Sample

Work out which stdlib libraries Ruby 3.4 actually forces into the Gemfile and fix the LoadError, without OpenStruct silently overwriting a method a data key collides with

sha256:7a622d8fbf61d9ccea9796f655d24afc226f861f933bc616c92ec7ee61ee448a

PUBLISHED L3_CONTRACT_PASS MIT-0

Case

Goal: Work out which stdlib libraries Ruby 3.4 actually forces into the Gemfile and fix the LoadError, without OpenStruct silently overwriting a method a data key collides with FIX
Packages: ostruct 0.6.3 set 1.1.3 abbrev 0.1.2
Environment: ruby 3
Created: 2026-08-14T20:29:58Z

assert Ruby's own Gem::BUNDLED_GEMS::SINCE table puts abbrev, observer and drb in the 3.4.0 wave, ostruct, benchmark and logger in the 4.0.0 wave, and set on no wave at all
assert a library from the wave that already landed raises LoadError naming it unless the Gemfile declares it, while the declared one loads and lands its Array monkeypatch
assert Ruby emits the add-it-to-your-Gemfile notice through Warning.warn and still raises the LoadError in the same run
assert a library from the next wave loads without a Gemfile entry but warns about 4.0.0, and stays absent from the resolved bundle
assert declaring a default gem is a real version pin, because the interpreter's own copy still exists and the Gemfile decides which one runs
assert Set resolves through the bundle by autoload, with no require anywhere
assert an OpenStruct key overwrites the method it collides with, so class returns the data, method stops taking an argument, and only [] and to_h read safely
assert OpenStruct overwrites __send__ too, warning that this may cause serious problems, and then refuses an argument
assert a missing OpenStruct key reads as nil through both accessors while to_h.fetch raises KeyError
assert Set dedupes by eql? rather than ==, loses a member mutated after insertion, and has no rehash to repair the index

ruby 3 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · gem@1 · 2026-08-14 · ed25519:a2ec939a4c60e243