From: Dan Carpenter <dan.carpenter@linaro.org>
To: linux-sparse@vger.kernel.org, Chris Li <chriscli@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ricardo Ribalda <ribalda@chromium.org>,
Hans Verkuil <hverkuil@kernel.org>,
Ben Dooks <ben.dooks@codethink.co.uk>,
Al Viro <viro@zeniv.linux.org.uk>,
Richard Fitzgerald <rf@opensource.cirrus.com>
Subject: [PATCH] sparse: add support for __VA_OPT__
Date: Tue, 24 Feb 2026 14:07:23 +0300 [thread overview]
Message-ID: <c3758782a34bf9ea174a573b50d6af4916edfea8.1771930766.git.dan.carpenter@linaro.org> (raw)
In-Reply-To: <cover.1771930766.git.dan.carpenter@linaro.org>
The linux kernel has started using __VA_OPT__ so lets add support for it.
What it does is it adds an optional thing, normally a comma, if the
__VA_ARGS__ parameter is not empty. So if you have at least one argument
but possibly more then you could create a macro like:
#define test_args(a, ...) printf(a __VA_OPT__(,) __VA_ARGS__)
If you call test_args("foo\n") it expands to:
printf("foo\n");
but if you pass two arguments test_args("foo %d\n", 2) it expands to:
printf("foo\n" , 2);
I guess if you wanted instead of a comma then you could have an empty
__VA_OPT__() or you could pass random things like __VA_OPT__(a b c). I
don't know why you would do that. In this case, "a" is a macro argument
so that has to be expanded out.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
ident-list.h | 1 +
pre-process.c | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
diff --git a/ident-list.h b/ident-list.h
index d65668108385..bffc4038a75d 100644
--- a/ident-list.h
+++ b/ident-list.h
@@ -66,6 +66,7 @@ IDENT(c_static_assert);
__IDENT(pragma_ident, "__pragma__", 0);
__IDENT(_Pragma_ident, "_Pragma", 0);
__IDENT(__VA_ARGS___ident, "__VA_ARGS__", 0);
+__IDENT(__VA_OPT___ident, "__VA_OPT__", 0);
__IDENT(__func___ident, "__func__", 0);
__IDENT(__FUNCTION___ident, "__FUNCTION__", 0);
__IDENT(__PRETTY_FUNCTION___ident, "__PRETTY_FUNCTION__", 0);
diff --git a/pre-process.c b/pre-process.c
index 05a5a79396a8..94710301ce17 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -643,11 +643,49 @@ static int handle_kludge(struct token **p, struct arg *args)
}
}
+static struct token *get_VA_OPT(struct token **p, struct arg *args)
+{
+ struct token *t = (*p)->next;
+ const char *expected;
+ struct token *ret = NULL;
+ struct token *dup, *tail;
+
+ if (token_type(t) != TOKEN_SPECIAL || t->special != '(') {
+ expected = "(";
+ goto error;
+ }
+ while (true) {
+ t = t->next;
+ if (eof_token(t)) {
+ expected = ")";
+ goto error;
+ }
+ if (token_type(t) == TOKEN_SPECIAL &&
+ t->special == ')')
+ break;
+ dup = dup_token(t, &(*p)->pos);
+ if (!ret)
+ ret = dup;
+ else
+ tail->next = dup;
+ tail = dup;
+ }
+
+ if (tail)
+ tail->next = &eof_token_entry;
+ *p = t;
+ return ret;
+error:
+ sparse_error(t->pos, "__VA_OPT__ error: expected '%s'", expected);
+ return NULL;
+}
+
static struct token **substitute(struct token **list, struct token *body, struct arg *args)
{
struct position *base_pos = &(*list)->pos;
int *count;
enum {Normal, Placeholder, Concat} state = Normal;
+ struct token *va_opt = NULL;
for (; !eof_token(body); body = body->next) {
struct token *added, *arg;
@@ -697,6 +735,10 @@ static struct token **substitute(struct token **list, struct token *body, struct
case TOKEN_MACRO_ARGUMENT:
arg = args[body->argnum].expanded;
+ if (va_opt && !eof_token(arg)) {
+ list = substitute(list, va_opt, args);
+ va_opt = NULL;
+ }
count = &args[body->argnum].n_normal;
if (eof_token(arg)) {
state = Normal;
@@ -716,6 +758,11 @@ static struct token **substitute(struct token **list, struct token *body, struct
continue;
case TOKEN_IDENT:
+ if (body->ident == &__VA_OPT___ident) {
+ va_opt = get_VA_OPT(&body, args);
+ continue;
+ }
+
added = dup_token(body, base_pos);
if (added->ident->tainted)
added->pos.noexpand = 1;
@@ -1234,6 +1281,8 @@ static struct token *parse_arguments(struct token *list)
while (token_type(arg) == TOKEN_IDENT) {
if (arg->ident == &__VA_ARGS___ident)
goto Eva_args;
+ if (arg->ident == &__VA_OPT___ident)
+ goto Eva_opt;
if (!++count->normal)
goto Eargs;
next = arg->next;
@@ -1312,6 +1361,9 @@ Enotclosed:
Eva_args:
sparse_error(arg->pos, "__VA_ARGS__ can only appear in the expansion of a C99 variadic macro");
return NULL;
+Eva_opt:
+ sparse_error(arg->pos, "__VA_OPT__ can only appear in the expansion of a C99 variadic macro");
+ return NULL;
Eargs:
sparse_error(arg->pos, "too many arguments in macro definition");
return NULL;
--
2.51.0
next parent reply other threads:[~2026-02-24 11:07 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 ` Dan Carpenter [this message]
2026-02-24 11:16 ` [PATCH] sparse: add support for __VA_OPT__ 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
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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