calling join on an Array of BINARY Strings returns UTF-8, may raise Encoding::CompatibilityError.

[dev@…]

### Ruby 1.9.2
s = "a".force_encoding("BINARY")         # => "a"
s.encoding                               # => #<Encoding:ASCII-8BIT>
[s, s].join.encoding                     # => #<Encoding:ASCII-8BIT>

s = "\xA4\x01".force_encoding("BINARY")  # => "\xA4\x01"
s.encoding                               # => #<Encoding:ASCII-8BIT>
[s, s].join.encoding                     # => #<Encoding:ASCII-8BIT>


### MacRuby 0.7 trunk@4494
s = "a".force_encoding("BINARY")         # => "a"  
s.encoding                               # => #<Encoding:ASCII-8BIT>
[s, s].join.encoding                     # => #<Encoding:UTF-8>

s = "\xA4\x01".force_encoding("BINARY")  # => "\xA4\x01"
s.encoding                               # => #<Encoding:ASCII-8BIT>
[s, s].join.encoding                     # Encoding::CompatibilityError: incompatible character encodings: UTF-8 and ASCII-8BIT

[lsansonetti@…]

Indeed, looks like our #join does not honor the operands encoding. Aah, joy.

[lsansonetti@…]

Actually, it looks like MacRuby returns UTF-8 because that's what we use by default. If you add a magic comment to specify UTF-8 ruby 1.9 will behave the same. I am not sure if this is really a bug.

[dev@…]

Cc Me!

[dev@…]

That's not true.

#!/usr/bin/env ruby
# encoding: UTF-8
s = "a".force_encoding("BINARY")
puts s.encoding
puts [s, s].join.encoding
s = "\xA4\x01".force_encoding("BINARY")
puts s.encoding
puts [s, s].join.encoding

Gives me

ASCII-8BIT
ASCII-8BIT
ASCII-8BIT
ASCII-8BIT

With ruby 1.9.2p0 (2010-08-18 revision 29034) [universal.x86_64-darwin10.4.0]

[lsansonetti@…]

The problem seems to be fixed with r4982.