Test for the availability of -Wextra not understood by gcc 3.3

diff --git a/configure.in b/configure.in
index 34bd3d739d320fd3d7ad092fb833bd2794b43537..e64fbc87ce074ba2cafe6b04f06d92fde7a9c4b4 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -20,11 +20,20 @@ esac
 if test "${CC}" = "cc" ; then
    CFLAGS="${CFLAGS} -g -O2 -Aa"
 fi
-CFLAGS="${CFLAGS} -Wall -Wextra -Wno-sign-compare -Wno-unused-parameter"
+CFLAGS="${CFLAGS} -Wall -Wno-sign-compare -Wno-unused-parameter"
 
-dnl Check for supported gcc options
+dnl Check for supported compiler options
 
-AC_MSG_CHECKING([for implicit-function-declaration error flag in gcc])
+AC_MSG_CHECKING([for extra warnings flag in $CC])
+saved_CFLAGS="${CFLAGS}"
+CFLAGS="${CFLAGS} -Wextra"
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_extra_warnings="yes"],[have_extra_warnings="no"])
+AC_MSG_RESULT($have_extra_warnings)
+if test "$have_extra_warnings" == "no" ; then
+    CFLAGS="${saved_CFLAGS}"
+fi
+
+AC_MSG_CHECKING([for implicit-function-declaration error flag in $CC])
 saved_CFLAGS="${CFLAGS}"
 CFLAGS="${CFLAGS} -Werror=implicit-function-declaration"
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_implicit_function_declaration="yes"],[have_implicit_function_declaration="no"])
@@ -33,7 +42,7 @@ if test "$have_implicit_function_declaration" == "no" ; then
     CFLAGS="${saved_CFLAGS}"
 fi
 
-AC_MSG_CHECKING([for format error flag in gcc])
+AC_MSG_CHECKING([for format error flag in $CC])
 saved_CFLAGS="${CFLAGS}"
 CFLAGS="${CFLAGS} -Werror=format"
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_error_format="yes"],[have_error_format="no"])
@@ -207,7 +216,7 @@ AC_ARG_ENABLE(extraprotection,
           CFLAGS="${CFLAGS} -Werror"
        fi
 
-       AC_MSG_CHECKING([for format security flag in gcc])
+       AC_MSG_CHECKING([for format security flag in $CC])
        saved_CFLAGS="${CFLAGS}"
        CFLAGS="${CFLAGS} -Wformat -Werror=format-security"
        AC_COMPILE_IFELSE([AC_LANG_SOURCE([])],[have_format_security="yes"],[have_format_security="no"])