[PATCH] c2x: message in _Static_assert() is now optional

[Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>]

It seems that in the next version of the standard, the
second argument of _Static_assert() will be optional.

Nice. Let sparse already support this now.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 parse.c                    | 24 ++++++++++++++++--------
 validation/static_assert.c |  5 +++++
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/parse.c b/parse.c
index a9222e7cbf08..bd8989ca8dd4 100644
--- a/parse.c
+++ b/parse.c
@@ -2223,17 +2223,25 @@ static struct token *parse_static_assert(struct token *token, struct symbol_list
 	token = constant_expression(token, &cond);
 	if (!cond)
 		sparse_error(token->pos, "Expected constant expression");
-	token = expect(token, ',', "after conditional expression in _Static_assert");
-	token = string_expression(token, &message, "_Static_assert()");
-	if (!message)
-		cond = NULL;
+	if (match_op(token, ',')) {
+		token = token->next;
+		token = string_expression(token, &message, "_Static_assert()");
+		if (!message)
+			cond = NULL;
+	}
 	token = expect(token, ')', "after diagnostic message in _Static_assert");
-
 	token = expect(token, ';', "after _Static_assert()");
 
-	if (cond && !const_expression_value(cond) && cond->type == EXPR_VALUE)
-		sparse_error(cond->pos, "static assertion failed: %s",
-			     show_string(message->string));
+	if (cond && !const_expression_value(cond) && cond->type == EXPR_VALUE) {
+		const char *sep = "", *msg = "";
+
+		if (message) {
+			sep = ": ";
+			msg = show_string(message->string);
+		}
+		sparse_error(cond->pos, "static assertion failed%s%s", sep, msg);
+	}
+
 	return token;
 }
 
diff --git a/validation/static_assert.c b/validation/static_assert.c
index dd5e0c08c044..0ab5844edef1 100644
--- a/validation/static_assert.c
+++ b/validation/static_assert.c
@@ -53,6 +53,10 @@ _Static_assert(1, );
 _Static_assert(, "");
 _Static_assert(,);
 
+// C2x's version: without message
+_Static_assert(1);
+_Static_assert(0);
+
 /*
  * check-name: static assertion
  *
@@ -67,5 +71,6 @@ static_assert.c:52:19: error: string literal expected for _Static_assert()
 static_assert.c:53:16: error: Expected constant expression
 static_assert.c:54:16: error: Expected constant expression
 static_assert.c:54:17: error: string literal expected for _Static_assert()
+static_assert.c:58:16: error: static assertion failed
  * check-error-end
  */
-- 
2.27.0