[PATCH] maint.mk: Modernize stddef.h checks for C23

[Paul Eggert]

* top/maint.mk (_stddef_syms_re): Modernize for C23.
---
 ChangeLog    | 5 +++++
 top/maint.mk | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index 382c6d0317..5eced13c36 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2023-07-01  Paul Eggert  <eggert@cs.ucla.edu>
+
+       maint.mk: Modernize stddef.h checks for C23
+       * top/maint.mk (_stddef_syms_re): Modernize for C23.
+
 2023-07-01  Bruno Haible  <bruno@clisp.org>
 
        quotearg: Overcome wchar_t limitations.
diff --git a/top/maint.mk b/top/maint.mk
index 5bc6442710..edcf3c7049 100644
--- a/top/maint.mk
+++ b/top/maint.mk
@@ -736,7 +736,8 @@ sc_prohibit_intprops_without_use:
        re='\<($(_intprops_syms_re)) *\('                               \
          $(_sc_header_without_use)
 
-_stddef_syms_re = NULL|offsetof|ptrdiff_t|size_t|wchar_t
+_stddef_syms_re = \
+  NULL|max_align_t|nullptr_t|offsetof|ptrdiff_t|size_t|unreachable|wchar_t
 # Prohibit the inclusion of stddef.h without an actual use.
 sc_prohibit_stddef_without_use:
        @h='stddef.h'                                                   \
-- 
2.41.0