Expose queries to the variance map

Summary:
The plumming efforts are not yet done. We need to expose queries, such as get_class_summary to the variable map.

After this, we are able to work on the attached unit test as a starting point.

Note:  I was not sure how to expose the variable_map in the typeOrderTest, so I copied the implementation. This is not ideal, but variable_map requires globalResolution. It's unclear how we can get that in this test. Happy to get any suggestions on this point!

Reviewed By: stroxler

Differential Revision: D63615975

fbshipit-source-id: 779f56b3572828c023cfa278c2000915c5b48aaa

source/analysis/attributeResolution.ml

@@ -779,40 +779,6 @@ let callable_call_special_cases
   | _ -> None
 
 
-(* Creates a function from generic type parameters for a given class to post variance inference *)
-let infer_variance_for_one_param ~generic_type_param =
-  let from_pre_to_post variance =
-    match variance with
-    | Type.Record.PreInferenceVariance.P_Covariant -> Type.Record.Variance.Covariant
-    | Type.Record.PreInferenceVariance.P_Contravariant -> Type.Record.Variance.Contravariant
-    | Type.Record.PreInferenceVariance.P_Invariant -> Type.Record.Variance.Invariant
-    | Type.Record.PreInferenceVariance.P_Undefined -> Type.Record.Variance.Invariant
-  in
-
-  let find_variance =
-    match generic_type_param with
-    | Type.GenericParameter.GpTypeVar { variance; _ } -> from_pre_to_post variance
-    | _ -> Invariant
-  in
-  find_variance
-
-
-let infer_variance_for_all_params parameters =
-  let add_to_lookup so_far = function
-    | Type.GenericParameter.GpTypeVar { name; _ } as gp ->
-        let variance = infer_variance_for_one_param ~generic_type_param:gp in
-        Map.set so_far ~key:name ~data:variance
-    | _ -> so_far
-  in
-  List.fold parameters ~f:add_to_lookup ~init:Identifier.Map.empty
-
-
-(* We will expose this interface as the variance map *)
-let variance_map ~class_name ~parameters =
-  let _class_name = class_name in
-  infer_variance_for_all_params parameters
-
-
 class base ~queries:(Queries.{ controls; _ } as queries) =
   object (self)
     (* Given a `Type.t`, recursively search for parameteric forms with invalid
@@ -2910,6 +2876,40 @@ class base ~queries:(Queries.{ controls; _ } as queries) =
               fields >>| fun fields -> { Type.TypedDictionary.fields; name = class_name })
       | _ -> None
 
+    (* We will expose this interface as the variance map *)
+    method variance_map ~class_name ~parameters =
+      (* Creates a function from generic type parameters for a given class to post variance
+         inference *)
+      let infer_variance_for_one_param ~generic_type_param =
+        let from_pre_to_post variance =
+          match variance with
+          | Type.Record.PreInferenceVariance.P_Covariant -> Type.Record.Variance.Covariant
+          | Type.Record.PreInferenceVariance.P_Contravariant -> Type.Record.Variance.Contravariant
+          | Type.Record.PreInferenceVariance.P_Invariant -> Type.Record.Variance.Invariant
+          | Type.Record.PreInferenceVariance.P_Undefined -> Type.Record.Variance.Invariant
+        in
+
+        let find_variance =
+          match generic_type_param with
+          | Type.GenericParameter.GpTypeVar { variance; _ } -> from_pre_to_post variance
+          | _ -> Invariant
+        in
+        find_variance
+      in
+
+      let infer_variance_for_all_params parameters =
+        let add_to_lookup so_far = function
+          | Type.GenericParameter.GpTypeVar { name; _ } as gp ->
+              let variance = infer_variance_for_one_param ~generic_type_param:gp in
+              Map.set so_far ~key:name ~data:variance
+          | _ -> so_far
+        in
+        List.fold parameters ~f:add_to_lookup ~init:Identifier.Map.empty
+      in
+
+      let _class_name = class_name in
+      infer_variance_for_all_params parameters
+
     (* Construct a ConstraintsSet.order representing the lattice of types for a
      * project. The order object is just a record of callbacks providing access to
      * shared memory for all cases where type order and constraint solving operations
@@ -3026,7 +3026,7 @@ class base ~queries:(Queries.{ controls; _ } as queries) =
         get_typed_dictionary = self#get_typed_dictionary ~cycle_detections;
         get_named_tuple_fields;
         metaclass;
-        variance_map;
+        variance_map = self#variance_map;
       }
 
