mirror_zfs/lib/libspl/include/sys/feature_tests.h
Alejandro Colomar db7f1a91de
Use _Noreturn (C11; GNU89) properly
A function that returns with no value is a different thing from a
function that doesn't return at all.  Those are two orthogonal
concepts, commonly confused.

pthread_create(3) expects a pointer to a start routine that has a
very precise prototype:

    void *(*start_routine)(void *);

However, other thread functions, such as kernel ones, expect:

    void (*start_routine)(void *);

Providing a different one is incorrect, and has only been working
because the ABIs happen to produce a compatible function.

We should use '_Noreturn void', since it's the natural type, and
then provide a '_Noreturn void *' wrapper for pthread functions.

For consistency, replace most cases of __NORETURN or
__attribute__((noreturn)) by _Noreturn.  _Noreturn is understood
by -std=gnu89, so it should be safe to use everywhere.

Ref: https://github.com/openzfs/zfs/pull/13110#discussion_r808450136
Ref: https://software.codidact.com/posts/285972
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Co-authored-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Closes #13120
2022-03-04 16:25:22 -08:00

41 lines
1.2 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
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*
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
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*/
/*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#ifndef _SYS_FEATURE_TESTS_H
#define _SYS_FEATURE_TESTS_H
#define ____cacheline_aligned
#if !defined(zfs_fallthrough) && !defined(_LIBCPP_VERSION)
#if defined(HAVE_IMPLICIT_FALLTHROUGH)
#define zfs_fallthrough __attribute__((__fallthrough__))
#else
#define zfs_fallthrough ((void)0)
#endif
#endif
#endif