[PRISM] Properly support 'it'

prism/prism.c

@@ -18511,7 +18511,6 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
 
                     if (match2(parser, PM_TOKEN_DOT, PM_TOKEN_COLON_COLON)) {
                         receiver = parse_variable_call(parser);
-                        receiver = pm_node_check_it(parser, receiver);
 
                         pm_parser_scope_push(parser, true);
                         lex_state_set(parser, PM_LEX_STATE_FNAME);

prism_compile.c

@@ -6915,6 +6915,15 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
 
         return;
       }
+      case PM_IT_LOCAL_VARIABLE_READ_NODE: {
+        // -> { it }
+        //      ^^
+        if (!popped) {
+            PUSH_GETLOCAL(ret, location, scope_node->local_table_for_iseq_size, 0);
+        }
+
+        return;
+      }
       case PM_KEYWORD_HASH_NODE: {
         // foo(bar: baz)
         //     ^^^^^^^^
@@ -7018,9 +7027,8 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
       case PM_LOCAL_VARIABLE_READ_NODE: {
         // foo
         // ^^^
-        const pm_local_variable_read_node_t *cast = (const pm_local_variable_read_node_t *) node;
-
         if (!popped) {
+            const pm_local_variable_read_node_t *cast = (const pm_local_variable_read_node_t *) node;
             pm_local_index_t index = pm_lookup_local_index(iseq, scope_node, cast->name, cast->depth);
             PUSH_GETLOCAL(ret, location, index.index, index.level);
         }
@@ -7962,6 +7970,12 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
             }
         }
 
+        // If we have the `it` implicit local variable, we need to account for
+        // it in the local table size.
+        if (scope_node->parameters != NULL && PM_NODE_TYPE_P(scope_node->parameters, PM_IT_PARAMETERS_NODE)) {
+            table_size++;
+        }
+
         // Ensure there is enough room in the local table for any
         // parameters that have been repeated
         // ex: def underscore_parameters(_, _ = 1, _ = 2); _; end
@@ -8110,6 +8124,11 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
             body->param.flags.has_lead = true;
         }
 
+        if (scope_node->parameters != NULL && PM_NODE_TYPE_P(scope_node->parameters, PM_IT_PARAMETERS_NODE)) {
+            ID local = rb_make_temporary_id(local_index);
+            local_table_for_iseq->ids[local_index++] = local;
+        }
+
         // def foo(a, (b, *c, d), e = 1, *f, g, (h, *i, j), k:, l: 1, **m, &n)
         //                        ^^^^^
         if (optionals_list && optionals_list->size) {
@@ -8470,18 +8489,6 @@ pm_compile_node(rb_iseq_t *iseq, const pm_node_t *node, LINK_ANCHOR *const ret,
             body->param.flags.has_lead = true;
         }
 
-        // Fill in the it variable, if it exists
-        if (scope_node->parameters && PM_NODE_TYPE_P(scope_node->parameters, PM_IT_PARAMETERS_NODE)) {
-            const uint8_t param_name[] = { '0', 'i', 't' };
-            pm_constant_id_t constant_id = pm_constant_pool_find(&parser->constant_pool, param_name, 3);
-            RUBY_ASSERT(constant_id && "parser should have inserted 0it for 'it' local");
-
-            ID local = rb_make_temporary_id(local_index);
-            local_table_for_iseq->ids[local_index] = local;
-            st_insert(index_lookup_table, (st_data_t) constant_id, (st_data_t) local_index);
-            local_index++;
-        }
-
         //********END OF STEP 3**********
 
         //********STEP 4**********

test/.excludes-prism/TestSyntax.rb

@@ -1,5 +1,4 @@
 exclude(:test_dedented_heredoc_continued_line, "heredoc line continuation dedent calculation")
-exclude(:test_it, "https://github.com/ruby/prism/issues/2323")
 exclude(:test_unterminated_heredoc_cr, "quoted \r heredoc terminators should not match \r\n")
 
 exclude(:test_duplicated_when, "https://bugs.ruby-lang.org/issues/20401")

test/ruby/test_syntax.rb

@@ -1922,7 +1922,7 @@ eom
       ]
     end
     assert_valid_syntax('proc {def foo(_);end;it}')
-    assert_syntax_error('p { [it **2] }', /unexpected \*\*arg/)
+    assert_syntax_error('p { [it **2] }', /unexpected \*\*/)
   end
 
   def test_value_expr_in_condition