Issue #20390 has been reported by mdalessio (Mike Dalessio). ---------------------------------------- Bug #20390: Issue with StringIO and chilled strings https://bugs.ruby-lang.org/issues/20390 * Author: mdalessio (Mike Dalessio) * Status: Open * ruby -v: ruby 3.4.0dev (2024-03-23T16:40:17Z master 8265a7531f) [x86_64-linux] * Backport: 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- StringIO doesn't appear to handle chilled strings in a backwards-compatible way after 12be40ae ```ruby require "stringio" sio = StringIO.new("") sio.write("hello") ``` When not specifying a value for `frozen-string-literal`, the empty string is chilled so I would expect to get a warning but also expect the write to complete. Instead, the write fails as if the string is frozen: ``` ruby 3.4.0dev (2024-03-23T16:40:17Z master 8265a7531f) [x86_64-linux] ./issue-stringio-frozen.rb:8:in 'StringIO#write': not opened for writing (IOError) from ./issue-stringio-frozen.rb:8:in '<main>' ``` cc @byroot @etienne -- https://bugs.ruby-lang.org/