[network-manager-libreswan: 9/11] build: update m4 macros and add --enable-lto and --enable-ld-gc



commit 56405f1e9b01e4be16b3d5a5bb72a64fbc866aa1
Author: Thomas Haller <thaller redhat com>
Date:   Fri Feb 24 18:25:06 2017 +0100

    build: update m4 macros and add --enable-lto and --enable-ld-gc
    
    - add support for --enable-lto and --enable-ld-gc
    - enable -Wextra warnings

 configure.ac           |    9 ++
 m4/attributes.m4       |  292 ++++++++++++++++++++++++++++++++++++++++++++++++
 m4/compiler_options.m4 |   63 +++++++++--
 3 files changed, 356 insertions(+), 8 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 3dc753f..d6c7d33 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,6 +14,10 @@ AC_CONFIG_HEADERS([config.h])
 
 AC_USE_SYSTEM_EXTENSIONS
 
+dnl Prefer gcc-* variants; the ones libtool would choose don't work with LTO
+AC_CHECK_TOOLS(AR, [gcc-ar ar], false)
+AC_CHECK_TOOLS(RANLIB, [gcc-ranlib ranlib], :)
+
 dnl
 dnl Require programs
 dnl
@@ -139,6 +143,8 @@ NM_VPN_SERVICE_DIR=`$PKG_CONFIG --define-variable prefix='\${prefix}' --variable
 AC_SUBST(NM_VPN_SERVICE_DIR)
 
 NM_COMPILER_WARNINGS([yes])
+NM_LTO
+NM_LD_GC
 
 NM_PLUGIN_DIR="$libdir/NetworkManager"
 AC_SUBST(NM_PLUGIN_DIR)
@@ -172,3 +178,6 @@ echo "  --enable-absolute-paths=$enable_absolute_paths"
 echo "  --enable-more-warnings=$set_more_warnings"
 echo "  --with-nm-ipsec-conf=$with_nm_ipsec_conf"
 echo "  --with-nm-ipsec-secrets-dir=$with_nm_ipsec_secrets_dir"
+echo "  --enable-lto=$enable_lto"
+echo "  --enable-ld-gc=$enable_ld_gc"
+echo ""
diff --git a/m4/attributes.m4 b/m4/attributes.m4
new file mode 100644
index 0000000..51ac88b
--- /dev/null
+++ b/m4/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/m4/compiler_options.m4 b/m4/compiler_options.m4
index 0023c36..5275281 100644
--- a/m4/compiler_options.m4
+++ b/m4/compiler_options.m4
@@ -61,16 +61,31 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
                CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror"
        fi
 
-       for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \
-                     -Wdeclaration-after-statement -Wformat-security \
-                     -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare \
-                     -Wno-duplicate-decl-specifier \
+       for option in \
+                     -Wextra \
+                     -Wdeclaration-after-statement \
+                     -Wfloat-equal \
+                     -Wformat-nonliteral \
+                     -Wformat-security \
+                     -Wimplicit-fallthrough \
+                     -Wimplicit-function-declaration \
+                     -Winit-self \
+                     -Wmissing-declarations \
+                     -Wmissing-include-dirs \
+                     -Wmissing-prototypes \
+                     -Wpointer-arith \
+                     -Wshadow \
                      -Wstrict-prototypes \
-                     -Wno-unused-but-set-variable \
+                     -Wundef \
+                     -Wno-duplicate-decl-specifier \
+                     -Wno-format-truncation \
                      -Wno-format-y2k \
-                     -Wundef -Wimplicit-function-declaration \
-                     -Wpointer-arith -Winit-self -Wformat-nonliteral \
-                     -Wmissing-include-dirs -Wno-pragmas; do
+                     -Wno-missing-field-initializers \
+                     -Wno-pragmas \
+                     -Wno-sign-compare \
+                     -Wno-unused-but-set-variable \
+                     -Wno-unused-parameter \
+                     ; do
                dnl GCC 4.4 does not warn when checking for -Wno-* flags 
(https://gcc.gnu.org/wiki/FAQ#wnowarning)
                 _NM_COMPILER_FLAG([$(printf '%s' "$option" | sed 's/^-Wno-/-W/')], [],
                                  [CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS $option"], [])
@@ -109,3 +124,35 @@ else
        AC_MSG_RESULT(no)
 fi
 ])
+
+AC_DEFUN([NM_LTO],
+[AC_ARG_ENABLE(lto, AS_HELP_STRING([--enable-lto], [Enable Link Time Optimization for smaller size (default: 
no)]))
+if (test "${enable_lto}" = "yes"); then
+       CC_CHECK_FLAG_APPEND([lto_flags], [CFLAGS], [-flto])
+       if (test -n "${lto_flags}"); then
+               CFLAGS="-flto $CFLAGS"
+       else
+               AC_MSG_ERROR([Link Time Optimization -flto is not supported.])
+       fi
+else
+       enable_lto='no'
+fi
+])
+
+AC_DEFUN([NM_LD_GC],
+[AC_ARG_ENABLE(ld-gc, AS_HELP_STRING([--enable-ld-gc], [Enable garbage collection of unused symbols on 
linking (default: auto)]))
+if (test "${enable_ld_gc}" != "no"); then
+       CC_CHECK_FLAG_APPEND([ld_gc_flags], [CFLAGS], [-fdata-sections -ffunction-sections -Wl,--gc-sections])
+       if (test -n "${ld_gc_flags}"); then
+               enable_ld_gc="yes"
+               CFLAGS="$ld_gc_flags $CFLAGS"
+       else
+               if (test "${enable_ld_gc}" = "yes"); then
+                       AC_MSG_ERROR([Unused symbol eviction requested but not supported.])
+               else
+                       enable_ld_gc="no"
+               fi
+       fi
+fi
+])
+


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