With .devel, use -W flags iff the compiler supports them.

Don't base the question of whether to use a particular -W flag on
whether we're compiling with GCC or not, and on which version of GCC
we're using; some compilers, such as clang, also support many of those
-W flags.  Base it on whether the compiler complains if we use it (which
means, for clang, that we have to force it to exit with a non-zero exit
status if it doesn't like a flag; otherwise, we'll specify it, and clang
will warn about it on every compile).

1 files changed, 396 insertions, 4 deletions

diff --git a/configure b/configure
index 20ba1c14..f7b49d81 100755
--- a/configure
+++ b/configure
@@ -11289,15 +11289,407 @@ rm -f os-proto.h
 	    V_CCOPT="$V_CCOPT ${LBL_CFLAGS}"
     fi
     if test -f .devel ; then
+
+	{ echo "$as_me:$LINENO: checking whether the compiler fails when given an unknown warning option" >&5
+echo $ECHO_N "checking whether the compiler fails when given an unknown warning option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS -Wxyzzy-this-will-never-succeed-xyzzy"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		#
+		# We're assuming this is clang, where
+		# -Werror=unknown-warning-option is the appropriate
+		# option to force the compiler to fail.
+		#
+		ac_lbl_unknown_warning_option_error="-Werror=unknown-warning-option"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+	CFLAGS="$save_CFLAGS"
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wall option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wall option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wall"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wall"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wmissing-prototypes option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wmissing-prototypes option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wmissing-prototypes"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wmissing-prototypes"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wstrict-prototypes option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wstrict-prototypes option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wstrict-prototypes"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wstrict-prototypes"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wwrite-strings option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wwrite-strings option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wwrite-strings"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wwrite-strings"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -Wpointer-arith option" >&5
+echo $ECHO_N "checking whether the compiler supports the -Wpointer-arith option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -Wpointer-arith"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -Wpointer-arith"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+
+	{ echo "$as_me:$LINENO: checking whether the compiler supports the -W option" >&5
+echo $ECHO_N "checking whether the compiler supports the -W option... $ECHO_C" >&6; }
+	save_CFLAGS="$CFLAGS"
+	CFLAGS="$CFLAGS $ac_lbl_unknown_warning_option_error -W"
+	cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+return 0
+  ;
+  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.$ac_objext; then
+
+		{ echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+		CFLAGS="$save_CFLAGS"
+		V_CCOPT="$V_CCOPT -W"
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+		{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+		CFLAGS="$save_CFLAGS"
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
 	    if test "$GCC" = yes ; then
 		    if test "${LBL_CFLAGS+set}" != set; then
 			    if test "$ac_cv_prog_cc_g" = yes ; then
 				    V_CCOPT="-g $V_CCOPT"
 			    fi
-			    V_CCOPT="$V_CCOPT -Wall"
-			    if test $ac_cv_lbl_gcc_vers -gt 1 ; then
-				    V_CCOPT="$V_CCOPT -Wmissing-prototypes -Wstrict-prototypes -Wwrite-strings -Wpointer-arith -W"
-			    fi
 		    fi
 	    else
 		    case "$host_os" in