- Check for --as-needed linking flag

git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@318 3ecf2c5c-341e-0410-92b4-d18e462d057c

configure.ac

@@ -63,6 +63,7 @@ AC_PROG_CXX
 AC_CHECK_CXXFLAG([Wall])
 AC_CHECK_CXXFLAG([pedantic])
 AC_CHECK_CXXFLAG([Wextra])
+AC_CHECK_LDFLAG([--as-needed])
 
 AC_PROG_INSTALL
 

m4/Makefile.am

@@ -23,6 +23,7 @@
 # better if we don't install our macros...
 # -> aclocal_DATA = ...
 macros = compilerflags.m4 \
+	linkingflags.m4 \
 	ac_python_devel.m4 \
 	ac_pkg_swig.m4 \
 	ac_python_module.m4

m4/linkingflags.m4

@@ -0,0 +1,26 @@
+dnl  **************************************************
+dnl    Copyright (C) 2004   Matteo Settenvini
+dnl  **************************************************
+
+dnl ---------- AX_CHECK_LDFLAG ---------------------
+dnl This macro checks if a particular flag for the 
+dnl C++ compiler works. If it is so, it adds the flag 
+dnl to the CXXFLAGS variable. 
+dnl Example of usage : AC_CHECK_LDFLAG([--as-needed])
+dnl -------------------------------------------------
+AC_DEFUN([AC_CHECK_LDFLAG],
+[ AC_REQUIRE([AC_PROG_CC])dnl
+  AC_MSG_CHECKING([whether the linker supports the $1 flag])
+  ac_check_ldflags=$LDFLAGS
+  LDFLAGS="-Wl,$1"
+  AC_LANG_PUSH([C])
+  AC_LINK_IFELSE(
+    AC_LANG_PROGRAM([], [return 0;]),
+    [AC_MSG_RESULT([yes])
+      LDFLAGS="-Wl,$1 $ac_check_ldflags" ],
+    [AC_MSG_RESULT([no])
+      LDFLAGS=$ac_check_ldflags ]
+  )
+  AC_LANG_POP
+])dnl ------- AC_CHECK_LDFLAG ----------------------
+