Treat encodings in exception correctly

lib/irb.rb

@@ -590,9 +590,15 @@ def eval_input
       end
     end
 
-    def convert_invalid_byte_sequence(str)
-      str = str.force_encoding(Encoding::ASCII_8BIT)
-      conv = Encoding::Converter.new(Encoding::ASCII_8BIT, Encoding::UTF_8)
+    def convert_invalid_byte_sequence(str, enc)
+      str.force_encoding(enc)
+      str.scrub { |c|
+        c.bytes.map{ |b| "\\x#{b.to_s(16).upcase}" }.join
+      }
+    end
+
+    def encode_with_invalid_byte_sequence(str, enc)
+      conv = Encoding::Converter.new(str.encoding, enc)
       dst = String.new
       begin
         ret = conv.primitive_convert(str, dst)
@@ -640,7 +646,8 @@ def handle_exception(exc)
           message = exc.full_message(order: :top)
           order = :top
         end
-        message = convert_invalid_byte_sequence(message)
+        message = convert_invalid_byte_sequence(message, exc.message.encoding)
+        message = encode_with_invalid_byte_sequence(message, IRB.conf[:LC_MESSAGES].encoding) if message.encoding != IRB.conf[:LC_MESSAGES].encoding
         message = message.gsub(/((?:^\t.+$\n)+)/)  { |m|
           case order
           when :top

test/irb/test_raise_no_backtrace_exception.rb

@@ -21,5 +21,30 @@ def test_raise_exception_with_invalid_byte_sequence
         raise StandardError, "A\\xf3B"
       IRB
     end
+
+    def test_raise_exception_with_different_encoding_containing_invalid_byte_sequence
+      skip if RUBY_ENGINE == 'truffleruby'
+      backup_home = ENV["HOME"]
+      Dir.mktmpdir("test_irb_raise_no_backtrace_exception_#{$$}") do |tmpdir|
+        ENV["HOME"] = tmpdir
+
+        bundle_exec = ENV.key?('BUNDLE_GEMFILE') ? ['-rbundler/setup'] : []
+        File.open('euc.rb', 'w') do |f|
+          f.write(<<~EOF)
+            # encoding: euc-jp
+
+            def raise_euc_with_invalid_byte_sequence
+              raise "\xA4\xA2\\xFF"
+            end
+          EOF
+        end
+        assert_in_out_err(bundle_exec + %w[-rirb -W0 -e ENV[%(LC_ALL)]=%(ja_JP.UTF-8) -e ENV[%(LANG)]=%(ja_JP.UTF-8) -e IRB.start(__FILE__) -- -f --], <<~IRB, /`raise_euc_with_invalid_byte_sequence': あ\\xFF \(RuntimeError\)/, [])
+          require_relative 'euc'
+          raise_euc_with_invalid_byte_sequence
+        IRB
+      end
+    ensure
+      ENV["HOME"] = backup_home
+    end
   end
 end