From: shugo@...
Date: 2015-12-17T02:23:16+00:00
Subject: [ruby-core:72201] [Ruby trunk - Bug #11827] [Feedback] StringIO with set_encoding broken with enabled frozen string literal

Issue #11827 has been updated by Shugo Maeda.

Status changed from Open to Feedback

deepj # wrote:
> I'm not sure if this the following problem is an expected behavior. But I guess, it is a bug when I run the code below. It throws `set_encoding': can't modify frozen String (RuntimeError).
> 
> ~~~
> # frozen_string_literal: true
> 
> io = StringIO.new('')
> io.set_encoding(Encoding::BINARY)
> ~~~
> 
> I wouldn't expect this kind of behavior.

What behavior do you expect?

StringIO is a wrapper to provide IO-like interface for String, so the argument of `StringIO.new` should not be copied.

```ruby
s = "foo"
io = StringIO.new(s)
io.putc(?b)
p s #=> "boo"
```

If you specify writable mode explicitly, you can get an exception earlier:

```ruby
# frozen_string_literal: true

io = StringIO.new("", "w") #=> Errno::EACCESS
```


----------------------------------------
Bug #11827: StringIO with set_encoding broken with enabled frozen string literal
https://bugs.ruby-lang.org/issues/11827#change-55612

* Author: deepj #
* Status: Feedback
* Priority: Normal
* Assignee: 
* ruby -v: ruby 2.3.0preview2 (2015-12-11 trunk 53028) [x86_64-darwin15]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
I'm not sure if this the following problem is an expected behavior. But I guess, it is a bug when I run the code below. It throws `set_encoding': can't modify frozen String (RuntimeError).

~~~
# frozen_string_literal: true

io = StringIO.new('')
io.set_encoding(Encoding::BINARY)
~~~

I wouldn't expect this kind of behavior.




-- 
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