From: Al Viro <viro@zeniv.linux.org.uk>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: "Linus Torvalds" <torvalds@linux-foundation.org>,
"Eugenio Pérez" <eperezma@redhat.com>,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
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Subject: Re: [GIT PULL] __auto_type conversion for v6.19-rc1
Date: Tue, 9 Dec 2025 09:07:07 +0000 [thread overview]
Message-ID: <20251209090707.GV1712166@ZenIV> (raw)
In-Reply-To: <87F4003B-5011-49EF-A807-CEA094EA0DAC@zytor.com>
On Mon, Dec 08, 2025 at 07:28:53PM -0800, H. Peter Anvin wrote:
> Yeah... the C committee even admitted they botched the spec; the intent was for it to work "exactly like gcc __auto_type"...
BTW, speaking of C23 fun that is supported by gcc 8, but not by sparse:
__has_include().
Do we want it? At the moment nothing in the kernel is using that thing.
The main case for that would be <asm/something_optional.h>, and mostly
it's dealt with by dummy asm-generic/something_optional.h and mandatory-y
in asm-generic/Kbuild, but there are at least some cases where we have
it guarded by ifdef, a-la
#ifdef CONFIG_ARCH_HAS_ELFCORE_COMPAT
#include <asm/elfcore-compat.h>
#endif
Linus? Seeing that I'm touching pre-process.c anyway for the sake of
__VA_OPT__, adding that thing ought to be reasonably easy - a bit of
work in expression_value(), the tricky part being where to stop the
scan: __has_include(< => scan to > and demand ) after it,
__has_include(string literal => demand ) after it,
__has_include(anything else => scan to matching ), and expand the
collected tokens. The same dodge we use for #include ("anything
potentially fishy in header-name and it's an UB, so one can
simulate it with other pp-tokens") works here...
next prev parent reply other threads:[~2025-12-09 9:07 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-08 23:55 [GIT PULL] __auto_type conversion for v6.19-rc1 H. Peter Anvin
2025-12-09 0:11 ` pr-tracker-bot
2025-12-09 0:20 ` Linus Torvalds
2025-12-09 0:21 ` H. Peter Anvin
2025-12-09 3:33 ` Linus Torvalds
2025-12-09 8:00 ` Konstantin Ryabitsev
2025-12-09 0:25 ` Al Viro
2025-12-09 0:28 ` H. Peter Anvin
2025-12-09 3:22 ` Al Viro
2025-12-09 3:28 ` H. Peter Anvin
2025-12-09 9:07 ` Al Viro [this message]
2025-12-09 20:40 ` Linus Torvalds
2025-12-09 7:26 ` Linus Torvalds
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