Issue #7282 has been reported by headius (Charles Nutter).

----------------------------------------
Bug #7282: Invalid UTF-8 from emoji allowed through silently
https://bugs.ruby-lang.org/issues/7282

Author: headius (Charles Nutter)
Status: Open
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: 2.0.0


On my system, where the default encoding is UTF-8, the following should not parse:

ruby-2.0.0 -e 'p "Hello, \x96 world!\"}'

But it does. And it is apparently marked as "ok" as far as code range goes, because encoding to UTF-8 does not catch the problem:

system ~/projects/jruby $ ruby-1.9.3 -e 'p "{\"sample\": \"Hello, \x96 world!\"}".encode("UTF-8")'
"{\"sample\": \"Hello, \x96 world!\"}"

system ~/projects/jruby $ ruby-2.0.0 -e 'p "{\"sample\": \"Hello, \x96 world!\"}".encode("UTF-8")'
"{\"sample\": \"Hello, \x96 world!\"}"

Nor does character-walking:

system ~/projects/jruby $ ruby-1.9.3 -e '"Hello, \x96 world!".each_char {|x| print x}'
Hello, ? world!
system ~/projects/jruby $ ruby-2.0.0 -e '"Hello, \x96 world!".each_char {|x| print x}'
Hello, ? world!

Nor does []:

system ~/projects/jruby $ ruby-1.9.3 -e 'p "Hello, \x96 world!"[7]'
"\x96"

system ~/projects/jruby $ ruby-1.9.3 -e 'p "Hello, \x96 world!"[8]'
" "

system ~/projects/jruby $ ruby-2.0.0 -e 'p "Hello, \x96 world!"[7]'
"\x96"

system ~/projects/jruby $ ruby-2.0.0 -e 'p "Hello, \x96 world!"[8]'
" "

But the malformed String does get caught by transcoding to UTF-16:

system ~/projects/jruby $ ruby-1.9.3 -e 'p "{\"sample\": \"Hello, \x96 world!\"}".encode("UTF-16")'
-e:1:in `encode': "\x96" on UTF-8 (Encoding::InvalidByteSequenceError)
	from -e:1:in `<main>'

system ~/projects/jruby $ ruby-2.0.0 -e 'p "{\"sample\": \"Hello, \x96 world!\"}".encode("UTF-16")'
-e:1:in `encode': "\x96" on UTF-8 (Encoding::InvalidByteSequenceError)
	from -e:1:in `<main>'

Or by doing a simple regexp match:

system ~/projects/jruby $ ruby-1.9.3 -e '"Hello, \x96 world!".match /.+/'
-e:1:in `match': invalid byte sequence in UTF-8 (ArgumentError)
	from -e:1:in `match'
	from -e:1:in `<main>'

system ~/projects/jruby $ ruby-2.0.0 -e '"Hello, \x96 world!".match /.+/'
-e:1:in `match': invalid byte sequence in UTF-8 (ArgumentError)
	from -e:1:in `match'
	from -e:1:in `<main>'

And of course I am ignoring the fact that it should never have parsed to begin with.

This kind of inconsistency in rejecting malformed UTF-8 does not inspire a lot of confidence.

JRuby allows it through the parser (this is a bug) but does fail in other places because the string is malformed.


-- 
http://bugs.ruby-lang.org/