From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 13 Sep 2022 17:41:34 +0000 (-0500)
Subject: Port alignas definition to C23
X-Git-Tag: emacs-29.0.90~1856^2~540
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=49419912f20b3cf0131a40798b162cbb596d368e;p=emacs.git

Port alignas definition to C23

* src/lisp.h (alignas): C23 is removing the __alignas_is_defined
macro, so do not rely on it. Instead, do not define alignas if C23
or later, or if C++11 or later.
---

diff --git a/src/lisp.h b/src/lisp.h
index 2f73ba4c617..9710dbef8d2 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -245,7 +245,8 @@ DEFINE_GDB_SYMBOL_BEGIN (EMACS_INT, VALMASK)
 DEFINE_GDB_SYMBOL_END (VALMASK)
 
 /* Ignore 'alignas' on compilers lacking it.  */
-#if !defined alignas && !defined __alignas_is_defined
+#if (!defined alignas && !defined __alignas_is_defined \
+     && __STDC_VERSION__ < 202311 && __cplusplus < 201103)
 # define alignas(a)
 #endif