ripper/lexer.rb: nested indented heredoc

* ext/ripper/lib/ripper/lexer.rb (on_heredoc_dedent): insert
  stripped leading spaces as `on_ignored_sp` elements, so that the
  original source can be reconsructed.
  [ruby-core:80977] [Bug #13536]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58584 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 20 insertions, 1 deletions

diff --git a/ext/ripper/lib/ripper/lexer.rb b/ext/ripper/lib/ripper/lexer.rb
index 350b513c25..63dcf85132 100644
--- a/ext/ripper/lib/ripper/lexer.rb
+++ b/ext/ripper/lib/ripper/lexer.rb
@@ -66,13 +66,20 @@ class Ripper
     private
 
     def on_heredoc_dedent(v, w)
-      @buf.last.each do |e|
+      ignored_sp = []
+      heredoc = @buf.last
+      heredoc.each_with_index do |e, i|
         if Elem === e and e.event == :on_tstring_content
+          tok = e.tok.dup if w > 0 and /\A\s/ =~ e.tok
           if (n = dedent_string(e.tok, w)) > 0
+            ignored_sp << [i, Elem.new(e.pos.dup, :on_ignored_sp, tok[0, n])]
             e.pos[1] += n
           end
         end
       end
+      ignored_sp.reverse_each do |i, e|
+        heredoc[i, 0] = [e]
+      end
       v
     end
 
diff --git a/test/ripper/test_lexer.rb b/test/ripper/test_lexer.rb
index 2ec66cd592..72b7f1b5fd 100644
--- a/test/ripper/test_lexer.rb
+++ b/test/ripper/test_lexer.rb
@@ -20,5 +20,16 @@ class TestRipper::Lexer < Test::Unit::TestCase
     D
     E
     assert_equal(str, Ripper.tokenize(str).join(""), bug)
+
+    str = <<~'E'
+    <<~"D"
+    #{
+    <<~"B"
+      this must be a valid ruby
+    B
+    }
+    D
+    E
+    assert_equal(str, Ripper.tokenize(str).join(""), bug)
   end
 end
diff --git a/test/ripper/test_scanner_events.rb b/test/ripper/test_scanner_events.rb
index 027d56d1e6..ef49fc18ba 100644
--- a/test/ripper/test_scanner_events.rb
+++ b/test/ripper/test_scanner_events.rb
@@ -105,6 +105,7 @@ class TestRipper::ScannerEvents < Test::Unit::TestCase
                  Ripper.lex("1r\n2i\n3ri\n4.2r\n5.6ri")
      assert_equal [[[1, 0], :on_heredoc_beg, "<<~EOS"],
                    [[1, 6], :on_nl, "\n"],
+                   [[2, 0], :on_ignored_sp, "  "],
                    [[2, 2], :on_tstring_content, "heredoc\n"],
                    [[3, 0], :on_heredoc_end, "EOS"]
                  ],