Issue #20389 has been reported by mdalessio (Mike Dalessio). ---------------------------------------- Bug #20389: Issue with chilled strings and mutability after 12be40ae https://bugs.ruby-lang.org/issues/20389 * 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 ---------------------------------------- Commit 12be40ae introduced the concept of "chilled" strings when code is compiled with frozen-string-literals not explicitly enabled or disabled. I believe I've found a related bug, which I've bisected to this commit. This reproduction has been simplified from a failing test case in the `http-cookie` gem: ``` ruby puts RUBY_DESCRIPTION re = %r{.(?<thing>.*)} input = "x/dir[]/file.html" match = re.match(input) # => "#<MatchData \"x/dir[]/file.html\" thing:\"/dir[]/file.html\">" thing = match[:thing] puts "before: #{thing.inspect}" input[match.begin(:thing)...match.end(:thing)] = "/dir%5B%5D/file.html" puts "after : #{thing.inspect}" exit 1 unless thing == "/dir[]/file.html" ``` Ruby 3.3.0 and earlier is fine: ``` $ ruby ./issue-chilled-strings.rb ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [x86_64-linux] before: "/dir[]/file.html" after : "/dir[]/file.html" ``` Master with frozen string explicitly disabled passes: ``` $ ruby --disable-frozen-string-literal ./issue-chilled-strings.rb ruby 3.4.0dev (2024-03-23T16:40:17Z master 8265a7531f) [x86_64-linux] before: "/dir[]/file.html" after : "/dir[]/file.html" ``` Master with frozen strings explicitly enabled fails as expected: ``` $ ruby --enable-frozen-string-literal ./issue-chilled-strings.rb ruby 3.4.0dev (2024-03-23T16:40:17Z master 8265a7531f) [x86_64-linux] before: "/dir[]/file.html" ./issue-chilled-strings.rb:12:in 'String#[]=': can't modify frozen String: "x/dir[]/file.html" (FrozenError) from ./issue-chilled-strings.rb:12:in '<main>' ``` But master with no frozen string setting ("chilled") fails, and modifies what should be a frozen string: ``` $ ruby ./issue-chilled-strings.rb ruby 3.4.0dev (2024-03-23T16:40:17Z master 8265a7531f) [x86_64-linux] before: "/dir[]/file.html" after : "/dir%5B%5D/file." ``` I believe in this case, the chilled warning should be emitted, but then the frozen string should not be modified. -- https://bugs.ruby-lang.org/