1 files changed, 116 insertions, 15 deletions

diff --git a/gl/stddef.in.h b/gl/stddef.in.h
index 6eadcc3d..e8c55ff1 100644
--- a/gl/stddef.in.h
+++ b/gl/stddef.in.h
@@ -1,6 +1,6 @@
 /* A substitute for POSIX 2008 <stddef.h>, for platforms that have issues.
 
-   Copyright (C) 2009-2023 Free Software Foundation, Inc.
+   Copyright (C) 2009-2025 Free Software Foundation, Inc.
 
    This file is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as
@@ -18,7 +18,7 @@
 /* Written by Eric Blake.  */
 
 /*
- * POSIX 2008 <stddef.h> for platforms that have issues.
+ * POSIX 2008 and ISO C 23 <stddef.h> for platforms that have issues.
  * <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/stddef.h.html>
  */
 
@@ -27,19 +27,27 @@
 #endif
 @PRAGMA_COLUMNS@
 
-#if defined __need_wchar_t || defined __need_size_t  \
-  || defined __need_ptrdiff_t || defined __need_NULL \
-  || defined __need_wint_t
+#if (defined __need_wchar_t || defined __need_size_t                \
+     || defined __need_ptrdiff_t || defined __need_NULL             \
+     || defined __need_wint_t)                                      \
+    /* Avoid warning triggered by "gcc -std=gnu23 -Wsystem-headers" \
+       in GCC 13.3 and 14.2                                         \
+       <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114870>.  */   \
+    && !@STDDEF_NOT_IDEMPOTENT@
 /* Special invocation convention inside gcc header files.  In
-   particular, gcc provides a version of <stddef.h> that blindly
-   redefines NULL even when __need_wint_t was defined, even though
-   wint_t is not normally provided by <stddef.h>.  Hence, we must
+   particular, <stddef.h> in some ancient versions of GCC blindly
+   redefined NULL when __need_wint_t was defined, even though wint_t
+   is not normally provided by <stddef.h>.
+   (FIXME: It's not clear what GCC versions those were - perhaps so
+   ancient that we can stop worrying about this?)
+   Although glibc 2.26 (2017) and later do not use __need_wint_t,
+   for portability to macOS, Cygwin, Haiku, and older Glibc + GCC,
    remember if special invocation has ever been used to obtain wint_t,
    in which case we need to clean up NULL yet again.  */
 
-# if !(defined _@GUARD_PREFIX@_STDDEF_H && defined _GL_STDDEF_WINT_T)
+# if !(defined _@GUARD_PREFIX@_STDDEF_H && defined _@GUARD_PREFIX@_STDDEF_WINT_T)
 #  ifdef __need_wint_t
-#   define _GL_STDDEF_WINT_T
+#   define _@GUARD_PREFIX@_STDDEF_WINT_T
 #  endif
 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
    /* On TinyCC, make sure that the macros that indicate the special invocation
@@ -52,13 +60,20 @@
 # endif
 
 #else
+/* For @STDDEF_NOT_IDEMPOTENT@.  */
+# undef __need_wchar_t
+# undef __need_size_t
+# undef __need_ptrdiff_t
+# undef __need_NULL
+# undef __need_wint_t
+
 /* Normal invocation convention.  */
 
 # ifndef _@GUARD_PREFIX@_STDDEF_H
 
 /* On AIX 7.2, with xlc in 64-bit mode, <stddef.h> defines max_align_t to a
    type with alignment 4, but 'long' has alignment 8.  */
-#  if defined _AIX && defined __LP64__
+#  if defined _AIX && defined __LP64__ && !@HAVE_MAX_ALIGN_T@
 #   if !GNULIB_defined_max_align_t
 #    ifdef _MAX_ALIGN_T
 /* /usr/include/stddef.h has already defined max_align_t.  Override it.  */
@@ -69,17 +84,24 @@ typedef long rpl_max_align_t;
 typedef long max_align_t;
 #     define _MAX_ALIGN_T
 #    endif
+#    define __CLANG_MAX_ALIGN_T_DEFINED
 #    define GNULIB_defined_max_align_t 1
 #   endif
 #  endif
 
+#  if !defined _GCC_NULLPTR_T && !@NULLPTR_T_NEEDS_STDDEF@
+    /* Suppress unwanted nullptr_t typedef.  See
+       <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114869>.  */
+#   define _GCC_NULLPTR_T
+#  endif
+
 /* The include_next requires a split double-inclusion guard.  */
 
