Merge from gnulib.

2013-05-15 manywarnings: update for GCC 4.8.0
2013-05-15 stdio: use __REDIRECT for fwrite, fwrite_unlocked
2013-05-15 sig2str, stdio, warnings: port to clang

2 files changed, 14 insertions, 7 deletions

diff --git a/m4/manywarnings.m4 b/m4/manywarnings.m4
index 45a30afda70..be6d4c91c50 100644
--- a/m4/manywarnings.m4
+++ b/m4/manywarnings.m4
@@ -98,6 +98,7 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -W \
     -Wabi \
     -Waddress \
+    -Waggressive-loop-optimizations \
     -Wall \
     -Warray-bounds \
     -Wattributes \
@@ -125,7 +126,6 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -Wformat-security \
     -Wformat-y2k \
     -Wformat-zero-length \
-    -Wformat=2 \
     -Wfree-nonheap-object \
     -Wignored-qualifiers \
     -Wimplicit \
@@ -143,9 +143,7 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -Wmissing-braces \
     -Wmissing-declarations \
     -Wmissing-field-initializers \
-    -Wmissing-format-attribute \
     -Wmissing-include-dirs \
-    -Wmissing-noreturn \
     -Wmissing-parameter-type \
     -Wmissing-prototypes \
     -Wmudflap \
@@ -166,6 +164,7 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -Wpointer-sign \
     -Wpointer-to-int-cast \
     -Wpragmas \
+    -Wreturn-local-addr \
     -Wreturn-type \
     -Wsequence-point \
     -Wshadow \
@@ -187,7 +186,6 @@ AC_DEFUN([gl_MANYWARN_ALL_GCC],
     -Wtype-limits \
     -Wuninitialized \
     -Wunknown-pragmas \
-    -Wunreachable-code \
     -Wunsafe-loop-optimizations \
     -Wunused \
     -Wunused-but-set-parameter \
diff --git a/m4/warnings.m4 b/m4/warnings.m4
index 4b2ac385019..184873283bb 100644
--- a/m4/warnings.m4
+++ b/m4/warnings.m4
@@ -1,4 +1,4 @@
-# warnings.m4 serial 7
+# 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,
@@ -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])