From 65ae61cb4f513a38a0c1660ae75268adf30b976d Mon Sep 17 00:00:00 2001
From: Kevin Newton <kddnewton@gmail.com>
Date: Wed, 17 Aug 2022 12:00:48 -0400
Subject: [PATCH] Handle regexp without ending better

---
 lib/syntax_tree/parser.rb | 11 +++++++++--
 test/parser_test.rb       |  7 +++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/syntax_tree/parser.rb b/lib/syntax_tree/parser.rb
index 3824b6b3..8af0b8ed 100644
--- a/lib/syntax_tree/parser.rb
+++ b/lib/syntax_tree/parser.rb
@@ -2837,14 +2837,21 @@ def on_regexp_end(value)
     # :call-seq:
     #   on_regexp_literal: (
     #     RegexpContent regexp_content,
-    #     RegexpEnd ending
+    #     (nil | RegexpEnd) ending
     #   ) -> RegexpLiteral
     def on_regexp_literal(regexp_content, ending)
+      location = regexp_content.location
+
+      if ending.nil?
+        message = "Cannot find expected regular expression ending"
+        raise ParseError.new(message, *find_token_error(location))
+      end
+
       RegexpLiteral.new(
         beginning: regexp_content.beginning,
         ending: ending.value,
         parts: regexp_content.parts,
-        location: regexp_content.location.to(ending.location)
+        location: location.to(ending.location)
       )
     end
 
diff --git a/test/parser_test.rb b/test/parser_test.rb
index d0c475c1..fbff8ec2 100644
--- a/test/parser_test.rb
+++ b/test/parser_test.rb
@@ -41,6 +41,13 @@ def test_errors_on_missing_end_with_location
       assert_equal(4, error.column)
     end
 
+    def test_errors_on_missing_regexp_ending
+      error =
+        assert_raises(Parser::ParseError) { SyntaxTree.parse("a =~ /foo") }
+
+      assert_equal(5, error.column)
+    end
+
     def test_errors_on_missing_token_without_location
       assert_raises(Parser::ParseError) { SyntaxTree.parse(":\"foo") }
     end