Rails 8.1 deprecation warnings for LoadInterlockAwareMonitor during DSL generation

[amilligan]

Description

When running tapioca dsl with Rails 8.1, five deprecation warnings are emitted:

DEPRECATION WARNING: ActiveSupport::Concurrency::LoadInterlockAwareMonitor is deprecated and will be removed in Rails 9.0. Use Monitor directly instead, as the loading interlock is no longer used.

Root Cause

Rails 8.1 deprecated ActiveSupport::Concurrency::LoadInterlockAwareMonitor by replacing it with a DeprecatedConstantProxy. This proxy emits a deprecation warning whenever the constant is accessed - even for inspection.

During DSL RBI generation, Tapioca's compilers iterate over all loaded modules and constants via all_modules.select { ... } in gather_constants methods. When these compilers encounter LoadInterlockAwareMonitor, simply accessing the constant triggers the deprecation warning.

The warnings originate from these compilers:

• Tapioca::Dsl::Compilers::ActiveSupportConcern (lines 73-76)
• Tapioca::Dsl::Compilers::MixedInClassAttributes (line 72-73)
• Tapioca::Dsl::Compilers::UrlHelpers (lines 119-125)

Reproduction Steps

1. Create a Rails 8.1 application with Sorbet/Tapioca
2. Run bin/tapioca dsl
3. Observe the deprecation warnings in output

Expected Behavior

tapioca dsl should run without emitting deprecation warnings for deprecated constant proxies that are merely being enumerated.

Environment

• Tapioca version: 0.17.10
• Rails version: 8.1.1
• Ruby version: 3.4.7

Possible Solutions

1. Filter out DeprecatedConstantProxy constants - In the gather_constants methods, check if a constant is a DeprecatedConstantProxy before accessing it for inspection
2. Silence deprecations during constant enumeration - Wrap the constant enumeration in ActiveSupport.deprecator.silence { ... }

Workaround

As a temporary workaround, projects can add a custom deprecation behavior in a Rails initializer:

original_behaviors = ActiveSupport.deprecator.behavior.dup
ActiveSupport.deprecator.behavior = -> (message, callstack, deprecator) do
  return if message.to_s.include?("LoadInterlockAwareMonitor")

  original_behaviors.each do |behavior|
    behavior.call(message, callstack, deprecator)
  end
end

Related

• Rails PR that deprecated the class: after_commit callbacks on model with has_many_attached no longer able to detect new attachments rails/rails#53452