Bug #10285: StringIO with encodings broken due to #9769

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: 2.1.3
• Backport: 2.0.0: DONE, 2.1: DONE

[dbussink (Dirkjan Bussink)]

It looks like the change in https://bugs.ruby-lang.org/issues/9769 resulted in a behavior change with how StringIO works with different encodings.

The following snippet is broken and now raises:

test_string_io_encoding.rb:8:in `write': incompatible character encodings: ASCII-8BIT and Windows-1252 (Encoding::CompatibilityError)
	from test_string_io_encoding.rb:8:in `<main>'

require 'stringio'

io = StringIO.new
io.set_encoding(Encoding::ASCII_8BIT)
io.write("quz \x83 mat".force_encoding(Encoding::ASCII_8BIT))

str = "foo \x97 bar".force_encoding(Encoding::WINDOWS_1252)
io.write(str)

p io.string

What is the intended behavior here? If I change the code to not set the encoding on the StringIO object, it does work somehow:

require 'stringio'

io = StringIO.new
io.write("quz \x83 mat".force_encoding(Encoding::ASCII_8BIT))

str = "foo \x97 bar".force_encoding(Encoding::WINDOWS_1252)
io.write(str)

p io.string

In this case it sees io.string as UTF-8 encoded, but this is invalid. It does allow the second StringIO#write here though.

[dbussink (Dirkjan Bussink)]

As another data point, I also tried this with writing to a file which seems to work:

File.open("out.txt", :mode => "w", :encoding => Encoding::ASCII_8BIT) do |f|
  str1 = "quz \x83 mat".force_encoding(Encoding::ASCII_8BIT)
  f.write(str1)
  str2 = "foo \x97 bar".force_encoding(Encoding::WINDOWS_1252)
  f.write(str2)
end

p File.read("out.txt")

[usa (Usaku NAKAMURA)]

• Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.0.0: REQUIRED, 2.1: REQUIRED

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

Applied in changeset r47716.

---

stringio.c: ASCII-8BIT StringIO rejects no encodings

• ext/stringio/stringio.c (strio_write): ASCII-8BIT StringIO
  should be writable any encoding strings, without conversion.
  [ruby-core:65240] [Bug #10285]

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 2.0.0: REQUIRED, 2.1: REQUIRED to 2.0.0: REQUIRED, 2.1: DONE

Backported into ruby_2_1 at r47982.

[usa (Usaku NAKAMURA)]

• Backport changed from 2.0.0: REQUIRED, 2.1: DONE to 2.0.0: DONE, 2.1: DONE

Backported into ruby_2_0_0 at r47988.