From: Al Viro <viro@zeniv.linux.org.uk>
To: Eric Zhang <zxh@xh-zhang.com>
Cc: linux-sparse@vger.kernel.org, dan.carpenter@linaro.org,
chriscli@google.com, ben.dooks@codethink.co.uk,
rf@opensource.cirrus.com, torvalds@linux-foundation.org
Subject: Re: [RFC PATCH] pre-process: add __VA_OPT__ support
Date: Wed, 25 Feb 2026 06:40:03 +0000 [thread overview]
Message-ID: <20260225064003.GD1762976@ZenIV> (raw)
In-Reply-To: <20260225052950.2444262-1-zxh@xh-zhang.com>
On Tue, Feb 24, 2026 at 09:29:50PM -0800, Eric Zhang wrote:
> Add __VA_OPT__ support (C23 6.10.5) including some tests.
>
> At expansion time, substitute() checks whether the variadic
> argument is empty: if so, skip the region between the markers;
> otherwise, process the enclosed tokens normally.
>
> Signed-off-by: Eric Zhang <zxh@xh-zhang.com>
> ---
> Discussed this with Chris during lunch yesterday and got curious
> about the problem, so made a few attempts. Introducing
> TOKEN_VA_OPT_START/END feels a bit like an anti-pattern, but I
> couldn't find a cleaner way to handle it without new token types.
> Happy to hear suggestions.
Your variant will break with __VA_OPT__ following #. It won't do the
right thing with ## either, AFAICS, in case when __VA_OPT__ token list
is empty.
next prev parent reply other threads:[~2026-02-25 6:37 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1771930766.git.dan.carpenter@linaro.org>
2026-02-24 11:07 ` [PATCH] sparse: add support for __VA_OPT__ Dan Carpenter
2026-02-24 11:16 ` Ben Dooks
2026-02-24 11:56 ` Dan Carpenter
2026-02-24 12:42 ` Richard Fitzgerald
2026-02-24 13:15 ` Ben Dooks
2026-02-25 2:39 ` Chris Li
2026-02-25 3:36 ` Al Viro
2026-02-25 5:29 ` [RFC PATCH] pre-process: add __VA_OPT__ support Eric Zhang
2026-02-25 6:40 ` Al Viro [this message]
2026-02-25 7:27 ` Al Viro
2026-02-25 8:14 ` Eric Zhang
2026-02-25 22:18 ` Al Viro
2026-02-26 7:29 ` Al Viro
2026-03-16 6:56 ` Al Viro
2026-03-16 7:03 ` [PATCH 01/21] split copy() into "need to copy" and "can move in place" cases Al Viro
2026-03-16 7:03 ` [PATCH 02/21] expand and simplify the call of dup_token() in copy() Al Viro
2026-03-16 7:03 ` [PATCH 03/21] more dup_token() optimizations Al Viro
2026-03-16 7:03 ` [PATCH 04/21] parsing #define: saner handling of argument count, part 1 Al Viro
2026-03-16 7:03 ` [PATCH 05/21] simplify collect_arguments() and fix error handling there Al Viro
2026-03-16 7:04 ` [PATCH 06/21] try_arg(): don't use arglist for argument name lookups Al Viro
2026-03-16 7:04 ` [PATCH 07/21] make expand_has_...() responsible for expanding its argument Al Viro
2026-03-16 7:04 ` [PATCH 08/21] preparing to change argument number encoding for TOKEN_..._ARGUMENT Al Viro
2026-03-16 7:04 ` [PATCH 09/21] steal 2 bits from argnum for argument kind Al Viro
2026-03-16 7:04 ` [PATCH 10/21] on-demand argument expansion Al Viro
2026-03-16 7:04 ` [PATCH 11/21] kill create_arglist() Al Viro
2026-03-16 7:04 ` [PATCH 12/21] stop mangling arglist, get rid of TOKEN_ARG_COUNT Al Viro
2026-03-16 7:04 ` [PATCH 13/21] deal with ## on arguments separately Al Viro
2026-03-16 7:04 ` [PATCH 14/21] preparations for __VA_OPT__ support: reshuffle argument slot assignments Al Viro
2026-03-16 7:04 ` [PATCH 15/21] pre-process.c: split try_arg() Al Viro
2026-03-16 7:04 ` [PATCH 16/21] __VA_OPT__: parsing Al Viro
2026-05-04 11:56 ` Dan Carpenter
2026-03-16 7:04 ` [PATCH 17/21] expansion-time va_opt handling Al Viro
2026-03-16 7:04 ` [PATCH 18/21] merge(): saner handling of ->noexpand Al Viro
2026-03-16 7:04 ` [PATCH 19/21] simplify the calling conventions of collect_arguments() Al Viro
2026-03-16 7:04 ` [PATCH 20/21] make expand_one_symbol() inline Al Viro
2026-03-16 7:04 ` [PATCH 21/21] substitute(): convert switch() into cascade of ifs Al Viro
2026-03-16 16:42 ` [RFC PATCH] pre-process: add __VA_OPT__ support Linus Torvalds
2026-03-19 3:53 ` Al Viro
2026-03-19 4:07 ` Linus Torvalds
2026-03-19 5:34 ` Al Viro
2026-03-17 7:41 ` Chris Li
2026-03-18 6:35 ` Eric Zhang
2026-03-31 8:06 ` Al Viro
2026-03-31 8:07 ` [PATCH 1/6] nextchar(): get rid of special[] Al Viro
2026-03-31 8:07 ` [PATCH 2/6] simplify the inlined side of nextchar() Al Viro
2026-03-31 8:07 ` [PATCH 3/6] tokenize_stream(): don't bother with isspace() Al Viro
2026-03-31 8:07 ` [PATCH 4/6] TOKEN_DIRECTIVE: recognize directive-introducing # in tokenizer Al Viro
2026-03-31 8:07 ` [PATCH 5/6] saner collect_arg() code generation Al Viro
2026-03-31 8:07 ` [PATCH 6/6] try to get whitespaces right Al Viro
2026-04-01 10:39 ` [RFC PATCH] pre-process: add __VA_OPT__ support Al Viro
2026-04-01 16:18 ` Linus Torvalds
2026-04-01 19:52 ` Al Viro
2026-04-01 20:22 ` Al Viro
2026-02-25 7:05 ` [PATCH] sparse: add support for __VA_OPT__ Chris Li
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