[ruby/prism] Syntax error for block argument on yield

https://github.com/ruby/prism/commit/9feeafbc67

prism/config.yml

@@ -235,6 +235,7 @@ errors:
   - TERNARY_EXPRESSION_TRUE
   - UNARY_RECEIVER
   - UNDEF_ARGUMENT
+  - UNEXPECTED_BLOCK_ARGUMENT
   - UNEXPECTED_TOKEN_CLOSE_CONTEXT
   - UNEXPECTED_TOKEN_IGNORE
   - UNTIL_TERM

prism/prism.c

@@ -17601,6 +17601,16 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
             pm_arguments_t arguments = { 0 };
             parse_arguments_list(parser, &arguments, false, accepts_command_call);
 
+            // It's possible that we've parsed a block argument through our
+            // call to parse_arguments_list. If we found one, we should mark it
+            // as invalid and destroy it, as we don't have a place for it on the
+            // yield node.
+            if (arguments.block != NULL) {
+                pm_parser_err_node(parser, arguments.block, PM_ERR_UNEXPECTED_BLOCK_ARGUMENT);
+                pm_node_destroy(parser, arguments.block);
+                arguments.block = NULL;
+            }
+
             pm_node_t *node = (pm_node_t *) pm_yield_node_create(parser, &keyword, &arguments.opening_loc, arguments.arguments, &arguments.closing_loc);
             if (!parser->parsing_eval) parse_yield(parser, node);
 

prism/templates/src/diagnostic.c.erb

@@ -317,6 +317,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
     [PM_ERR_TERNARY_EXPRESSION_TRUE]            = { "expected an expression after `?` in the ternary operator", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_UNDEF_ARGUMENT]                     = { "invalid argument being passed to `undef`; expected a bare word, constant, or symbol argument", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_UNARY_RECEIVER]                     = { "unexpected %s, expected a receiver for unary `%c`", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_UNEXPECTED_BLOCK_ARGUMENT]          = { "block argument should not be given", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_UNEXPECTED_TOKEN_CLOSE_CONTEXT]     = { "unexpected %s, assuming it is closing the parent %s", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_UNEXPECTED_TOKEN_IGNORE]            = { "unexpected %s, ignoring it", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_UNTIL_TERM]                         = { "expected an `end` to close the `until` statement", PM_ERROR_LEVEL_SYNTAX },

test/prism/errors_test.rb

@@ -2202,6 +2202,10 @@ module Prism
       refute_error_messages "case (); in [{a:1}, {a:2}]; end"
     end
 
+    def test_unexpected_block
+      assert_error_messages "def foo = yield(&:+)", ["block argument should not be given"]
+    end
+
     private
 
     def assert_errors(expected, source, errors, check_valid_syntax: true)