1 files changed, 61 insertions, 0 deletions
diff --git a/m4/ccstdc.m4 b/m4/ccstdc.m4
new file mode 100644
index 000000000..727fea1f0
--- /dev/null
+++ b/m4/ccstdc.m4
@@ -0,0 +1,61 @@
+## ----------------------------------------- ##
+## ANSIfy the C compiler whenever possible.  ##
+## From Franc,ois Pinard                     ##
+## ----------------------------------------- ##
+
+# serial 1
+
+# @defmac AC_PROG_CC_STDC
+# @maindex PROG_CC_STDC
+# @ovindex CC
+# If the C compiler in not in ANSI C mode by default, try to add an option
+# to output variable @code{CC} to make it so.  This macro tries various
+# options that select ANSI C on some system or another.  It considers the
+# compiler to be in ANSI C mode if it defines @code{__STDC__} to 1 and
+# handles function prototypes correctly.
+#
+# If you use this macro, you should check after calling it whether the C
+# compiler has been set to accept ANSI C; if not, the shell variable
+# @code{am_cv_prog_cc_stdc} is set to @samp{no}.  If you wrote your source
+# code in ANSI C, you can make an un-ANSIfied copy of it by using the
+# program @code{ansi2knr}, which comes with Ghostscript.
+# @end defmac
+
+AC_DEFUN(AM_PROG_CC_STDC,
+[AC_REQUIRE([AC_PROG_CC])
+AC_MSG_CHECKING(for ${CC-cc} option to accept ANSI C)
+AC_CACHE_VAL(am_cv_prog_cc_stdc,
+[am_cv_prog_cc_stdc=no
+ac_save_CC="$CC"
+# Don't try gcc -ansi; that turns off useful extensions and
+# breaks some systems' header files.
+# AIX			-qlanglvl=ansi
+# Ultrix and OSF/1	-std1
+# HP-UX			-Aa -D_HPUX_SOURCE
+# SVR4			-Xc -D__EXTENSIONS__
+for ac_arg in "" -qlanglvl=ansi -std1 "-Aa -D_HPUX_SOURCE" "-Xc -D__EXTENSIONS__"
+do
+  CC="$ac_save_CC $ac_arg"
+  AC_TRY_COMPILE(
+[#if !defined(__STDC__) || __STDC__ != 1
+choke me
+#endif
+/* DYNIX/ptx V4.1.3 can't compile sys/stat.h with -Xc -D__EXTENSIONS__. */
+#ifdef _SEQUENT_
+# include <sys/types.h>
+# include <sys/stat.h>
+#endif
+], [
+int test (int i, double x);
+struct s1 {int (*f) (int a);};
+struct s2 {int (*f) (double a);};],
+[am_cv_prog_cc_stdc="$ac_arg"; break])
+done
+CC="$ac_save_CC"
+])
+AC_MSG_RESULT($am_cv_prog_cc_stdc)
+case "x$am_cv_prog_cc_stdc" in
+  x|xno) ;;
+  *) CC="$CC $am_cv_prog_cc_stdc" ;;
+esac
+])