build: Pull in GCC warning infra from ostree

I'm trying to keep a relatively standard set around, and the code
there is cleaner than what we had before.

Also, injecting as WARN_CFLAGS rather than changing CFLAGS during
autoconf avoids any surprises from new warnings breaking autoconf
checks.

7 files changed, 318 insertions, 70 deletions

diff --git a/buildutil/attributes.m4 b/buildutil/attributes.m4
new file mode 100644
index 0000000..51ac88b
--- /dev/null
+++ b/buildutil/attributes.m4
@@ -0,0 +1,292 @@
+dnl Macros to check the presence of generic (non-typed) symbols.
+dnl Copyright (c) 2006-2008 Diego Pettenò <flameeyes@gmail.com>
+dnl Copyright (c) 2006-2008 xine project
+dnl Copyright (c) 2012 Lucas De Marchi <lucas.de.marchi@gmail.com>
+dnl
+dnl This program is free software; you can redistribute it and/or modify
+dnl it under the terms of the GNU General Public License as published by
+dnl the Free Software Foundation; either version 2, or (at your option)
+dnl any later version.
+dnl
+dnl This program is distributed in the hope that it will be useful,
+dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl GNU General Public License for more details.
+dnl
+dnl You should have received a copy of the GNU General Public License
+dnl along with this program; if not, write to the Free Software
+dnl Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+dnl 02110-1301, USA.
+dnl
+dnl As a special exception, the copyright owners of the
+dnl macro gives unlimited permission to copy, distribute and modify the
+dnl configure scripts that are the output of Autoconf when processing the
+dnl Macro. You need not follow the terms of the GNU General Public
+dnl License when using or distributing such scripts, even though portions
+dnl of the text of the Macro appear in them. The GNU General Public
+dnl License (GPL) does govern all other use of the material that
+dnl constitutes the Autoconf Macro.
+dnl
+dnl This special exception to the GPL applies to versions of the
+dnl Autoconf Macro released by this project. When you make and
+dnl distribute a modified version of the Autoconf Macro, you may extend
+dnl this special exception to the GPL to apply to your modified version as
+dnl well.
+
+dnl Check if FLAG in ENV-VAR is supported by compiler and append it
+dnl to WHERE-TO-APPEND variable. Note that we invert -Wno-* checks to
+dnl -W* as gcc cannot test for negated warnings. If a C snippet is passed,
+dnl use it, otherwise use a simple main() definition that just returns 0.
+dnl CC_CHECK_FLAG_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG], [C-SNIPPET])
+
+AC_DEFUN([CC_CHECK_FLAG_APPEND], [
+  AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
+                 AS_TR_SH([cc_cv_$2_$3]),
+          [eval "AS_TR_SH([cc_save_$2])='${$2}'"
+           eval "AS_TR_SH([$2])='${cc_save_$2} -Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
+           AC_LINK_IFELSE([AC_LANG_SOURCE(ifelse([$4], [],
+                                                 [int main(void) { return 0; } ],
+                                                 [$4]))],
+                          [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
+                          [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
+           eval "AS_TR_SH([$2])='$cc_save_$2'"])
+
+  AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
+        [eval "$1='${$1} $3'"])
+])
+
+dnl CC_CHECK_FLAGS_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG1 FLAG2], [C-SNIPPET])
+AC_DEFUN([CC_CHECK_FLAGS_APPEND], [
+  for flag in [$3]; do
+    CC_CHECK_FLAG_APPEND([$1], [$2], $flag, [$4])
+  done
+])
+
+dnl Check if the flag is supported by linker (cacheable)
+dnl CC_CHECK_LDFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
+
+AC_DEFUN([CC_CHECK_LDFLAGS], [
