1 files changed, 12 insertions, 44 deletions

diff --git a/gl/m4/btowc.m4 b/gl/m4/btowc.m4
index d9dd7036..93c9d769 100644
--- a/gl/m4/btowc.m4
+++ b/gl/m4/btowc.m4
@@ -1,17 +1,19 @@
 # btowc.m4
-# serial 14
-dnl Copyright (C) 2008-2024 Free Software Foundation, Inc.
+# serial 16
+dnl Copyright (C) 2008-2026 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.
+dnl This file is offered as-is, without any warranty.
 
 AC_DEFUN([gl_FUNC_BTOWC],
 [
   AC_REQUIRE([gl_WCHAR_H_DEFAULTS])
+  AC_REQUIRE([gt_TYPE_WINT_T])
 
   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>.
+  dnl <https://gcc.gnu.org/PR42440>.
   AC_REQUIRE([gl_WCHAR_H_INLINE_OK])
 
   AC_CHECK_FUNCS_ONCE([btowc])
@@ -52,43 +54,6 @@ 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* | windows*) 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
-      ])
-
     dnl On mingw, in the C locale, btowc is inconsistent with mbrtowc:
     dnl mbrtowc avoids calling MultiByteToWideChar when MB_CUR_MAX is 1 and
     dnl ___lc_codepage_func() is 0, but btowc is lacking this special case.
@@ -133,14 +98,17 @@ int main ()
           ])
       ])
 
+    if test $GNULIBHEADERS_OVERRIDE_WINT_T = 1; then
+      dnl On mingw/ucrt, we override the return type of btowc().
+      dnl While the original wint_t (= unsigned short) and the overridden wint_t
+      dnl (= unsigned int) are equivalent in function parameters, this is not
+      dnl the case for function return types.
+      REPLACE_BTOWC=1
+    fi
     case "$gl_cv_func_btowc_nul" in
       *yes) ;;
       *) REPLACE_BTOWC=1 ;;
     esac
-    case "$gl_cv_func_btowc_eof" in
-      *yes) ;;
-      *) REPLACE_BTOWC=1 ;;
-    esac
     case "$gl_cv_func_btowc_consistent" in
       *yes) ;;
       *) REPLACE_BTOWC=1 ;;