[Bug #19547] Add token for unescaped backslash

This token is exposed only when `RubyVM::AbstractSyntaxTree` with
`keep_tokens` option.

1 files changed, 1 insertions, 0 deletions

diff --git a/parse.y b/parse.y
index 4b44f7e440..f0b86ac9ad 100644
--- a/parse.y
+++ b/parse.y
@@ -495,6 +495,7 @@ parser_token2id(enum yytokentype tok)
       TOKEN2ID2(']', "]");
       TOKEN2ID2('(', "(");
       TOKEN2ID2(')', ")");
+      TOKEN2ID2('\\', "backslash");
       TOKEN2ID(keyword_class);
       TOKEN2ID(keyword_module);
       TOKEN2ID(keyword_def);