git: 066069197864 - stable/13 - cdefs: Add __writeonly to mark write only vars

The branch stable/13 has been updated by andrew:

URL: https://cgit.FreeBSD.org/src/commit/?id=06606919786416d9854a16ad856ed89582856f16

commit 06606919786416d9854a16ad856ed89582856f16
Author:     Andrew Turner <andrew@FreeBSD.org>
AuthorDate: 2024-06-12 13:04:13 +0000
Commit:     Andrew Turner <andrew@FreeBSD.org>
CommitDate: 2024-07-15 12:35:21 +0000

    cdefs: Add __writeonly to mark write only vars
    
    When a variable in write only and can't be removed, e.g. for API
    reasons, it is useful to document this fact similar to __diagused
    and __witness_used.
    
    Add __writeonly to tell the compiler and anyone looking at the code
    that this variable is expected to only be written to, and to not
    raise and error.
    
    Reviewed by:    imp, kib
    Sponsored by:   Arm Ltd
    Differential Revision:  https://reviews.freebsd.org/D45561
    
    (cherry picked from commit a7ae78caaa17ff840da844c1dcaa780d194c9e20)
---
 sys/sys/cdefs.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h
index df15a3c04193..d9e1c476f1ef 100644
--- a/sys/sys/cdefs.h
+++ b/sys/sys/cdefs.h
@@ -219,6 +219,7 @@
 #define	__aligned(x)	__attribute__((__aligned__(x)))
 #define	__section(x)	__attribute__((__section__(x)))
 #endif
+#define	__writeonly	__unused
 #if __GNUC_PREREQ__(4, 3) || __has_attribute(__alloc_size__)
 #define	__alloc_size(x)	__attribute__((__alloc_size__(x)))
 #define	__alloc_size2(n, x)	__attribute__((__alloc_size__(n, x)))