[ruby-dev:52058] [Ruby master Bug#8445] IO.open and IO#set_enconding does not support :fallback option

["JesseJohnson (Jesse Johnson) via ruby-dev" <ruby-dev@ml.ruby-lang.org>]

Issue #8445 has been updated by JesseJohnson (Jesse Johnson).


I can replicate this in 3.2.2.

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Bug #8445: IO.open and IO#set_enconding does not support :fallback option
https://bugs.ruby-lang.org/issues/8445#change-105299

* Author: pjmtdw (Haruhiro Yoshimoto)
* Status: Assigned
* Priority: Normal
* Assignee: akr (Akira Tanaka)
* ruby -v: trunk(ruby 2.1.0dev)
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RubyDoc says that `IO.open` and `IO#set_encoding` supports optional argument defined in `String#encode`.
http://ruby-doc.org/core-2.0/IO.html#method-c-new-label-Options
In fact, `:invalid, :undef and :replace` works as expected.

However, `:fallback` option does not work neither for `IO.open` and `IO#set_encoding`.
Following is the example code which does not work.
`f(x)` is never called even if hoge.txt contains non convertible character.

```ruby
File.open("./hoge.txt","r:Shift_JIS:utf-8", :fallback => lambda{|x|f(x)}){|f|
  ...
}
File.open("./hoge.txt"){|f|
  f.set_encoding("Shift_JIS","utf-8",:fallback => lambda{|x|f(x)})
  ...
}
```

I Think this is because `fill_cbuf()` in `io.c` calls `rb_econv_convert()` from `transcode.c` directly.
On the other hand, `fallback_func` is called in `transcode_loop()`, which is called by `str_encode()`. 

Since `transcode_loop()` also calls `rb_econv_convert()`, I wrote a small patch which moves some codes from
`transcode_loop()` to `rb_econv_convert()` to fix the problem.

The attached file is the patch. Hope this helps.


---Files--------------------------------
support-fallback-for-io.patch (3.9 KB)


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