+  AC_CACHE_CHECK([if $CC supports $1 flag],
+    AS_TR_SH([cc_cv_ldflags_$1]),
+    [ac_save_LDFLAGS="$LDFLAGS"
+     LDFLAGS="$LDFLAGS $1"
+     AC_LINK_IFELSE([int main() { return 1; }],
+       [eval "AS_TR_SH([cc_cv_ldflags_$1])='yes'"],
+       [eval "AS_TR_SH([cc_cv_ldflags_$1])="])
+     LDFLAGS="$ac_save_LDFLAGS"
+    ])
+
+  AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes],
+    [$2], [$3])
+])
+
+dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for
+dnl the current linker to avoid undefined references in a shared object.
+AC_DEFUN([CC_NOUNDEFINED], [
+  dnl We check $host for which systems to enable this for.
+  AC_REQUIRE([AC_CANONICAL_HOST])
+
+  case $host in
+     dnl FreeBSD (et al.) does not complete linking for shared objects when pthreads
+     dnl are requested, as different implementations are present; to avoid problems
+     dnl use -Wl,-z,defs only for those platform not behaving this way.
+     *-freebsd* | *-openbsd*) ;;
+     *)
+        dnl First of all check for the --no-undefined variant of GNU ld. This allows
+        dnl for a much more readable command line, so that people can understand what
+        dnl it does without going to look for what the heck -z defs does.
+        for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
+           CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])
+           break
+        done
+     ;;
+  esac
+
+  AC_SUBST([LDFLAGS_NOUNDEFINED])
+])
+
+dnl Check for a -Werror flag or equivalent. -Werror is the GCC
+dnl and ICC flag that tells the compiler to treat all the warnings
+dnl as fatal. We usually need this option to make sure that some
+dnl constructs (like attributes) are not simply ignored.
+dnl
+dnl Other compilers don't support -Werror per se, but they support
+dnl an equivalent flag:
+dnl  - Sun Studio compiler supports -errwarn=%all
+AC_DEFUN([CC_CHECK_WERROR], [
+  AC_CACHE_CHECK(
+    [for $CC way to treat warnings as errors],
+    [cc_cv_werror],
+    [CC_CHECK_CFLAGS_SILENT([-Werror], [cc_cv_werror=-Werror],
+      [CC_CHECK_CFLAGS_SILENT([-errwarn=%all], [cc_cv_werror=-errwarn=%all])])
+    ])
+])
+
+AC_DEFUN([CC_CHECK_ATTRIBUTE], [
+  AC_REQUIRE([CC_CHECK_WERROR])
+  AC_CACHE_CHECK([if $CC supports __attribute__(( ifelse([$2], , [$1], [$2]) ))],
+    AS_TR_SH([cc_cv_attribute_$1]),
+    [ac_save_CFLAGS="$CFLAGS"
+     CFLAGS="$CFLAGS $cc_cv_werror"
+     AC_COMPILE_IFELSE([AC_LANG_SOURCE([$3])],
+       [eval "AS_TR_SH([cc_cv_attribute_$1])='yes'"],
+       [eval "AS_TR_SH([cc_cv_attribute_$1])='no'"])
+     CFLAGS="$ac_save_CFLAGS"
+    ])
+
+  AS_IF([eval test x$]AS_TR_SH([cc_cv_attribute_$1])[ = xyes],
+    [AC_DEFINE(
+       AS_TR_CPP([SUPPORT_ATTRIBUTE_$1]), 1,
+         [Define this if the compiler supports __attribute__(( ifelse([$2], , [$1], [$2]) ))]
+         )
+     $4],
+    [$5])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [
+  CC_CHECK_ATTRIBUTE(
+    [constructor],,
+    [void __attribute__((constructor)) ctor() { int a; }],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_FORMAT], [
+  CC_CHECK_ATTRIBUTE(
+    [format], [format(printf, n, n)],
+    [void __attribute__((format(printf, 1, 2))) printflike(const char *fmt, ...) { fmt = (void *)0; }],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [
+  CC_CHECK_ATTRIBUTE(
+    [format_arg], [format_arg(printf)],
+    [char *__attribute__((format_arg(1))) gettextlike(const char *fmt) { fmt = (void *)0; }],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [
+  CC_CHECK_ATTRIBUTE(
+    [visibility_$1], [visibility("$1")],
+    [void __attribute__((visibility("$1"))) $1_function() { }],
+    [$2], [$3])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_NONNULL], [
+  CC_CHECK_ATTRIBUTE(
+    [nonnull], [nonnull()],
