Issue #8342 has been reported by leocassarani (Leo Cassarani).

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Bug #8342: IO.readlines ignores Encoding.default_internal if Encoding.default_external is ASCII-8BIT
https://bugs.ruby-lang.org/issues/8342

Author: leocassarani (Leo Cassarani)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 1.9.3
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


Under normal circumstances, IO.readlines will transcode from Encoding.default_external to Encoding.default_internal:

File.open('hi', 'w') { |f| f.puts "hello\n" }
Encoding.default_external = Encoding::US_ASCII
Encoding.default_internal = Encoding::UTF_8
puts IO.readlines('hi').first.encoding
#=> UTF-8

However, when Encoding.default_external is set to ASCII-8BIT, IO.readlines will always use ASCII-8BIT, regardless of what Encoding.default_internal is set to:

File.open('hi', 'w') { |f| f.puts "hello\n" }
Encoding.default_external = Encoding::ASCII_8BIT
Encoding.default_internal = Encoding::UTF_8
puts IO.readlines('hi').first.encoding
#=> ASCII-8BIT

Using IO#gets instead of IO.readlines will produce the same behaviour.


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