Detect duplicate case values.

[r21403]

diff --git a/TODO b/TODO
index 56c6868..7bcd13d 100644 (file)
--- a/TODO
+++ b/TODO
@@ -30,7 +30,6 @@ ast2firm:
 - merge functions entities declared in lokal scope
 
 Missing Errors:
-- check switches for double cases
 
 Missing Warnings:
 - dead assignments (int x = 5; x = bla(); -> dead assignment at x = 5;)

diff --git a/parser.c b/parser.c
index 44ec3f3..0b14a6f 100644 (file)
--- a/parser.c
+++ b/parser.c
@@ -7660,9 +7660,10 @@ static statement_t *parse_case_statement(void)
 {
        eat(T_case);
 
-       statement_t *statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
+       statement_t       *const statement = allocate_statement_zero(STATEMENT_CASE_LABEL);
+       source_position_t *const pos       = &statement->base.source_position;
 
-       statement->base.source_position  = token.source_position;
+       *pos                             = token.source_position;
        statement->case_label.expression = parse_expression();
 
        if (c_mode & _GNUC) {
@@ -7675,22 +7676,30 @@ static statement_t *parse_case_statement(void)
        expect(':');
 
        if (! is_constant_expression(statement->case_label.expression)) {
-               errorf(&statement->base.source_position,
-                      "case label does not reduce to an integer constant");
-       } else {
-               /* TODO: check if the case label is already known */
-               if (current_switch != NULL) {
-                       /* link all cases into the switch statement */
-                       if (current_switch->last_case == NULL) {
-                               current_switch->first_case =
-                               current_switch->last_case  = &statement->case_label;
-                       } else {
-                               current_switch->last_case->next = &statement->case_label;
-                       }
+               errorf(pos, "case label does not reduce to an integer constant");
+       } else if (current_switch != NULL) {
+               /* Check for duplicate case values */
+               /* FIXME slow */
+               long const val = fold_constant(statement->case_label.expression);
+               for (case_label_statement_t *l = current_switch->first_case; l != NULL; l = l->next) {
+                       expression_t const* const e = l->expression;
+                       if (!is_constant_expression(e) || fold_constant(e) != val)
+                               continue;
+
+                       errorf(pos, "duplicate case value");
+                       errorf(&l->base.source_position, "previously used here");
+                       break;
+               }
+
+               /* link all cases into the switch statement */
+               if (current_switch->last_case == NULL) {
+                       current_switch->first_case =
+                               current_switch->last_case = &statement->case_label;
                } else {
-                       errorf(&statement->base.source_position,
-                              "case label not within a switch statement");
+                       current_switch->last_case->next = &statement->case_label;
                }
+       } else {
+               errorf(pos, "case label not within a switch statement");
        }
 
        statement_t *const inner_stmt = parse_statement();