[ruby/prism] Require a delimiter for singleton classes

https://github.com/ruby/prism/commit/fd58d6a9ea

prism/config.yml

@@ -107,6 +107,7 @@ errors:
   - EXPECT_RPAREN
   - EXPECT_RPAREN_AFTER_MULTI
   - EXPECT_RPAREN_REQ_PARAMETER
+  - EXPECT_SINGLETON_CLASS_DELIMITER
   - EXPECT_STRING_CONTENT
   - EXPECT_WHEN_DELIMITER
   - EXPRESSION_BARE_HASH

prism/prism.c

@@ -18966,7 +18966,9 @@ parse_expression_prefix(pm_parser_t *parser, pm_binding_power_t binding_power, b
                 pm_node_t *expression = parse_value_expression(parser, PM_BINDING_POWER_COMPOSITION, true, false, PM_ERR_EXPECT_EXPRESSION_AFTER_LESS_LESS, (uint16_t) (depth + 1));
 
                 pm_parser_scope_push(parser, true);
-                accept2(parser, PM_TOKEN_NEWLINE, PM_TOKEN_SEMICOLON);
+                if (!match2(parser, PM_TOKEN_NEWLINE, PM_TOKEN_SEMICOLON)) {
+                    PM_PARSER_ERR_TOKEN_FORMAT(parser, parser->current, PM_ERR_EXPECT_SINGLETON_CLASS_DELIMITER, pm_token_type_human(parser->current.type));
+                }
 
                 pm_node_t *statements = NULL;
                 if (!match4(parser, PM_TOKEN_KEYWORD_RESCUE, PM_TOKEN_KEYWORD_ENSURE, PM_TOKEN_KEYWORD_ELSE, PM_TOKEN_KEYWORD_END)) {

prism/templates/src/diagnostic.c.erb

@@ -190,6 +190,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
     [PM_ERR_EXPECT_RPAREN]                      = { "expected a matching `)`", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_EXPECT_RPAREN_AFTER_MULTI]          = { "expected a `)` after multiple assignment", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_EXPECT_RPAREN_REQ_PARAMETER]        = { "expected a `)` to end a required parameter", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_EXPECT_SINGLETON_CLASS_DELIMITER]   = { "unexpected %s; expected a newline or a ';' after the singleton class", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_EXPECT_STRING_CONTENT]              = { "expected string content after opening string delimiter", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_EXPECT_WHEN_DELIMITER]              = { "expected a delimiter after the predicates of a `when` clause", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_EXPRESSION_BARE_HASH]               = { "unexpected bare hash in expression", PM_ERROR_LEVEL_SYNTAX },

test/prism/errors/singleton_class_delimiter.txt

@@ -0,0 +1,3 @@
+class <<self rand end
+             ^~~~ unexpected local variable or method; expected a newline or a ';' after the singleton class
+