These signatures seem to be incorrect:
RubyVM::AbstractSyntaxTree::YJIT
- should be RubyVM::YJIT
instead (see yjit.rb).
RubyVM::AbstractSyntaxTree::RJIT
- should be RubyVM::RJIT
instead (see rjit.rb).
Gem::UNTAINT
- got removed together with other 2.7 staff (see 545113).