Issue #8445 has been updated by JesseJohnson (Jesse Johnson). I can replicate this in 3.2.2. ---------------------------------------- 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) ---------------------------------------- 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) -- https://bugs.ruby-lang.org/