Goto definition/implementation

[soutaro]

I plan to implement two LSP features:

• Goto Definition
• Goto Implementation

Terminology

The terminology is specific to Steep. I don't know if the definition is common to projects other than Steep.

• A declaration is a declaration in RBS files. Declaration cannot be written in Ruby code.
• A implementation is a Ruby code. It may be a class definition, module definition, method definition, constant definition, ...
• A definition is one of a declaration and implementation.

Based on the terminology, the Goto Definition feature would work as follows:

1. When it is on a method call, constant, global, or anything defined in RBS, it navigates to declarations in RBS file.
2. When it is on a declaration in RBS file, it navigates to implementation in Ruby code.
3. When it is on a implementation in Ruby code, it navigatets to declarations in RBS file.

Goto Implementation would navigate to implementation, and it cannot go to declaration.

(We can extend the definition to Goto declaration in a straightforward way.)

Pull requests

• Start implementation 🎉 Go to Definition/Implementation #371
• Goto from new method call doesn't work well Handling goto-definition of .new method #375
• Confirm if it works for ... overloaded method

[soutaro]

Confirmed how it works for ... overloaded methods:

• If the method is defined in the same class, it jumps to both of the def of the method
• If the method is defined in a different class/module, it cannot jump to the original def

class Foo
  def to_s: (Integer) -> void
          | ...             # Overload with Object#to_s
end

The Foo.new.to_s cannot resolve to Object#to_s.

This is not the best behavior, but I think it's reasonable to ship without fixing the problem.