From 44c8664da064741e9ab7e7d934752e15c4bcd725 Mon Sep 17 00:00:00 2001
From: Ufuk Kayserilioglu <ufuk@paralaus.com>
Date: Tue, 1 Mar 2022 21:08:25 +0200
Subject: [PATCH 1/2] Add failing test

---
 spec/tapioca/gem/pipeline_spec.rb | 38 +++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/spec/tapioca/gem/pipeline_spec.rb b/spec/tapioca/gem/pipeline_spec.rb
index af0cc38e0..e41e3617c 100644
--- a/spec/tapioca/gem/pipeline_spec.rb
+++ b/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

From 4e648253a9c06e0986cc0e810442848517b03ed8 Mon Sep 17 00:00:00 2001
From: Ufuk Kayserilioglu <ufuk@paralaus.com>
Date: Tue, 1 Mar 2022 21:15:45 +0200
Subject: [PATCH 2/2] Override `to_s` on generic clones as well

---
 lib/tapioca/runtime/generic_type_registry.rb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/tapioca/runtime/generic_type_registry.rb b/lib/tapioca/runtime/generic_type_registry.rb
index 1bc1c6a8a..98828a597 100644
--- a/lib/tapioca/runtime/generic_type_registry.rb
+++ b/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.