Avoid some warnings from Sun C.

Some versions of Sun C support __attribute__ but don't support the
"unused" or "format" attributes - they don't fail, but they whine a lot.
They also support the "noreturn" attribute, but don't allow it to be
applied to function pointers, only to functions.

Check whether they can be used without warnings, and use them only if
they can.

1 files changed, 228 insertions, 1 deletions

diff --git a/configure b/configure
index 5fde04c9..a56eb7b0 100755
--- a/configure
+++ b/configure
@@ -2851,12 +2851,25 @@ echo "${ECHO_T}$ac_cv_lbl_gcc_vers" >&6; }
 			    V_CCOPT="-O2"
 		    fi
 	    fi
+
+	    #
+	    # -Werror forces warnings to be errors.
+	    #
+	    ac_lbl_cc_force_warning_errors=-Werror
     else
 	    V_INCLS="$V_INCLS -I/usr/local/include"
 	    LDFLAGS="$LDFLAGS -L/usr/local/lib"
 
 	    case "$host_os" in
 
+	    darwin*)
+		    #
+		    # This is assumed either to be GCC or clang, both
+		    # of which use -Werror to force warnings to be errors.
+		    #
+		    ac_lbl_cc_force_warning_errors=-Werror
+		    ;;
+
 	    hpux*)
 		    #
 		    # HP C, which is what we presume we're using, doesn't
@@ -2895,6 +2908,14 @@ echo "${ECHO_T}$ac_cv_lbl_gcc_vers" >&6; }
 		    V_CCOPT="$V_CCOPT -O"
 		    ;;
 
+	    solaris*)
+		    #
+		    # Assumed to be Sun C, which requires -errwarn to force
+		    # warnings to be treated as errors.
+		    #
+		    ac_lbl_cc_force_warning_errors=-errwarn
+		    ;;
+
 	    ultrix*)
 		    { echo "$as_me:$LINENO: checking that Ultrix $CC hacks const in prototypes" >&5
 echo $ECHO_N "checking that Ultrix $CC hacks const in prototypes... $ECHO_C" >&6; }
@@ -3113,8 +3134,11 @@ cat >>confdefs.h <<\_ACEOF
 #define HAVE___ATTRIBUTE__ 1
 _ACEOF
 
-  V_DEFS="$V_DEFS -D_U_=\"__attribute__((unused))\""
 else
+  #
+  # We can't use __attribute__, so we can't use __attribute__((unused)),
+  # so we define _U_ to an empty string.
+  #
   V_DEFS="$V_DEFS -D_U_=\"\""
 fi
 { echo "$as_me:$LINENO: result: $ac_cv___attribute__" >&5
@@ -3122,6 +3146,208 @@ echo "${ECHO_T}$ac_cv___attribute__" >&6; }
 
 if test "$ac_cv___attribute__" = "yes"; then
 
+{ echo "$as_me:$LINENO: checking whether __attribute__((unused)) can be used without warnings" >&5
+echo $ECHO_N "checking whether __attribute__((unused)) can be used without warnings... $ECHO_C" >&6; }
+if test "${ac_cv___attribute___unused+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors"
+cat >conftest.$ac_ext <<_ACEOF
+
+  /* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+int
+main(int argc  __attribute((unused)), char **argv __attribute((unused)))
+{
+  printf("Hello, world!\n");
+  return 0;
+}
+
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv___attribute___unused=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv___attribute___unused=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+CFLAGS="$save_CFLAGS"
+if test "$ac_cv___attribute___unused" = "yes"; then
+  V_DEFS="$V_DEFS -D_U_=\"__attribute__((unused))\""
+else
+  V_DEFS="$V_DEFS -D_U_=\"\""
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv___attribute___unused" >&5
+echo "${ECHO_T}$ac_cv___attribute___unused" >&6; }
+
+
+{ echo "$as_me:$LINENO: checking whether __attribute__((noreturn)) can be applied to function pointers without warnings" >&5
+echo $ECHO_N "checking whether __attribute__((noreturn)) can be applied to function pointers without warnings... $ECHO_C" >&6; }
+if test "${ac_cv___attribute___noreturn_function_pointer+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors"
+cat >conftest.$ac_ext <<_ACEOF
+
+  /* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+
+extern int (*foo)(int i)
+		  __attribute__ ((noreturn));
+
+int
+main(int argc, char **argv)
+{
+  (*foo)(1);
+}
+
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv___attribute___noreturn_function_pointer=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv___attribute___noreturn_function_pointer=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+CFLAGS="$save_CFLAGS"
+if test "$ac_cv___attribute___noreturn_function_pointer" = "yes"; then
+
+cat >>confdefs.h <<\_ACEOF
+#define __ATTRIBUTE___NORETURN_OK_FOR_FUNCTION_POINTERS 1
+_ACEOF
+
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv___attribute___noreturn_function_pointer" >&5
+echo "${ECHO_T}$ac_cv___attribute___noreturn_function_pointer" >&6; }
+
+
+{ echo "$as_me:$LINENO: checking whether __attribute__((format)) can be used without warnings" >&5
+echo $ECHO_N "checking whether __attribute__((format)) can be used without warnings... $ECHO_C" >&6; }
+if test "${ac_cv___attribute___format+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+
+save_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS $ac_lbl_cc_force_warning_errors"
+cat >conftest.$ac_ext <<_ACEOF
+
+  /* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <stdlib.h>
+
+extern int foo(const char *fmt, ...)
+		  __attribute__ ((format (printf, 1, 2)));
+
+int
+main(int argc, char **argv)
+{
+  foo("%s", "test");
+}
+
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  ac_cv___attribute___format=yes
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv___attribute___format=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+
+CFLAGS="$save_CFLAGS"
+if test "$ac_cv___attribute___format" = "yes"; then
+
+cat >>confdefs.h <<\_ACEOF
+#define __ATTRIBUTE___FORMAT_OK 1
+_ACEOF
+
+fi
+{ echo "$as_me:$LINENO: result: $ac_cv___attribute___format" >&5
+echo "${ECHO_T}$ac_cv___attribute___format" >&6; }
+
+	if test "$ac_cv___attribute___format" = "yes"; then
+
 { echo "$as_me:$LINENO: checking whether __attribute__((format)) can be applied to function pointers" >&5
 echo $ECHO_N "checking whether __attribute__((format)) can be applied to function pointers... $ECHO_C" >&6; }
 if test "${ac_cv___attribute___format_function_pointer+set}" = set; then
@@ -3186,6 +3412,7 @@ fi
 { echo "$as_me:$LINENO: result: $ac_cv___attribute___format_function_pointer" >&5
 echo "${ECHO_T}$ac_cv___attribute___format_function_pointer" >&6; }
 
+	fi
 fi
 ac_ext=c
 ac_cpp='$CPP $CPPFLAGS'