X-Git-Url: https://git.cworth.org/git?a=blobdiff_plain;f=m4%2Fbtowc.m4;h=b16b1f020a94bef677777b9de347853952144cb8;hb=de7372b23c3da92fbfaea2d1ac592f0b2ba87914;hp=64ff82906155bcfbf1cfdaaa4258c3221bbcebfa;hpb=9fb70f2dfbea87fd0a624a5addf03fcbafc9b48a;p=tar

diff --git a/m4/btowc.m4 b/m4/btowc.m4
index 64ff829..b16b1f0 100644
--- a/m4/btowc.m4
+++ b/m4/btowc.m4
@@ -1,5 +1,5 @@
-# btowc.m4 serial 3
-dnl Copyright (C) 2008 Free Software Foundation, Inc.
+# btowc.m4 serial 7
+dnl Copyright (C) 2008-2010 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.
@@ -8,15 +8,50 @@ AC_DEFUN([gl_FUNC_BTOWC],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
 
+  dnl Check whether <wchar.h> is usable at all, first. Otherwise the test
+  dnl program below may lead to an endless loop. See
+  dnl <http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42440>.
+  AC_REQUIRE([gl_WCHAR_H_INLINE_OK])
+
   AC_CHECK_FUNCS_ONCE([btowc])
   if test $ac_cv_func_btowc = no; then
     HAVE_BTOWC=0
   else
 
-    dnl IRIX 6.5 btowc(EOF) is 0xFF, not WEOF.
     AC_REQUIRE([AC_PROG_CC])
     AC_REQUIRE([gt_LOCALE_FR])
     AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+    dnl Cygwin 1.7.2 btowc('\0') is WEOF, not 0.
+    AC_CACHE_CHECK([whether btowc(0) is correct],
+      [gl_cv_func_btowc_nul],
+      [
+        AC_RUN_IFELSE(
+          [AC_LANG_SOURCE([[
+#include <stdio.h>
+#include <string.h>
+#include <wchar.h>
+int main ()
+{
+  if (btowc ('\0') != 0)
+    return 1;
+  return 0;
+}]])],
+          [gl_cv_func_btowc_nul=yes],
+          [gl_cv_func_btowc_nul=no],
+          [
+changequote(,)dnl
+           case "$host_os" in
+                      # Guess no on Cygwin.
+             cygwin*) gl_cv_func_btowc_nul="guessing no" ;;
+                      # Guess yes otherwise.
+             *)       gl_cv_func_btowc_nul="guessing yes" ;;
+           esac
+changequote([,])dnl
+          ])
+      ])
+
+    dnl IRIX 6.5 btowc(EOF) is 0xFF, not WEOF.
     AC_CACHE_CHECK([whether btowc(EOF) is correct],
       [gl_cv_func_btowc_eof],
       [
@@ -31,7 +66,8 @@ changequote(,)dnl
         esac
 changequote([,])dnl
         if test $LOCALE_FR != none; then
-          AC_TRY_RUN([
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
 #include <locale.h>
 #include <stdio.h>
 #include <string.h>
@@ -44,12 +80,17 @@ int main ()
         return 1;
     }
   return 0;
-}],
+}]])],
             [gl_cv_func_btowc_eof=yes],
             [gl_cv_func_btowc_eof=no],
-            [])
+            [:])
         fi
       ])
+
+    case "$gl_cv_func_btowc_nul" in
+      *yes) ;;
+      *) REPLACE_BTOWC=1 ;;
+    esac
     case "$gl_cv_func_btowc_eof" in
       *yes) ;;
       *) REPLACE_BTOWC=1 ;;