bad-label: mark labels as used when needed

In most cases symbols are automatically marked as being used via
a successfull call to lookup_symbols(), the idea being that the
symbol will be created at its declaration and then any (successfull)
lookup will correspond to an use.

For labels, things are slightly different because labels are
created on-demand via label_symbol() and their use can precede their
'declaration'. And of, course, label_symbol() has no ways to know
if it is used for a definition or an use.

So, fix this by adding an argument to label_symbol(), explictly
telling if the call correspond to an use or not.

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

3 files changed, 8 insertions, 6 deletions

diff --git a/expression.c b/expression.c
index bbbc24e6..99a6d756 100644
--- a/expression.c
+++ b/expression.c
@@ -686,7 +686,7 @@ static struct token *unary_expression(struct token *token, struct expression **t
 		if (match_op(token, SPECIAL_LOGICAL_AND) &&
 		    token_type(token->next) == TOKEN_IDENT) {
 			struct expression *label = alloc_expression(token->pos, EXPR_LABEL);
-			struct symbol *sym = label_symbol(token->next);
+			struct symbol *sym = label_symbol(token->next, 1);
 			if (!(sym->ctype.modifiers & MOD_ADDRESSABLE)) {
 				sym->ctype.modifiers |= MOD_ADDRESSABLE;
 				add_symbol(&function_computed_target_list, sym);
diff --git a/parse.c b/parse.c
index b9d4940e..a8e4a02e 100644
--- a/parse.c
+++ b/parse.c
@@ -726,12 +726,14 @@ static struct symbol * alloc_indirect_symbol(struct position pos, struct ctype *
  * it also ends up using function scope instead of the
  * regular symbol scope.
  */
-struct symbol *label_symbol(struct token *token)
+struct symbol *label_symbol(struct token *token, int used)
 {
 	struct symbol *sym = lookup_symbol(token->ident, NS_LABEL);
 	if (!sym) {
 		sym = alloc_symbol(token->pos, SYM_LABEL);
 		bind_symbol(sym, token->ident, NS_LABEL);
+		if (used)
+			sym->used = 1;
 		fn_local_symbol(sym);
 	}
 	return sym;
@@ -2139,7 +2141,7 @@ static struct token *parse_asm_labels(struct token *token, struct statement *stm
 		token = token->next; /* skip ':' and ',' */
 		if (token_type(token) != TOKEN_IDENT)
 			return token;
-		label = label_symbol(token);
+		label = label_symbol(token, 1);
 		add_symbol(labels, label);
 		token = token->next;
 	} while (match_op(token, ','));
@@ -2509,7 +2511,7 @@ static struct token *parse_goto_statement(struct token *token, struct statement
 		token = parse_expression(token->next, &stmt->goto_expression);
 		add_statement(&function_computed_goto_list, stmt);
 	} else if (token_type(token) == TOKEN_IDENT) {
-		struct symbol *label = label_symbol(token);
+		struct symbol *label = label_symbol(token, 1);
 		stmt->goto_label = label;
 		check_label_usage(label, stmt->pos);
 		token = token->next;
@@ -2563,7 +2565,7 @@ static struct token *statement(struct token *token, struct statement **tree)
 			return s->op->statement(token, stmt);
 
 		if (match_op(token->next, ':')) {
-			struct symbol *s = label_symbol(token);
+			struct symbol *s = label_symbol(token, 0);
 			token = skip_attributes(token->next->next);
 			if (s->stmt) {
 				sparse_error(stmt->pos, "label '%s' redefined", show_ident(s->ident));
diff --git a/parse.h b/parse.h
index 2cfdd872..5ac9a23b 100644
--- a/parse.h
+++ b/parse.h
@@ -124,7 +124,7 @@ extern struct symbol_list *function_computed_target_list;
 extern struct statement_list *function_computed_goto_list;
 
 extern struct token *parse_expression(struct token *, struct expression **);
-extern struct symbol *label_symbol(struct token *token);
+extern struct symbol *label_symbol(struct token *token, int used);
 extern void check_label_usage(struct symbol *label, struct position use_pos);
 
 extern int show_statement(struct statement *);