Imported Upstream version 1.0.0upstream/1.0.0

2 files changed, 40 insertions, 8 deletions

diff --git a/m4/ax_lib_readline.m4 b/m4/ax_lib_readline.m4
index 72764fba5..fe56c5bfc 100644
--- a/m4/ax_lib_readline.m4
+++ b/m4/ax_lib_readline.m4
@@ -90,8 +90,11 @@ AC_DEFUN([AX_LIB_READLINE], [
     AC_MSG_ERROR([readline library with terminfo support is required (one of ncurses, curses, or termcap)])
   fi
 
+  ORIG_LIBS="$LIBS"
   LIBS="$LIBS $ax_cv_lib_readline"
   AC_CHECK_HEADERS(readline.h readline/readline.h)
+
+  # Check history
   AC_CACHE_CHECK([whether readline supports history],
                  ax_cv_lib_readline_history, [
     ax_cv_lib_readline_history="no"
@@ -101,6 +104,18 @@ AC_DEFUN([AX_LIB_READLINE], [
     AC_MSG_ERROR(readline history support is required)
   fi
   AC_CHECK_HEADERS(history.h readline/history.h)
+
+  # check rl_echo_signal_char()
+  AC_CACHE_CHECK([whether readline supports rl_echo_signal_char()],
+                 ax_cv_lib_readline_echo_signal_char, [
+    ax_cv_lib_readline_echo_signal_char="no"
+    AC_TRY_LINK_FUNC(rl_echo_signal_char, ax_cv_lib_readline_echo_signal_char="yes")
+  ])
+  if test "$ax_cv_lib_readline_echo_signal_char" != "yes"; then
+    AC_MSG_ERROR(rl_echo_signal_char() is required (install readline6?))
+  fi
+
+  LIBS="$ORIG_LIBS"
   READLINE_LIBS="$ax_cv_lib_readline"
   AC_SUBST(READLINE_LIBS)
 ])dnl
diff --git a/m4/compiler_warnings.m4 b/m4/compiler_warnings.m4
index 357ff0e7e..c05a26d09 100644
--- a/m4/compiler_warnings.m4
+++ b/m4/compiler_warnings.m4
@@ -5,32 +5,49 @@ AC_DEFUN([NM_COMPILER_WARNINGS],
 AC_MSG_CHECKING(for more warnings)
 if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
 	AC_MSG_RESULT(yes)
-	CFLAGS="-Wall -std=gnu89 $CFLAGS"
+	CFLAGS_SAVED="$CFLAGS"
+	CFLAGS_MORE_WARNINGS="-Wall -std=gnu89"
+
+	dnl clang only warns about unknown warnings, unless
+	dnl called with "-Werror=unknown-warning-option"
+	dnl Test if the compiler supports that, and if it does
+	dnl attach it to the CFLAGS.
+	CFLAGS_EXTRA="-Werror=unknown-warning-option"
+	CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $CFLAGS_SAVED"
+	AC_TRY_COMPILE([], [],
+		has_option=yes,
+		has_option=no,)
+	if test $has_option = no; then
+		CFLAGS_EXTRA=
+	fi
+	unset has_option
 
 	for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \
 		      -Wdeclaration-after-statement -Wformat-security \
 		      -Wfloat-equal -Wno-unused-parameter -Wno-sign-compare \
+		      -Wstrict-prototypes \
 		      -fno-strict-aliasing -Wno-unused-but-set-variable \
 		      -Wundef -Wimplicit-function-declaration \
 		      -Wpointer-arith -Winit-self \
-		      -Wmissing-include-dirs -Waggregate-return; do
-		SAVE_CFLAGS="$CFLAGS"
-		CFLAGS="$CFLAGS $option"
+		      -Wmissing-include-dirs; do
+		CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_EXTRA $option $CFLAGS_SAVED"
 		AC_MSG_CHECKING([whether gcc understands $option])
 		AC_TRY_COMPILE([], [],
 			has_option=yes,
 			has_option=no,)
-		if test $has_option = no; then
-			CFLAGS="$SAVE_CFLAGS"
+		if test $has_option != no; then
+			CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS $option"
 		fi
 		AC_MSG_RESULT($has_option)
 		unset has_option
-		unset SAVE_CFLAGS
 	done
 	unset option
+	unset CFLAGS_EXTRA
 	if test "x$set_more_warnings" = xerror; then
-		CFLAGS="$CFLAGS -Werror"
+		CFLAGS_MORE_WARNINGS="$CFLAGS_MORE_WARNINGS -Werror"
 	fi
+	CFLAGS="$CFLAGS_MORE_WARNINGS $CFLAGS_SAVED"
+	unset CFLAGS_SAVED
 else
 	AC_MSG_RESULT(no)
 fi