Warn about empty declarations.

[r18436]

diff --git a/parser.c b/parser.c
index b5f8971..78bc75a 100644 (file)
--- a/parser.c
+++ b/parser.c
@@ -208,12 +208,18 @@ static void parser_print_warning_prefix_pos(
        fputs("warning: ", stderr);
 }
 
-static void parse_warning(const char *message)
+static void parse_warning_pos(const source_position_t source_position,
+                              const char *const message)
 {
-       parser_print_prefix_pos(token.source_position);
+       parser_print_prefix_pos(source_position);
        fprintf(stderr, "warning: %s\n", message);
 }
 
+static void parse_warning(const char *message)
+{
+       parse_warning_pos(token.source_position, message);
+}
+
 static void parse_error_expected(const char *message, ...)
 {
        va_list args;
@@ -1947,6 +1953,29 @@ static void parse_declaration(void)
        parse_declaration_specifiers(&specifiers);
 
        if(token.type == ';') {
+               if (specifiers.storage_class != STORAGE_CLASS_NONE) {
+                       parse_warning_pos(source_position,
+                                         "useless keyword in empty declaration");
+               }
+               switch (specifiers.type->type) {
+                       case TYPE_COMPOUND_STRUCT:
+                       case TYPE_COMPOUND_UNION: {
+                               const compound_type_t *const comp_type =
+                                       (const compound_type_t*)specifiers.type;
+                               if (comp_type->declaration->symbol == NULL) {
+                                       parse_warning_pos(source_position,
+                                                                                                               "unnamed struct/union that defines no instances");
+                               }
+                               break;
+                       }
+
+                       case TYPE_ENUM: break;
+
+                       default:
+                               parse_warning_pos(source_position, "empty declaration");
+                               break;
+               }
+
                next_token();
 
                declaration_t *declaration = allocate_ast_zero(sizeof(declaration[0]));