merge revision(s) b84b253a69537a14e4854e17b6d94ae75c2af050: [Backport #17547]

	Fix Ripper with heredoc.

	---
	 ext/ripper/lib/ripper/lexer.rb |  1 +
	 test/ripper/test_lexer.rb      | 10 ++++++++++
	 2 files changed, 11 insertions(+)

1 files changed, 10 insertions, 0 deletions

diff --git a/test/ripper/test_lexer.rb b/test/ripper/test_lexer.rb
index f8e751da53..3eaeb8fefa 100644
--- a/test/ripper/test_lexer.rb
+++ b/test/ripper/test_lexer.rb
@@ -90,6 +90,16 @@ class TestRipper::Lexer < Test::Unit::TestCase
     assert_equal expect, Ripper.lex(src).map {|e| e[1]}
   end
 
+  def test_stack_at_on_heredoc_beg
+    src = "a <<b"
+    expect = %I[
+      on_ident
+      on_sp
+      on_heredoc_beg
+    ]
+    assert_equal expect, Ripper.lex(src).map {|e| e[1]}
+  end
+
   def test_slice
     assert_equal "string\#{nil}\n",
       Ripper.slice(%(<<HERE\nstring\#{nil}\nHERE), "heredoc_beg .*? nl $(.*?) heredoc_end", 1)