From 4095e7d2be0ef6426e0cb75a53472f6dc1e5a0af Mon Sep 17 00:00:00 2001
From: Kevin Newton <kddnewton@gmail.com>
Date: Mon, 11 Dec 2023 09:30:24 -0500
Subject: [PATCH] [ruby/prism] Regexp terminator escapes

https://github.com/ruby/prism/commit/42a48a2ba9
---
 prism/prism.c                             | 19 +++++++++++++++++--
 test/prism/snapshots/seattlerb/bug190.txt |  2 +-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/prism/prism.c b/prism/prism.c
index 9922f5772291fd..9bed7b19d8ce32 100644
--- a/prism/prism.c
+++ b/prism/prism.c
@@ -9535,7 +9535,9 @@ parser_lex(pm_parser_t *parser) {
                         case '\r':
                             parser->current.end++;
                             if (peek(parser) != '\n') {
-                                pm_token_buffer_push(&token_buffer, '\\');
+                                if (lex_mode->as.regexp.terminator != '\r') {
+                                    pm_token_buffer_push(&token_buffer, '\\');
+                                }
                                 pm_token_buffer_push(&token_buffer, '\r');
                                 break;
                             }
@@ -9563,7 +9565,20 @@ parser_lex(pm_parser_t *parser) {
                             escape_read(parser, &token_buffer.buffer, PM_ESCAPE_FLAG_REGEXP);
                             break;
                         default:
-                            if (lex_mode->as.regexp.terminator == '/' && peeked == '/') {
+                            if (lex_mode->as.regexp.terminator == peeked) {
+                                // Some characters when they are used as the
+                                // terminator also receive an escape. They are
+                                // enumerated here.
+                                switch (peeked) {
+                                    case '$': case ')': case '*': case '+':
+                                    case '.': case '>': case '?': case ']':
+                                    case '^': case '|': case '}':
+                                        pm_token_buffer_push(&token_buffer, '\\');
+                                        break;
+                                    default:
+                                        break;
+                                }
+
                                 pm_token_buffer_push(&token_buffer, peeked);
                                 parser->current.end++;
                                 break;
diff --git a/test/prism/snapshots/seattlerb/bug190.txt b/test/prism/snapshots/seattlerb/bug190.txt
index ef4411ddb7937a..f7eaefa5c67574 100644
--- a/test/prism/snapshots/seattlerb/bug190.txt
+++ b/test/prism/snapshots/seattlerb/bug190.txt
@@ -8,4 +8,4 @@
             ├── opening_loc: (1,0)-(1,3) = "%r'"
             ├── content_loc: (1,3)-(1,5) = "\\'"
             ├── closing_loc: (1,5)-(1,6) = "'"
-            └── unescaped: "\\'"
+            └── unescaped: "'"