ax_check_compile_flag.m4

@@ -0,0 +1,74 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_check_compile_flag.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_CHECK_COMPILE_FLAG(FLAG, [ACTION-SUCCESS], [ACTION-FAILURE], [EXTRA-FLAGS], [INPUT])
+#
+# DESCRIPTION
+#
+#   Check whether the given FLAG works with the current language's compiler
+#   or gives an error.  (Warnings, however, are ignored)
+#
+#   ACTION-SUCCESS/ACTION-FAILURE are shell commands to execute on
+#   success/failure.
+#
+#   If EXTRA-FLAGS is defined, it is added to the current language's default
+#   flags (e.g. CFLAGS) when the check is done.  The check is thus made with
+#   the flags: "CFLAGS EXTRA-FLAGS FLAG".  This can for example be used to
+#   force the compiler to issue an error when a bad flag is given.
+#
+#   INPUT gives an alternative input source to AC_COMPILE_IFELSE.
+#
+#   NOTE: Implementation based on AX_CFLAGS_GCC_OPTION. Please keep this
+#   macro in sync with AX_CHECK_{PREPROC,LINK}_FLAG.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Guido U. Draheim <guidod@gmx.de>
+#   Copyright (c) 2011 Maarten Bosmans <mkbosmans@gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <https://www.gnu.org/licenses/>.
+#
+#   As a special exception, the respective Autoconf Macro's copyright owner
+#   gives unlimited permission to copy, distribute and modify the configure
+#   scripts that are the output of Autoconf when processing the Macro. You
+#   need not follow the terms of the GNU General Public License when using
+#   or distributing such scripts, even though portions of the text of the
+#   Macro appear in them. The GNU General Public License (GPL) does govern
+#   all other use of the material that constitutes the Autoconf Macro.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf Archive. When you make and distribute a
+#   modified version of the Autoconf Macro, you may extend this special
+#   exception to the GPL to apply to your modified version as well.
+
+#serial 5
+
+AC_DEFUN([AX_CHECK_COMPILE_FLAG],
+[AC_PREREQ(2.64)dnl for _AC_LANG_PREFIX and AS_VAR_IF
+AS_VAR_PUSHDEF([CACHEVAR],[ax_cv_check_[]_AC_LANG_ABBREV[]flags_$4_$1])dnl
+AC_CACHE_CHECK([whether _AC_LANG compiler accepts $1], CACHEVAR, [
+  ax_check_save_flags=$[]_AC_LANG_PREFIX[]FLAGS
+  _AC_LANG_PREFIX[]FLAGS="$[]_AC_LANG_PREFIX[]FLAGS $4 $1"
+  AC_COMPILE_IFELSE([m4_default([$5],[AC_LANG_PROGRAM()])],
+    [AS_VAR_SET(CACHEVAR,[yes])],
+    [AS_VAR_SET(CACHEVAR,[no])])
+  _AC_LANG_PREFIX[]FLAGS=$ax_check_save_flags])
+AS_VAR_IF(CACHEVAR,yes,
+  [m4_default([$2], :)],
+  [m4_default([$3], :)])
+AS_VAR_POPDEF([CACHEVAR])dnl
+])dnl AX_CHECK_COMPILE_FLAGS

protobuf-c/protobuf-c.c

@@ -3213,7 +3213,6 @@ protobuf_c_message_unpack(const ProtobufCMessageDescriptor *desc,
 		unsigned max = (i_slab == which_slab) ?
 			in_slab_index : (1UL << (i_slab + 4));
 		ScannedMember *slab = scanned_member_slabs[i_slab];
-		unsigned j;
 
 		for (j = 0; j < max; j++) {
 			if (!parse_member(slab + j, rv, allocator)) {