Re: [PATCH] sparse: add support for __VA_OPT__

Oh, sorry, Al's branch changed that code more than I imagined.  I would
resend the patch, but I need to figure out this GCC warning...

  CC      pre-process.o
pre-process.c: In function ‘substitute’:
pre-process.c:785:16: warning: function may return address of local variable [-Wreturn-local-addr]
  785 |         return list;
      |                ^~~~
pre-process.c:687:31: note: declared here
  687 |                 struct token *added, *arg;
      |                               ^~~~~

Anyway, here is what I've forward ported.

regards,
dan carpenter

---
 ident-list.h  |  1 +
 pre-process.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/ident-list.h b/ident-list.h
index 3c08e8ca9aa4..556d4050c88d 100644
--- a/ident-list.h
+++ b/ident-list.h
@@ -65,6 +65,7 @@ IDENT(c_generic_selections);
 IDENT(c_static_assert);
 __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 4e322855d600..364c68489a84 100644
--- a/pre-process.c
+++ b/pre-process.c
@@ -638,11 +638,50 @@ static int handle_kludge(const struct token **p, struct arg *args)
 	}
 }
 
+static struct token *get_VA_OPT(const struct token **p, struct arg *args)
+{
+	struct position base_pos = (*p)->pos;
+	struct token *t = (*p)->next;
+	const char *expected;
+	struct token *ret = NULL;
+	struct token *dup, *tail = NULL;
+
+	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, &base_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, const 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;
@@ -692,6 +731,10 @@ static struct token **substitute(struct token **list, const struct token *body,
 
 		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;
@@ -711,6 +754,11 @@ static struct token **substitute(struct token **list, const struct token *body,
 			continue;
 
 		default:
+			if (token_type(body) == TOKEN_IDENT &&
+			    body->ident == &__VA_OPT___ident) {
+				va_opt = get_VA_OPT(&body, args);
+				continue;
+			}
 			added = dup_token(body, base_pos);
 			if (token_type(body) == TOKEN_IDENT &&
 			    added->ident->tainted)
@@ -1094,6 +1142,8 @@ 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;
@@ -1172,6 +1222,9 @@ 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