Merge remote branch 'flameeyes/noundefined'

3 files changed, 57 insertions, 6 deletions

diff --git a/configure.ac b/configure.ac
index a185464..38b7701 100644
--- a/configure.ac
+++ b/configure.ac
@@ -44,11 +44,7 @@ AC_USE_SYSTEM_EXTENSIONS
 AC_PROG_MAKE_SET
 AC_PROG_LIBTOOL
 
-DESIRED_FLAGS="-Wall -W -Wextra -pedantic -pipe -Wformat -Wold-style-definition -Wdeclaration-after-statement -Wfloat-equal -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wredundant-decls -Wmissing-noreturn -Wshadow -Wendif-labels -Wpointer-arith -Wcast-align -Wwrite-strings -Winline -Wno-unused-parameter -ffast-math"
-
-for flag in $DESIRED_FLAGS ; do
-  CC_CHECK_CFLAGS([$flag], [CFLAGS="$CFLAGS $flag"])
-done
+CC_CHECK_CFLAGS_APPEND([-Wall -W -Wextra -pedantic -pipe -Wformat -Wold-style-definition -Wdeclaration-after-statement -Wfloat-equal -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wredundant-decls -Wmissing-noreturn -Wshadow -Wendif-labels -Wpointer-arith -Wcast-align -Wwrite-strings -Winline -Wno-unused-parameter -ffast-math])
 
 # Checks for header files.
 AC_HEADER_ASSERT
@@ -74,6 +70,8 @@ AC_TYPE_SIZE_T
 
 AC_SYS_LARGEFILE
 
+CC_NOUNDEFINED
+
 ZP_LYNX_DOC
 
 AC_ARG_ENABLE(examples,
diff --git a/libdaemon/Makefile.am b/libdaemon/Makefile.am
index 11a5305..220006a 100644
--- a/libdaemon/Makefile.am
+++ b/libdaemon/Makefile.am
@@ -39,4 +39,4 @@ libdaemon_la_SOURCES = \
 	daemon.h \
 	$(pkg_include_HEADERS)
 
-libdaemon_la_LDFLAGS = -version-info $(LIBDAEMON_VERSION_INFO)
+libdaemon_la_LDFLAGS = -version-info $(LIBDAEMON_VERSION_INFO) $(LDFLAGS_NOUNDEFINED)
diff --git a/m4/attributes.m4 b/m4/attributes.m4
index 9c4a0c8..e86456a 100644
--- a/m4/attributes.m4
+++ b/m4/attributes.m4
@@ -32,6 +32,9 @@ 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 the flag is supported by compiler
+dnl CC_CHECK_CFLAGS_SILENT([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
+
 AC_DEFUN([CC_CHECK_CFLAGS_SILENT], [
   AC_CACHE_VAL(AS_TR_SH([cc_cv_cflags_$1]),
     [ac_save_CFLAGS="$CFLAGS"
@@ -46,6 +49,9 @@ AC_DEFUN([CC_CHECK_CFLAGS_SILENT], [
     [$2], [$3])
 ])
 
+dnl Check if the flag is supported by compiler (cacheable)
+dnl CC_CHECK_CFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
+
 AC_DEFUN([CC_CHECK_CFLAGS], [
   AC_CACHE_CHECK([if $CC supports $1 flag],
     AS_TR_SH([cc_cv_cflags_$1]),
@@ -56,6 +62,28 @@ AC_DEFUN([CC_CHECK_CFLAGS], [
     [$2], [$3])
 ])
 
+dnl CC_CHECK_CFLAG_APPEND(FLAG, [action-if-found], [action-if-not-found])
+dnl Check for CFLAG and appends them to CFLAGS if supported
+AC_DEFUN([CC_CHECK_CFLAG_APPEND], [
+  AC_CACHE_CHECK([if $CC supports $1 flag],
+    AS_TR_SH([cc_cv_cflags_$1]),
+    CC_CHECK_CFLAGS_SILENT([$1]) dnl Don't execute actions here!
+  )
+
+  AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes],
+    [CFLAGS="$CFLAGS $1"; $2], [$3])
+])
+
+dnl CC_CHECK_CFLAGS_APPEND([FLAG1 FLAG2], [action-if-found], [action-if-not])
+AC_DEFUN([CC_CHECK_CFLAGS_APPEND], [
+  for flag in $1; do
+    CC_CHECK_CFLAG_APPEND($flag, [$2], [$3])
+  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]),
@@ -71,6 +99,31 @@ AC_DEFUN([CC_CHECK_LDFLAGS], [
     [$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 $host in
+     dnl FreeBSD (et al.) does not complete linking for shared objects when pthreads
+     dnl are requested, as different implementations are present; to avoid problems
+     dnl use -Wl,-z,defs only for those platform not behaving this way.
+     *-freebsd*) ;;
+     *)
+        dnl First of all check for the --no-undefined variant of GNU ld. This allows
+        dnl for a much more readable commandline, so that people can understand what
+        dnl it does without going to look for what the heck -z defs does.
+   	for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
+          CC_CHECK_LDFLAGS([$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