Fix "method redefined" warnings introduced in Faraday 2.7.5

[mattbrictson]

Description

Faraday 2.7.5 prints warnings about redefined methods. This was reported in #1505.

faraday-2.7.5/lib/faraday/options.rb:177: warning: method redefined; discarding old user
faraday-2.7.5/lib/faraday/options.rb:177: warning: method redefined; discarding old password
faraday-2.7.5/lib/faraday/options.rb:177: warning: method redefined; discarding old request
faraday-2.7.5/lib/faraday/options.rb:177: warning: method redefined; discarding old ssl
faraday-2.7.5/lib/faraday/options.rb:177: warning: method redefined; discarding old builder_class
faraday-2.7.5/lib/faraday/request.rb:48: warning: method redefined; discarding old params=
faraday-2.7.5/lib/faraday/request.rb:59: warning: method redefined; discarding old headers=
faraday-2.7.5/lib/faraday/request/instrumentation.rb:10: warning: method redefined; discarding old name
faraday-2.7.5/lib/faraday/request/instrumentation.rb:15: warning: method redefined; discarding old instrumenter

The underlying problem is that these methods are implicitly defined by Struct. When Faraday attempts to redefine them to alter the default Struct behavior, the warnings are printed.

Fix by using remove_method to remove the default Struct implementation before Faraday's are declared.

I tested that the warnings are no longer printed on Ruby 2.6 and 2.7 (via Docker) and 3.0, 3.1, and 3.2 (on macOS via rbenv).

Fixes #1505

[mattbrictson]

🗒️ This ensures that Ruby warnings are printed when running the specs.

[mattbrictson]

🗒️ The memoized helper can be used to memoize existing methods, or it can be used to create entirely new methods. So it is necessary to check whether the method exists before attempting to remove it.

The specs have an example of memoized being used to synthesize a previously non-existent method a:

faraday/spec/faraday/options/options_spec.rb

Line 260 in d40f3db

options_class.memoized(:a) { :foo }

[mattbrictson]

🗒️ Since Request is defined via Struct.new, it already has getter and setter methods for its struct attributes, which include params and params=. The code that follows this statement redefines the params= method, which would normally trigger a "method redefined" warning. To avoid that warning, I am explicitly removing the default Struct method first.

I've applied this pattern to the other method definitions that were triggering warnings.

[iMacTia]

Right, that makes sense now!

Before the switch from inheritance (Request < Struct(...)) to assignment (Request = Struct(...)), these methods were defined in the superclass, so these definitions were simply overriding the parent implementation.
Now they're technically redefinition, which triggers the Ruby warning.

Great catch!

[iMacTia]

Thank you for providing the fix AND the insightful comments 🙏
I was a bit at a loss as to how this was introduced, but now I can clearly see why 🎉

[iMacTia]

Right, that makes sense now!

Before the switch from inheritance (Request < Struct(...)) to assignment (Request = Struct(...)), these methods were defined in the superclass, so these definitions were simply overriding the parent implementation.
Now they're technically redefinition, which triggers the Ruby warning.

Great catch!