Match error messages for invalid instance/class variables

config.yml

@@ -47,6 +47,7 @@ errors:
   - CLASS_SUPERCLASS
   - CLASS_TERM
   - CLASS_UNEXPECTED_END
+  - CLASS_VARIABLE_BARE
   - CONDITIONAL_ELSIF_PREDICATE
   - CONDITIONAL_IF_PREDICATE
   - CONDITIONAL_PREDICATE_TERM
@@ -119,6 +120,7 @@ errors:
   - INCOMPLETE_VARIABLE_CLASS_3_3_0
   - INCOMPLETE_VARIABLE_INSTANCE
   - INCOMPLETE_VARIABLE_INSTANCE_3_3_0
+  - INSTANCE_VARIABLE_BARE
   - INVALID_CHARACTER
   - INVALID_ENCODING_MAGIC_COMMENT
   - INVALID_FLOAT_EXPONENT

src/prism.c

@@ -9022,14 +9022,17 @@ lex_at_variable(pm_parser_t *parser) {
         while (parser->current.end < parser->end && (width = char_is_identifier(parser, parser->current.end)) > 0) {
             parser->current.end += width;
         }
-    } else {
+    } else if (parser->current.end < parser->end && pm_char_is_decimal_digit(*parser->current.end)) {
         pm_diagnostic_id_t diag_id = (type == PM_TOKEN_CLASS_VARIABLE) ? PM_ERR_INCOMPLETE_VARIABLE_CLASS : PM_ERR_INCOMPLETE_VARIABLE_INSTANCE;
         if (parser->version == PM_OPTIONS_VERSION_CRUBY_3_3_0) {
             diag_id = (type == PM_TOKEN_CLASS_VARIABLE) ? PM_ERR_INCOMPLETE_VARIABLE_CLASS_3_3_0 : PM_ERR_INCOMPLETE_VARIABLE_INSTANCE_3_3_0;
         }
 
         size_t width = parser->encoding->char_width(parser->current.end, parser->end - parser->current.end);
         PM_PARSER_ERR_TOKEN_FORMAT(parser, parser->current, diag_id, (int) ((parser->current.end + width) - parser->current.start), (const char *) parser->current.start);
+    } else {
+        pm_diagnostic_id_t diag_id = (type == PM_TOKEN_CLASS_VARIABLE) ? PM_ERR_CLASS_VARIABLE_BARE : PM_ERR_INSTANCE_VARIABLE_BARE;
+        pm_parser_err_token(parser, &parser->current, diag_id);
     }
 
     // If we're lexing an embedded variable, then we need to pop back into the

templates/src/diagnostic.c.erb

@@ -132,6 +132,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
     [PM_ERR_CLASS_SUPERCLASS]                   = { "expected a superclass after `<`", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_CLASS_TERM]                         = { "expected an `end` to close the `class` statement", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_CLASS_UNEXPECTED_END]               = { "unexpected `end`, expecting ';' or '\\n'", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_CLASS_VARIABLE_BARE]                = { "'@@' without identifiers is not allowed as a class variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_CONDITIONAL_ELSIF_PREDICATE]        = { "expected a predicate expression for the `elsif` statement", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_CONDITIONAL_IF_PREDICATE]           = { "expected a predicate expression for the `if` statement", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_CONDITIONAL_PREDICATE_TERM]         = { "expected `then` or `;` or '\\n'", PM_ERROR_LEVEL_SYNTAX },
@@ -203,6 +204,7 @@ static const pm_diagnostic_data_t diagnostic_messages[PM_DIAGNOSTIC_ID_MAX] = {
     [PM_ERR_INCOMPLETE_VARIABLE_CLASS]          = { "'%.*s' is not allowed as a class variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INCOMPLETE_VARIABLE_INSTANCE_3_3_0] = { "`%.*s' is not allowed as an instance variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INCOMPLETE_VARIABLE_INSTANCE]       = { "'%.*s' is not allowed as an instance variable name", PM_ERROR_LEVEL_SYNTAX },
+    [PM_ERR_INSTANCE_VARIABLE_BARE]             = { "'@' without identifiers is not allowed as an instance variable name", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_FLOAT_EXPONENT]             = { "invalid exponent", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_NUMBER_BINARY]              = { "invalid binary number", PM_ERROR_LEVEL_SYNTAX },
     [PM_ERR_INVALID_NUMBER_DECIMAL]             = { "invalid decimal number", PM_ERROR_LEVEL_SYNTAX },