[ruby-core:56071] [ruby-trunk - Bug #8653][Open] Unexpected result of String#succ with utf-16 and utf-32 string.

Issue #8653 has been reported by phasis68 (Heesob Park).

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Bug #8653: Unexpected result of String#succ with utf-16 and utf-32 string.
https://bugs.ruby-lang.org/issues/8653

Author: phasis68 (Heesob Park)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 2.1.0dev (2013-07-17 trunk 42011) [i386-mingw32]
Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN


I found the result of String#succ of UTF-16LE encoded string is incorrect. 

As a result, Range of UTF-16LE encoded string show some unexpected behavior.


C:\work>irb
irb(main):001:0> a = 'A'.encode('UTF-16LE')
=> "A"
irb(main):002:0> b = 'B'.encode('UTF-16LE')
=> "B"
irb(main):003:0> a.succ
=> "\u0141"
irb(main):004:0> r = a..b
=> "A".."B"
irb(main):005:0> r.to_s
=> "A\u2E2EB"
irb(main):006:0> r.count
=> 3
irb(main):007:0> r.to_a
=> ["A", "\u0141", "\u0241"]
irb(main):008:0> r.include?(b)
=> false
irb(main):009:0> a = 'A'.encode('UTF-32LE')
=> "A"
irb(main):010:0> b = 'B'.encode('UTF-32LE')
=> "B"
irb(main):011:0> a.succ
=> "\u{1000041}"
irb(main):012:0> r = a..b
=> "A".."B"
irb(main):013:0> r.to_s
=> "A\u{422E2E}\x00\x00"
irb(main):014:0> r.count
=> 16777217
irb(main):015:0> r.to_a
[FATAL] failed to allocate memory

C:\work>


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