fix crash when mode attribut misses arguments

diff --git a/attribute.c b/attribute.c
index 2c5e90b..3eafe94 100644 (file)
--- a/attribute.c
+++ b/attribute.c
@@ -144,9 +144,15 @@ type_t *handle_attribute_mode(const attribute_t *attribute, type_t *orig_type)
 
        /* This isn't really correct, the backend should provide a list of machine
         * specific modes (according to gcc philosophy that is...) */
-       attribute_argument_t *arg        = attribute->a.arguments;
-       const char           *symbol_str = arg->v.symbol->string;
-       bool                  sign       = is_type_signed(type);
+       attribute_argument_t *arg = attribute->a.arguments;
+       if (arg == NULL) {
+               errorf(&attribute->source_position,
+                      "__attribute__((mode(X))) misses argument");
+               return orig_type;
+       }
+
+       const char         *symbol_str = arg->v.symbol->string;
+       bool                sign       = is_type_signed(type);
        atomic_type_kind_t  akind;
        if (strcmp_underscore("QI",   symbol_str) == 0 ||
            strcmp_underscore("byte", symbol_str) == 0) {