+    [void __attribute__((nonnull())) some_function(void *foo, void *bar) { foo = (void*)0; bar = (void*)0; }],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_UNUSED], [
+  CC_CHECK_ATTRIBUTE(
+    [unused], ,
+    [void some_function(void *foo, __attribute__((unused)) void *bar);],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [
+  CC_CHECK_ATTRIBUTE(
+    [sentinel], ,
+    [void some_function(void *foo, ...) __attribute__((sentinel));],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_DEPRECATED], [
+  CC_CHECK_ATTRIBUTE(
+    [deprecated], ,
+    [void some_function(void *foo, ...) __attribute__((deprecated));],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_ALIAS], [
+  CC_CHECK_ATTRIBUTE(
+    [alias], [weak, alias],
+    [void other_function(void *foo) { }
+     void some_function(void *foo) __attribute__((weak, alias("other_function")));],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_MALLOC], [
+  CC_CHECK_ATTRIBUTE(
+    [malloc], ,
+    [void * __attribute__((malloc)) my_alloc(int n);],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_PACKED], [
+  CC_CHECK_ATTRIBUTE(
+    [packed], ,
+    [struct astructure { char a; int b; long c; void *d; } __attribute__((packed));],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_CONST], [
+  CC_CHECK_ATTRIBUTE(
+    [const], ,
+    [int __attribute__((const)) twopow(int n) { return 1 << n; } ],
+    [$1], [$2])
+])
+
+AC_DEFUN([CC_FLAG_VISIBILITY], [
+  AC_REQUIRE([CC_CHECK_WERROR])
+  AC_CACHE_CHECK([if $CC supports -fvisibility=hidden],
+    [cc_cv_flag_visibility],
+    [cc_flag_visibility_save_CFLAGS="$CFLAGS"
+     CFLAGS="$CFLAGS $cc_cv_werror"
+     CC_CHECK_CFLAGS_SILENT([-fvisibility=hidden],
+     cc_cv_flag_visibility='yes',
+     cc_cv_flag_visibility='no')
+     CFLAGS="$cc_flag_visibility_save_CFLAGS"])
+
+  AS_IF([test "x$cc_cv_flag_visibility" = "xyes"],
+    [AC_DEFINE([SUPPORT_FLAG_VISIBILITY], 1,
+       [Define this if the compiler supports the -fvisibility flag])
+     $1],
+    [$2])
+])
+
+AC_DEFUN([CC_FUNC_EXPECT], [
+  AC_REQUIRE([CC_CHECK_WERROR])
+  AC_CACHE_CHECK([if compiler has __builtin_expect function],
+    [cc_cv_func_expect],
+    [ac_save_CFLAGS="$CFLAGS"
+     CFLAGS="$CFLAGS $cc_cv_werror"
+     AC_COMPILE_IFELSE([AC_LANG_SOURCE(
+       [int some_function() {
+        int a = 3;
+        return (int)__builtin_expect(a, 3);
+     }])],
+       [cc_cv_func_expect=yes],
+       [cc_cv_func_expect=no])
+     CFLAGS="$ac_save_CFLAGS"
+    ])
+
+  AS_IF([test "x$cc_cv_func_expect" = "xyes"],
+    [AC_DEFINE([SUPPORT__BUILTIN_EXPECT], 1,
+     [Define this if the compiler supports __builtin_expect() function])
+     $1],
+    [$2])
+])
+
+AC_DEFUN([CC_ATTRIBUTE_ALIGNED], [
+  AC_REQUIRE([CC_CHECK_WERROR])
+  AC_CACHE_CHECK([highest __attribute__ ((aligned ())) supported],
+    [cc_cv_attribute_aligned],
+    [ac_save_CFLAGS="$CFLAGS"
+     CFLAGS="$CFLAGS $cc_cv_werror"
+     for cc_attribute_align_try in 64 32 16 8 4 2; do
+        AC_COMPILE_IFELSE([AC_LANG_SOURCE([
+          int main() {
+            static char c __attribute__ ((aligned($cc_attribute_align_try))) = 0;
+            return c;
+          }])], [cc_cv_attribute_aligned=$cc_attribute_align_try; break])
+     done
+     CFLAGS="$ac_save_CFLAGS"
+  ])
+
+  if test "x$cc_cv_attribute_aligned" != "x"; then
+     AC_DEFINE_UNQUOTED([ATTRIBUTE_ALIGNED_MAX], [$cc_cv_attribute_aligned],
+       [Define the highest alignment supported])
+  fi
+])
diff --git a/configure.ac b/configure.ac
index f457a84..af2c8dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,6 +4,7 @@ AC_PREREQ(2.59c)
 AC_INIT([polkit], [0.114], [http://lists.freedesktop.org/mailman/listinfo/polkit-devel], , [http://www.freedesktop.org/wiki/Software/polkit])
 AM_INIT_AUTOMAKE([])
 AC_CONFIG_HEADERS(config.h)
+AC_CONFIG_MACRO_DIR([buildutil])
 AM_MAINTAINER_MODE
 
