Merge pull request #839 from Shopify/uk-fix-generic-type-variable-arg

Fix generic type variable argument serialization

lib/tapioca/runtime/generic_type_registry.rb

@@ -111,8 +111,10 @@ def create_generic_type(constant, name)
             constant.clone
           end
 
-          # Let's set the `name` method to return the proper generic name
-          generic_type.define_singleton_method(:name) { name }
+          # Let's set the `name` and `to_s` methods to return the proper generic name
+          name_proc = -> { name }
+          generic_type.define_singleton_method(:name, name_proc)
+          generic_type.define_singleton_method(:to_s, name_proc)
 
           # We need to define a `<=` method on the cloned constant, so that Sorbet
           # can do covariance/contravariance checks on the type variables.

spec/tapioca/gem/pipeline_spec.rb

@@ -2819,6 +2819,44 @@ class Foo
       assert_equal(output, compile)
     end
 
+    it "can compile generics in type variable arguments" do
+      add_ruby_file("service.rb", <<~RUBY)
+        class Result
+          extend T::Generic
+
+          OkType = type_member
+          ErrType = type_member
+        end
+
+        class Service
+          extend T::Generic
+
+          InputType = type_member(upper: Result[Integer, String])
+          ReturnType = type_member(fixed: Result[Integer, String])
+          TempType = type_member(lower: Result[Integer, String])
+        end
+      RUBY
+
+      output = template(<<~RBI)
+        class Result
+          extend T::Generic
+
+          OkType = type_member
+          ErrType = type_member
+        end
+
+        class Service
+          extend T::Generic
+
+          InputType = type_member(upper: Result[::Integer, ::String])
+          ReturnType = type_member(fixed: Result[::Integer, ::String])
+          TempType = type_member(lower: Result[::Integer, ::String])
+        end
+      RBI
+
+      assert_equal(output, compile)
+    end
+
     it "can compile typed struct generics" do
       add_ruby_file("tstruct_generic.rb", <<~RUBY)
         class Foo < T::Struct