From 9b24e6ae9f35739f04b29ca13f90f1242e2296d8 Mon Sep 17 00:00:00 2001
From: Ilya Bylich <ibylich@gmail.com>
Date: Thu, 8 Jul 2021 19:50:34 +0300
Subject: [PATCH] + lexer.rl: reject `\u` after control/meta escape chars.
 (#807)

This commit tracks upstream commit ruby/ruby@110f242.
---
 lib/parser/lexer.rl |  5 +++++
 test/test_lexer.rb  | 40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+)

diff --git a/lib/parser/lexer.rl b/lib/parser/lexer.rl
index 5e370c95d..8574f95cc 100644
--- a/lib/parser/lexer.rl
+++ b/lib/parser/lexer.rl
@@ -705,6 +705,11 @@ class Parser::Lexer
 
   action unescape_char {
     codepoint = @source_pts[p - 1]
+
+    if @version >= 30 && (codepoint == 117 || codepoint == 85) # 'u' or 'U'
+      diagnostic :fatal, :invalid_escape
+    end
+
     if (@escape = ESCAPES[codepoint]).nil?
       @escape = encode_escape(@source_buffer.slice(p - 1))
     end
diff --git a/test/test_lexer.rb b/test/test_lexer.rb
index 54db8bb20..9074ccc27 100644
--- a/test/test_lexer.rb
+++ b/test/test_lexer.rb
@@ -3614,4 +3614,44 @@ def refute_scanned_numbered_parameter(input, message = nil)
     end
   end
 
+  def test_meta_escape_slash_u__before_30
+    setup_lexer(27)
+    assert_scanned('"\c\u0000"',
+                    :tSTRING, "\u00150000", [0, 10])
+    assert_scanned('"\c\U0000"',
+                    :tSTRING, "\u00150000", [0, 10])
+
+    assert_scanned('"\C-\u0000"',
+                    :tSTRING, "\u00150000", [0, 11])
+    assert_scanned('"\C-\U0000"',
+                    :tSTRING, "\u00150000", [0, 11])
+
+    assert_scanned('"\M-\u0000"',
+                    :tSTRING, "\xF50000", [0, 11])
+    assert_scanned('"\M-\U0000"',
+                    :tSTRING, "\xD50000", [0, 11])
+  end
+
+  def refute_scanned_meta_escape_slash_u(input)
+    setup_lexer(30)
+    source_buffer = Parser::Source::Buffer.new('(refute_scanned_meta_escape_slash_u)', source: input)
+    @lex.source_buffer = source_buffer
+
+    err = assert_raises Parser::SyntaxError do
+      @lex.advance
+    end
+
+    assert_equal :invalid_escape, err.diagnostic.reason
+  end
+
+  def test_meta_escape_slash_u__after_30
+    refute_scanned_meta_escape_slash_u('"\c\u0000"')
+    refute_scanned_meta_escape_slash_u('"\c\U0000"')
+
+    refute_scanned_meta_escape_slash_u('"\C-\u0000"')
+    refute_scanned_meta_escape_slash_u('"\C-\U0000"')
+
+    refute_scanned_meta_escape_slash_u('"\M-\u0000"')
+    refute_scanned_meta_escape_slash_u('"\M-\U0000"')
+  end
 end