A compilation error with clang++ was fixed in clang 16. See:
$ cat foo.cc
__attribute__ ((__deprecated__)) [[__nodiscard__]] int bar1 (int); // error in
clang < 16
[[__nodiscard__]] __attribute__ ((__deprecated__)) int bar2 (int);
With clang 15:
$ clang++ -S foo.cc
foo.cc:1:34: error: an attribute list cannot appear here
__attribute__ ((__deprecated__)) [[__nodiscard__]] int bar1 (int); // error in
clang < 16
^~~~~~~~~~~~~~~~~
1 error generated.
With clang 16:
$ clang++ -S foo.cc
This patch updates _GL_BRACKET_BEFORE_ATTRIBUTE accordingly.
2024-07-29 Bruno Haible <[email protected]>
An update for clang >= 16.
* m4/gnulib-common.m4 (gl_COMMON_BODY): Don't define
_GL_BRACKET_BEFORE_ATTRIBUTE with clang++ 16 or newer.
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index 71d90dfe71..9602c705e1 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -1,5 +1,5 @@
# gnulib-common.m4
-# serial 96
+# serial 97
dnl Copyright (C) 2007-2024 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
@@ -139,7 +139,7 @@ AC_DEFUN([gl_COMMON_BODY]
various _GL_ATTRIBUTE_* can be cumulated on the same declaration in any
order. */
#ifdef __cplusplus
-# if defined __clang__
+# if defined __clang__ && __clang_major__ < 16
# define _GL_BRACKET_BEFORE_ATTRIBUTE 1
# endif
#else
