make configure test which flags gcc actually accepts ...

git-svn-id: svn://svn.oetiker.ch/rrdtool/branches/1.2/program@830 a5681a0c-68f1-0310-ab6d-d61299d08faa

diff --git a/configure.ac b/configure.ac
index 3818b05c7795e98fe56266b4ff0c33f138b88969..94ec225383bba79a3014a8803f9826cecc47ba2f 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -189,6 +189,21 @@ AC_PROG_CC
 AC_PROG_CPP
 AC_PROG_LIBTOOL
 
+dnl which flags does the compile support?
+if test "$GCC" = "yes"; then
+  for flag in -fno-strict-aliasing -Wall -std=gnu99 -pedantic -Wshadow -Wpointer-arith -Wcast-align -Wmissing-prototypes -Wmissing-declarations -Wnested-externs -Winline -W; do
+    oCFLAGS=$CFLAGS
+    CFLAGS="$CFLAGS $flag"
+    cachename=rd_cv_gcc_flag_`echo $flag|sed 's/[[^A-Za-z]]/_/g'`
+    AC_CACHE_CHECK([if gcc likes the $flag flag], $cachename,
+       [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[return 0 ]])],[eval $cachename=yes],[eval $cachename=no])])
+    if eval test \$$cachename = no; then
+         CFLAGS=$oCFLAGS
+    fi
+  done
+fi
+
+
 
 AC_SUBST(RRD_DEFAULT_FONT)
 
@@ -527,19 +542,6 @@ AC_ARG_VAR(RRDDOCDIR, [[DATADIR/doc/PACKAGE-VERSION] Documentation directory])
 if test -z "$RRDDOCDIR"; then
    RRDDOCDIR='${datadir}/doc/${PACKAGE}-${VERSION}'; fi
 
-dnl Does the compiler like -Wall and -pedantic?
-if test "$GCC" = "yes"; then
-  oCFLAGS=$CFLAGS
-  CFLAGS="$CFLAGS -fno-strict-aliasing -Wall -std=gnu99 -pedantic -Wshadow -Wpointer-arith -Wcast-align -Wmissing-prototypes -Wmissing-declarations -Wnested-externs -Winline -W"
-  AC_CACHE_CHECK(if we can use GCC-specific compiler options, rd_cv_gcc_opt,
-                [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[]], [[return 0 ]])],[rd_cv_gcc_opt=yes],[rd_cv_gcc_opt=no ])
-               ]
-        )
-  if test $rd_cv_gcc_opt = no; then
-         CFLAGS=$oCFLAGS
-  fi
-fi
-
 
 CONFIGURE_PART(Apply Configuration Information)