Fix VirtualMetaclassType#implements? to ignore base_type

spec/compiler/codegen/cast_spec.cr

@@ -423,4 +423,16 @@ describe "Code gen: cast" do
       A.as(A.class)
       ))
   end
+
+  it "cast virtual metaclass type to nilable virtual instance type (#12628)" do
+    run(<<-CR).to_b.should be_true
+      abstract struct Base
+      end
+
+      struct Impl < Base
+      end
+
+      Base.as(Base | Base.class).as?(Base | Impl).nil?
+      CR
+  end
 end

spec/compiler/codegen/is_a_spec.cr

@@ -922,4 +922,16 @@ describe "Codegen: is_a?" do
       b.is_a?(B(Int32))
     )).to_b.should be_true
   end
+
+  it "virtual metaclass type is not virtual instance type (#12628)" do
+    run(<<-CR).to_b.should be_false
+      abstract struct Base
+      end
+
+      struct Impl < Base
+      end
+
+      Base.as(Base | Base.class).is_a?(Base | Impl)
+      CR
+  end
 end

spec/compiler/semantic/metaclass_spec.cr

@@ -134,6 +134,18 @@ describe "Semantic: metaclass" do
       bar_class.should be_a_proper_subtype_of(foo_class)
     end
 
+    it "virtual metaclass type with virtual type (#12628)" do
+      mod = semantic(%(
+        class Base; end
+        class Impl < Base; end
+        )).program
+
+      base = mod.types["Base"]
+      base.virtual_type!.metaclass.implements?(base).should be_false
+      base.virtual_type!.metaclass.implements?(base.metaclass).should be_true
+      base.virtual_type!.metaclass.implements?(base.metaclass.virtual_type!).should be_true
+    end
+
     it "generic classes (1)" do
       mod = semantic(%(
         class Foo(T); end

src/compiler/crystal/types.cr

@@ -3513,7 +3513,7 @@ module Crystal
     end
 
     def implements?(other_type)
-      super || base_type.implements?(other_type)
+      base_type.metaclass.implements?(other_type)
     end
 
     def to_s_with_options(io : IO, skip_union_parens : Bool = false, generic_args : Bool = true, codegen : Bool = false) : Nil