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
@@ -52,76 +53,26 @@ GTK_DOC_CHECK([1.3])
 
 #### gcc warning flags
 
-if test "x$GCC" = "xyes"; then
-  changequote(,)dnl
-  case " $CFLAGS " in
-  *[\ \	]-Wall[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wall" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wchar-subscripts[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wchar-subscripts" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wmissing-declarations[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wmissing-declarations" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wnested-externs[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wnested-externs" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wpointer-arith[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wpointer-arith" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wcast-align[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wcast-align" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wsign-compare[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wsign-compare" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wformat[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wformat" ;;
-  esac
-
-  case " $CFLAGS " in
-  *[\ \	]-Wformat-security[\ \	]*) ;;
-  *) CFLAGS="$CFLAGS -Wformat-security" ;;
-  esac
-
-  if test "x$enable_ansi" = "xyes"; then
-    case " $CFLAGS " in
-    *[\ \	]-ansi[\ \	]*) ;;
-    *) CFLAGS="$CFLAGS -ansi" ;;
-    esac
-
-    case " $CFLAGS " in
-    *[\ \	]-D_POSIX_C_SOURCE*) ;;
-    *) CFLAGS="$CFLAGS -D_POSIX_C_SOURCE=199309L" ;;
-    esac
-
-    case " $CFLAGS " in
-    *[\ \	]-D_BSD_SOURCE[\ \	]*) ;;
-    *) CFLAGS="$CFLAGS -D_BSD_SOURCE" ;;
-    esac
-
-    case " $CFLAGS " in
-    *[\ \	]-pedantic[\ \	]*) ;;
-    *) CFLAGS="$CFLAGS -pedantic" ;;
-    esac
-  fi
-  changequote([,])dnl
-fi
+CC_CHECK_FLAGS_APPEND([WARN_CFLAGS], [CFLAGS], [\
+        -pipe \
+        -Wall \
+	-Werror=empty-body \
+	-Werror=strict-prototypes \
+	-Werror=missing-prototypes \
+	-Werror=implicit-function-declaration \
+        "-Werror=format=2 -Werror=format-security -Werror=format-nonliteral" \
+	-Werror=pointer-arith -Werror=init-self \
+        -Werror=missing-declarations \
+        -Werror=return-type \
+        -Werror=overflow \
+        -Werror=int-conversion \
+        -Werror=parenthesis \
+        -Werror=incompatible-pointer-types \
+        -Werror=misleading-indentation \
+	-Werror=missing-include-dirs -Werror=aggregate-return \
+	-Werror=declaration-after-statement \
+])
+AC_SUBST(WARN_CFLAGS)
 
 PKG_CHECK_MODULES(GLIB, [gmodule-2.0 gio-unix-2.0 >= 2.30.0])
 AC_SUBST(GLIB_CFLAGS)
diff --git a/src/examples/Makefile.am b/src/examples/Makefile.am
index 71c4991..9b885f3 100644
--- a/src/examples/Makefile.am
+++ b/src/examples/Makefile.am
@@ -1,5 +1,6 @@
 
 NULL =
+AM_CFLAGS = -std=gnu99 $(WARN_CFLAGS)
 
 AM_CPPFLAGS =                                              	\
 	-I$(top_builddir)/src                           	\
diff --git a/src/polkit/Makefile.am b/src/polkit/Makefile.am
index 51befaf..ca36355 100644
--- a/src/polkit/Makefile.am
+++ b/src/polkit/Makefile.am
@@ -1,5 +1,6 @@
 NULL =
 
+AM_CFLAGS = -std=gnu99 $(WARN_CFLAGS)
 AM_CPPFLAGS =                                                   \
         -I$(top_builddir)/src                                   \
         -I$(top_srcdir)/src                                     \
diff --git a/src/polkitagent/Makefile.am b/src/polkitagent/Makefile.am
index 4b64165..49720db 100644
--- a/src/polkitagent/Makefile.am
+++ b/src/polkitagent/Makefile.am
@@ -1,5 +1,6 @@
 NULL =
 
+AM_CFLAGS = -std=gnu99 $(WARN_CFLAGS)
 AM_CPPFLAGS =                                                   \
         -I$(top_builddir)/src                                   \
         -I$(top_srcdir)/src                                     \
diff --git a/src/polkitbackend/Makefile.am b/src/polkitbackend/Makefile.am
index ca62474..e48b739 100644
--- a/src/polkitbackend/Makefile.am
+++ b/src/polkitbackend/Makefile.am
@@ -2,6 +2,7 @@ NULL =
 
 BUILT_SOURCES =
 
+AM_CFLAGS = -std=gnu99 $(WARN_CFLAGS)
 AM_CPPFLAGS =                                                   \
         -I$(top_builddir)/src                                   \
         -I$(top_srcdir)/src                                     \
diff --git a/src/programs/Makefile.am b/src/programs/Makefile.am
index 880b90b..d69853c 100644
--- a/src/programs/Makefile.am
+++ b/src/programs/Makefile.am
@@ -1,6 +1,7 @@
 
 NULL =
 
+AM_CFLAGS = -std=gnu99 $(WARN_CFLAGS)
 AM_CPPFLAGS =                                              	\
 	-I$(top_builddir)/src                           	\
 	-I$(top_srcdir)/src                             	\