asm: warn on invalid empty constraints

Empty ASM constraints are invalid. So, catch them
at parsing time and issue a warning.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/evaluate.c b/evaluate.c
index 919c944c..74c7fd1d 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -3503,6 +3503,9 @@ static void parse_asm_constraint(struct asm_operand *op)
 	int c;
 
 	switch (str[0]) {
+	case '\0':
+		sparse_error(constraint->pos, "invalid ASM constraint (\"\")");
+		break;
 	case '+':
 		op->is_modify = true;
 		/* fall-through */