Imported Upstream version 1.6

[debian/gzip] / m4 / warnings.m4

diff --git a/m4/warnings.m4 b/m4/warnings.m4
index 28b8294ef04d2bfe78415fae058e6bdbc7cda6c7..184873283bbc51b4c4e7330a922926bcd71e8723 100644 (file)
--- a/m4/warnings.m4
+++ b/m4/warnings.m4
@@ -1,5 +1,5 @@
-# warnings.m4 serial 7
-dnl Copyright (C) 2008-2012 Free Software Foundation, Inc.
+# warnings.m4 serial 8
+dnl Copyright (C) 2008-2013 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -27,7 +27,7 @@ AC_DEFUN([gl_COMPILER_OPTION_IF],
 AS_VAR_PUSHDEF([gl_Flags], [_AC_LANG_PREFIX[]FLAGS])dnl
 AC_CACHE_CHECK([whether _AC_LANG compiler handles $1], m4_defn([gl_Warn]), [
   gl_save_compiler_FLAGS="$gl_Flags"
-  gl_AS_VAR_APPEND(m4_defn([gl_Flags]), [" $1"])
+  gl_AS_VAR_APPEND(m4_defn([gl_Flags]), [" $gl_unknown_warnings_are_errors $1"])
   AC_COMPILE_IFELSE([m4_default([$4], [AC_LANG_PROGRAM([])])],
                     [AS_VAR_SET(gl_Warn, [yes])],
                     [AS_VAR_SET(gl_Warn, [no])])
@@ -38,6 +38,14 @@ AS_VAR_POPDEF([gl_Flags])dnl
 AS_VAR_POPDEF([gl_Warn])dnl
 ])
 
+# gl_UNKNOWN_WARNINGS_ARE_ERRORS
+# ------------------------------
+# Clang doesn't complain about unknown warning options unless one also
+# specifies -Wunknown-warning-option -Werror.  Detect this.
+AC_DEFUN([gl_UNKNOWN_WARNINGS_ARE_ERRORS],
+[gl_COMPILER_OPTION_IF([-Werror -Wunknown-warning-option],
+   [gl_unknown_warnings_are_errors='-Wunknown-warning-option -Werror'],
+   [gl_unknown_warnings_are_errors=])])
 
 # gl_WARN_ADD(OPTION, [VARIABLE = WARN_CFLAGS],
 #             [PROGRAM = AC_LANG_PROGRAM()])
@@ -47,7 +55,8 @@ AS_VAR_POPDEF([gl_Warn])dnl
 #
 # If VARIABLE is a variable name, AC_SUBST it.
 AC_DEFUN([gl_WARN_ADD],
-[gl_COMPILER_OPTION_IF([$1],
+[AC_REQUIRE([gl_UNKNOWN_WARNINGS_ARE_ERRORS])
+gl_COMPILER_OPTION_IF([$1],
   [gl_AS_VAR_APPEND(m4_if([$2], [], [[WARN_CFLAGS]], [[$2]]), [" $1"])],
   [],
   [$3])