 #  @INCLUDE_NEXT@ @NEXT_STDDEF_H@
 
 /* On NetBSD 5.0, the definition of NULL lacks proper parentheses.  */
 #  if (@REPLACE_NULL@ \
-       && (!defined _@GUARD_PREFIX@_STDDEF_H || defined _GL_STDDEF_WINT_T))
+       && (!defined _@GUARD_PREFIX@_STDDEF_H || defined _@GUARD_PREFIX@_STDDEF_WINT_T))
 #   undef NULL
 #   ifdef __cplusplus
    /* ISO C++ says that the macro NULL must expand to an integer constant
@@ -100,9 +122,31 @@ typedef long max_align_t;
 #  ifndef _@GUARD_PREFIX@_STDDEF_H
 #   define _@GUARD_PREFIX@_STDDEF_H
 
-/* Some platforms lack wchar_t.  */
-#if !@HAVE_WCHAR_T@
-# define wchar_t int
+/* This file uses _Noreturn, _GL_ATTRIBUTE_NOTHROW.  */
+#if !_GL_CONFIG_H_INCLUDED
+ #error "Please include config.h first."
+#endif
+
+/* _GL_ATTRIBUTE_NOTHROW declares that the function does not throw exceptions.
+ */
+#ifndef _GL_ATTRIBUTE_NOTHROW
+# if defined __cplusplus
+#  if (__GNUC__ + (__GNUC_MINOR__ >= 8) > 2) || __clang_major__ >= 4
+#   if __cplusplus >= 201103L
+#    define _GL_ATTRIBUTE_NOTHROW noexcept (true)
+#   else
+#    define _GL_ATTRIBUTE_NOTHROW throw ()
+#   endif
+#  else
+#   define _GL_ATTRIBUTE_NOTHROW
+#  endif
+# else
+#  if (__GNUC__ + (__GNUC_MINOR__ >= 3) > 3) || defined __clang__
+#   define _GL_ATTRIBUTE_NOTHROW __attribute__ ((__nothrow__))
+#  else
+#   define _GL_ATTRIBUTE_NOTHROW
+#  endif
+# endif
 #endif
 
 /* Some platforms lack max_align_t.  The check for _GCC_MAX_ALIGN_T is
@@ -137,11 +181,68 @@ typedef union
   long int __i _GL_STDDEF_ALIGNAS (long int);
 } rpl_max_align_t;
 #   define max_align_t rpl_max_align_t
+#   define __CLANG_MAX_ALIGN_T_DEFINED
 #   define GNULIB_defined_max_align_t 1
 #  endif
 # endif
 #endif
 
+/* ISO C 23 § 7.21.1 The unreachable macro  */
+/* This macro is only usable in C, not in C++.
+   There is no way to define it as a macro in C++, because that would break code
+   that does
+       #include <utility>
+       ... std::unreachable() ...
+   Similarly, there is no way to define it as an inline function in C++, because
+   that would break code that does
+       #include <utility>
+       using std::unreachable;
+   As a workaround, we define a macro gl_unreachable, that is like unreachable,
+   but is usable in both C and C++.  */
+
+/* Code borrowed from verify.h.  */
+#ifndef _GL_HAS_BUILTIN_UNREACHABLE
+# if defined __clang_major__ && __clang_major__ < 5
+#  define _GL_HAS_BUILTIN_UNREACHABLE 0
+# elif 4 < __GNUC__ + (5 <= __GNUC_MINOR__) && !defined __clang__
+#  define _GL_HAS_BUILTIN_UNREACHABLE 1
+# elif defined __has_builtin
+#  define _GL_HAS_BUILTIN_UNREACHABLE __has_builtin (__builtin_unreachable)
+# else
+#  define _GL_HAS_BUILTIN_UNREACHABLE 0
+# endif
+#endif
+
+#if _GL_HAS_BUILTIN_UNREACHABLE
+# define gl_unreachable() __builtin_unreachable ()
+#elif 1200 <= _MSC_VER
+# define gl_unreachable() __assume (0)
+#elif !defined __cplusplus && @HAVE_C_UNREACHABLE@
+# define gl_unreachable() unreachable ()
+#else
+/* Declare abort(), without including <stdlib.h>.  */
+extern
+# if defined __cplusplus
+"C"
+# endif
+_Noreturn
+void abort (void)
+# if defined __cplusplus && (__GLIBC__ >= 2)
+_GL_ATTRIBUTE_NOTHROW
+# endif
+;
+# define gl_unreachable() abort ()
+#endif
+
+#if !defined __cplusplus && !@HAVE_C_UNREACHABLE@
+/* In C, define unreachable as a macro.  */
+
+# ifndef unreachable
+#  define unreachable() gl_unreachable ()
+# endif
+
+#endif
+
 #  endif /* _@GUARD_PREFIX@_STDDEF_H */
 # endif /* _@GUARD_PREFIX@_STDDEF_H */
 #endif /* __need_XXX */