Fix evaluation order of hash values for duplicate keys

Fixes [Bug #17719]

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>
Co-authored-by: Ivo Anjo <ivo@ivoanjo.me>

1 files changed, 13 insertions, 7 deletions

diff --git a/parse.y b/parse.y
index bf0d33a491..9f44ff6235 100644
--- a/parse.y
+++ b/parse.y
@@ -12246,24 +12246,30 @@ remove_duplicate_keys(struct parser_params *p, NODE *hash)
 {
     st_table *literal_keys = st_init_table_with_size(&literal_type, hash->nd_alen / 2);
     NODE *result = 0;
+    NODE *last_expr = 0;
     rb_code_location_t loc = hash->nd_loc;
     while (hash && hash->nd_head && hash->nd_next) {
 	NODE *head = hash->nd_head;
 	NODE *value = hash->nd_next;
 	NODE *next = value->nd_next;
-	VALUE key = (VALUE)head;
+	st_data_t key = (st_data_t)head;
 	st_data_t data;
+	value->nd_next = 0;
 	if (nd_type(head) == NODE_LIT &&
-	    st_lookup(literal_keys, (key = head->nd_lit), &data)) {
+	    st_delete(literal_keys, (key = (st_data_t)head->nd_lit, &key), &data)) {
+	    NODE *dup_value = ((NODE *)data)->nd_next;
 	    rb_compile_warn(p->ruby_sourcefile, nd_line((NODE *)data),
 			    "key %+"PRIsVALUE" is duplicated and overwritten on line %d",
 			    head->nd_lit, nd_line(head));
-	    head = ((NODE *)data)->nd_next;
-	    head->nd_head = block_append(p, head->nd_head, value->nd_head);
-	}
-	else {
-	    st_insert(literal_keys, (st_data_t)key, (st_data_t)hash);
+	    if (dup_value == last_expr) {
+		value->nd_head = block_append(p, dup_value->nd_head, value->nd_head);
+	    }
+	    else {
+		last_expr->nd_head = block_append(p, dup_value->nd_head, last_expr->nd_head);
+	    }
 	}
+	st_insert(literal_keys, (st_data_t)key, (st_data_t)hash);
+	last_expr = nd_type(head) == NODE_LIT ? value : head;
 	hash = next;
     }
     st_foreach(literal_keys, append_literal_keys, (st_data_t)&result);