[Bug #21669] Remove invalid marking local variable assignment mark

Author: nobu

parse.y

@@ -13900,7 +13900,7 @@ value_expr_check(struct parser_params *p, NODE *node)
           case NODE_BLOCK:
             while (RNODE_BLOCK(node)->nd_next) {
                 vn = value_expr_check(p, RNODE_BLOCK(node)->nd_head);
-                if (vn) return vn;
+                if (vn && !void_node) void_node = vn;
                 node = RNODE_BLOCK(node)->nd_next;
             }
             node = RNODE_BLOCK(node)->nd_head;
@@ -13929,12 +13929,6 @@ value_expr_check(struct parser_params *p, NODE *node)
             node = RNODE_AND(node)->nd_1st;
             break;
 
-          case NODE_LASGN:
-          case NODE_DASGN:
-          case NODE_MASGN:
-            mark_lvar_used(p, node);
-            return NULL;
-
           default:
             return NULL;
         }

test/ruby/test_parse.rb

@@ -1148,6 +1148,16 @@ def test_unused_variable
     assert_warning(/assigned but unused variable/) {o.instance_eval("def bar2; a, = 1, 2; end")}
     assert_warning('') {o.instance_eval("def marg1(a); nil; end")}
     assert_warning('') {o.instance_eval("def marg2((a)); nil; end")}
+
+    assert_warning(/assigned but unused variable/) {o.instance_eval("#{<<~"{#"}\n#{<<~'};'}")}
+    {#
+      def zot
+        block ||= begin
+          foo = nil
+          itself
+        end
+      end
+    };
   end
 
   def test_parsing_begin_statement_inside_method_definition