Reimplement RBS/Style/InstanceWithInstance

- Module is not target since it has a different meaning from `instance` and `self`.
- Interface has `interface` as invalid.
- The meaning of `self` and `instance` changes in generic class.

lib/rubocop/cop/rbs/style/instance_with_instance.rb

@@ -18,20 +18,24 @@ class InstanceWithInstance < RuboCop::RBS::CopBase
           extend AutoCorrector
           MSG = 'Use `self` instead of `instance`.'
 
-          def on_rbs_def(decl)
-            return unless decl.kind == :instance
+          # @rbs decl: RBS::AST::Declarations::Class
+          def on_rbs_class(decl)
+            # The meaning of `self` and `instance` changes in generic class.
+            return unless decl.type_params.empty?
 
-            decl.overloads.each do |overload|
-              overload.method_type.each_type do |type|
-                check_type(type)
-              end
-            end
-          end
+            decl.members.each do |member|
+              case member
+              when ::RBS::AST::Members::MethodDefinition
+                next unless member.kind == :instance
 
-          def on_rbs_var(decl)
-            case decl
-            when ::RBS::AST::Members::InstanceVariable
-              check_type(decl.type)
+                member.overloads.each do |overload|
+                  overload.method_type.each_type do |type|
+                    check_type(type)
+                  end
+                end
+              when ::RBS::AST::Members::InstanceVariable
+                check_type(member.type)
+              end
             end
           end
 

sig/generated/rubocop/cop/rbs/style/instance_with_instance.rbs

@@ -17,9 +17,8 @@ module RuboCop
 
           MSG: ::String
 
-          def on_rbs_def: (untyped decl) -> untyped
-
-          def on_rbs_var: (untyped decl) -> untyped
+          # @rbs decl: RBS::AST::Declarations::Class
+          def on_rbs_class: (RBS::AST::Declarations::Class decl) -> untyped
 
           def check_type: (untyped type) -> untyped
         end

spec/rubocop/cop/rbs/style/instance_with_instance_spec.rb

@@ -6,8 +6,12 @@
   it 'registers an offense' do
     expect_offense(<<~RBS)
       class Foo
-        def foo: () -> instance
-                       ^^^^^^^^ Use `self` instead of `instance`.
+        def foo: (instance) -> instance
+                  ^^^^^^^^ Use `self` instead of `instance`.
+                               ^^^^^^^^ Use `self` instead of `instance`.
+
+        def bar: [T] () { () [self: instance] -> void } -> T
+                                    ^^^^^^^^ Use `self` instead of `instance`.
 
         def self.foo: () -> instance
 
@@ -24,7 +28,9 @@ def self?.foo: () -> instance
 
     expect_correction(<<~RBS)
       class Foo
-        def foo: () -> self
+        def foo: (self) -> self
+
+        def bar: [T] () { () [self: self] -> void } -> T
 
         def self.foo: () -> instance
 
@@ -38,4 +44,48 @@ def self?.foo: () -> instance
       end
     RBS
   end
+
+  it 'registers an offense on inherited generic class' do
+    expect_offense(<<~RBS)
+      class Bar < Foo[Integer]
+        def foo: (instance) -> instance
+                  ^^^^^^^^ Use `self` instead of `instance`.
+                               ^^^^^^^^ Use `self` instead of `instance`.
+      end
+    RBS
+
+    expect_correction(<<~RBS)
+      class Bar < Foo[Integer]
+        def foo: (self) -> self
+      end
+    RBS
+  end
+
+  it 'does not register an offense' do
+    expect_no_offenses(<<~RBS)
+      class Generic[T]
+        def a: () -> instance
+      end
+    RBS
+
+    expect_no_offenses(<<~RBS)
+      module Foo
+        def foo: () -> instance
+
+        @ivar: instance
+      end
+
+      class Bar
+        module Foo
+          def foo: () -> instance
+        end
+      end
+    RBS
+
+    expect_no_offenses(<<~RBS)
+      interface _Foo
+        def foo: () -> instance
+      end
+    RBS
+  end
 end