Merging upstream version 5.6.2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 23 insertions, 4 deletions

diff --git a/src/common/tuklib_common.h b/src/common/tuklib_common.h
index b1f531e..7554dfc 100644
--- a/src/common/tuklib_common.h
+++ b/src/common/tuklib_common.h
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: 0BSD
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 /// \file       tuklib_common.h
@@ -5,9 +7,6 @@
 //
 //  Author:     Lasse Collin
 //
-//  This file has been put into the public domain.
-//  You can do whatever you want with this file.
-//
 ///////////////////////////////////////////////////////////////////////////////
 
 #ifndef TUKLIB_COMMON_H
@@ -57,8 +56,28 @@
 #	define TUKLIB_GNUC_REQ(major, minor) 0
 #endif
 
-#if TUKLIB_GNUC_REQ(2, 5)
+// tuklib_attr_noreturn attribute is used to mark functions as non-returning.
+// We cannot use "noreturn" as the macro name because then C23 code that
+// uses [[noreturn]] would break as it would expand to [[ [[noreturn]] ]].
+//
+// tuklib_attr_noreturn must be used at the beginning of function declaration
+// to work in all cases. The [[noreturn]] syntax is the most limiting, it
+// must be even before any GNU C's __attribute__ keywords:
+//
+//     tuklib_attr_noreturn
+//     __attribute__((nonnull(1)))
+//     extern void foo(const char *s);
+//
+// FIXME: Update __STDC_VERSION__ for the final C23 version. 202000 is used
+// by GCC 13 and Clang 15 with -std=c2x.
+#if   defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202000
+#	define tuklib_attr_noreturn [[noreturn]]
+#elif defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112
+#	define tuklib_attr_noreturn _Noreturn
+#elif TUKLIB_GNUC_REQ(2, 5)
 #	define tuklib_attr_noreturn __attribute__((__noreturn__))
+#elif defined(_MSC_VER)
+#	define tuklib_attr_noreturn __declspec(noreturn)
 #else
 #	define tuklib_attr_noreturn
 #endif