1 files changed, 105 insertions, 0 deletions
diff --git a/gl/m4/btowc.m4 b/gl/m4/btowc.m4
new file mode 100644
index 0000000..45a61f5
--- /dev/null
+++ b/gl/m4/btowc.m4
@@ -0,0 +1,105 @@
+# btowc.m4 serial 12
+dnl Copyright (C) 2008-2022 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.
+
+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 <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42440>.
+  AC_REQUIRE([gl_WCHAR_H_INLINE_OK])
+
+  AC_CHECK_FUNCS_ONCE([btowc])
+  if test $ac_cv_func_btowc = no; then
+    HAVE_BTOWC=0
+  else
+
+    AC_REQUIRE([AC_PROG_CC])
+    AC_REQUIRE([gt_LOCALE_FR])
+    AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
+
+    dnl Cygwin 1.7.2 btowc('\0') is WEOF, not 0.
+    AC_CACHE_CHECK([whether btowc(0) is correct],
+      [gl_cv_func_btowc_nul],
+      [
+        AC_RUN_IFELSE(
+          [AC_LANG_SOURCE([[
+#include <wchar.h>
+int main ()
+{
+  if (btowc ('\0') != 0)
+    return 1;
+  return 0;
+}]])],
+          [gl_cv_func_btowc_nul=yes],
+          [gl_cv_func_btowc_nul=no],
+          [
+changequote(,)dnl
+           case "$host_os" in
+                      # Guess no on Cygwin.
+             cygwin*) gl_cv_func_btowc_nul="guessing no" ;;
+                      # Guess yes on native Windows.
+             mingw*)  gl_cv_func_btowc_nul="guessing yes" ;;
+                      # 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],
+      [
+        dnl Initial guess, used when cross-compiling or when no suitable locale
+        dnl is present.
+changequote(,)dnl
+        case "$host_os" in
+                  # Guess no on IRIX.
+          irix*)  gl_cv_func_btowc_eof="guessing no" ;;
+                  # Guess yes on native Windows.
+          mingw*) gl_cv_func_btowc_eof="guessing yes" ;;
+                  # Guess yes otherwise.
+          *)      gl_cv_func_btowc_eof="guessing yes" ;;
+        esac
+changequote([,])dnl
+        if test $LOCALE_FR != none; then
+          AC_RUN_IFELSE(
+            [AC_LANG_SOURCE([[
+#include <locale.h>
+#include <stdio.h>
+#include <wchar.h>
+int main ()
+{
+  if (setlocale (LC_ALL, "$LOCALE_FR") != NULL)
+    {
+      if (btowc (EOF) != WEOF)
+        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 ;;
+    esac
+  fi
+])
+
+# Prerequisites of lib/btowc.c.
+AC_DEFUN([gl_PREREQ_BTOWC], [
+  :
+])