Fix mixed encoding in heredoc

Heredocs are parsed line-by-line, so we need to keep track of the
temporary encoding of the string.  Previously, a heredoc would
only detect mixed encoding errors if they were on the same line,
this changes things so they will be caught on different lines.

Fixes [Bug #15839]

1 files changed, 29 insertions, 0 deletions

diff --git a/test/ruby/test_syntax.rb b/test/ruby/test_syntax.rb
index c9eaa5af6d..7bf1e0e43c 100644
--- a/test/ruby/test_syntax.rb
+++ b/test/ruby/test_syntax.rb
@@ -774,6 +774,35 @@ eom
     assert_equal("\n0\n1", eval("<<~0 '1'\n \n0\#{}\n0"))
   end
 
+  def test_heredoc_mixed_encoding
+    assert_syntax_error(<<-'HEREDOC', 'UTF-8 mixed within Windows-31J source')
+      #encoding: cp932
+      <<-TEXT
+      \xe9\x9d\u1234
+      TEXT
+    HEREDOC
+    assert_syntax_error(<<-'HEREDOC', 'UTF-8 mixed within Windows-31J source')
+      #encoding: cp932
+      <<-TEXT
+      \xe9\x9d
+      \u1234
+      TEXT
+    HEREDOC
+    assert_syntax_error(<<-'HEREDOC', 'UTF-8 mixed within Windows-31J source')
+      #encoding: cp932
+      <<-TEXT
+      \u1234\xe9\x9d
+      TEXT
+    HEREDOC
+    assert_syntax_error(<<-'HEREDOC', 'UTF-8 mixed within Windows-31J source')
+      #encoding: cp932
+      <<-TEXT
+      \u1234
+      \xe9\x9d
+      TEXT
+    HEREDOC
+  end
+
   def test_lineno_operation_brace_block
     expected = __LINE__ + 1
     actual = caller_lineno\