Issue #20919 has been reported by javanthropus (Jeremy Bopp). ---------------------------------------- Bug #20919: IO#seek does not clear the character buffer in some cases while transcoding https://bugs.ruby-lang.org/issues/20919 * Author: javanthropus (Jeremy Bopp) * Status: Open * ruby -v: ruby 3.4.0dev (2024-11-28T12:38:16Z master 3af1a04741) +PRISM [x86_64-linux] * Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN ---------------------------------------- When transcoding characters, `IO#seek` only clears the internal character buffer if `IO#getc` is called first: ```ruby require 'tempfile' Tempfile.open(encoding: 'utf-8:utf-16le') do |f| f.write('0123456789') f.rewind f.ungetc('a'.encode('utf-16le')) # Character buffer WILL NOT be cleared f.seek(2, :SET) f.getc # => 'a'.encode('utf-16le'); should be '2'.encode('utf-16le') end Tempfile.open(encoding: 'utf-8:utf-16le') do |f| f.write('0123456789') f.rewind # Added a call to #getc here f.getc f.ungetc('a'.encode('utf-16le')) # Character buffer WILL be cleared now f.seek(2, :SET) f.getc # => '2'.encode('utf-16le') end ``` -- https://bugs.ruby-lang.org/