     (* Given an expression, produce a Type.t where literal type information - that is,
@@ -4191,6 +4191,18 @@ module ReadOnly = struct
     |> fun method_ -> method_ ~cycle_detections:empty_cycle_detections
 
 
+  let variance_map read_only =
+    let queries =
+      create_queries
+        ~dependency:None
+        ~class_metadata_environment:(class_metadata_environment read_only)
+    in
+
+    let implementation = new base ~queries in
+
+    implementation#variance_map
+
+
   let instantiate_attribute =
     add_all_caches_and_empty_cycle_detections (fun o ->
         o#instantiate_attribute ?apply_descriptors:None)

source/analysis/attributeResolution.mli

@@ -157,6 +157,12 @@ module AttributeReadOnly : sig
     right:Type.t ->
     bool
 
+  val variance_map
+    :  t ->
+    class_name:string ->
+    parameters:Type.GenericParameter.t list ->
+    Type.Record.Variance.t Identifier.Map.t
+
   val global : t -> ?dependency:DependencyKey.registered -> Reference.t -> Global.t option
 
   module Testing : sig
@@ -170,11 +176,6 @@ module AttributeReadOnly : sig
   end
 end
 
-val variance_map
-  :  class_name:'a ->
-  parameters:Type.GenericParameter.t list ->
-  Type.Record.Variance.t Identifier.Map.t
-
 include
   Environment.S
     with module ReadOnly = AttributeReadOnly

source/analysis/globalResolution.ml

@@ -255,6 +255,10 @@ let constraints_solution_exists ({ dependency; _ } as resolution) =
     (attribute_resolution resolution)
 
 
+let variance_map resolution =
+  AttributeResolution.ReadOnly.variance_map (attribute_resolution resolution)
+
+
 let uninstantiated_attributes
     ({ dependency; _ } as resolution)
     ?(transitive = false)
@@ -362,7 +366,8 @@ let is_invariance_mismatch resolution ~left ~right =
                   | Type.GenericParameter.GpTypeVar { name; _ } ->
                       let variance =
                         Map.find
-                          (AttributeResolution.variance_map
+                          (variance_map
+                             resolution
                              ~parameters:generic_parameters
                              ~class_name:left_name)
                           name

source/analysis/globalResolution.mli

@@ -105,6 +105,12 @@ val constraints_solution_exists
   right:Type.t ->
   bool
 
+val variance_map
+  :  t ->
+  class_name:string ->
+  parameters:Type.GenericParameter.t list ->
+  Type.Record.Variance.t Identifier.Map.t
+
 val uninstantiated_attributes
   :  t ->
   ?transitive:bool ->

source/analysis/test/constraintsSetTest.ml

@@ -236,7 +236,7 @@ let make_assert_functions context =
           get_typed_dictionary;
           get_named_tuple_fields;
           metaclass;
-          variance_map = AttributeResolution.variance_map;
+          variance_map = GlobalResolution.variance_map (GlobalResolution.create environment);
         }
       in
       let attributes annotation ~cycle_detections =
@@ -1555,7 +1555,7 @@ let test_instantiate_protocol_parameters context =
         get_typed_dictionary;
         get_named_tuple_fields;
         metaclass = (fun _ ~cycle_detections:_ -> Some (Type.Primitive "type"));
-        variance_map = AttributeResolution.variance_map;
+        variance_map = GlobalResolution.variance_map (GlobalResolution.create environment);
       }
     in
     assert_equal
@@ -1730,7 +1730,7 @@ let test_mark_escaped_as_escaped context =
         get_typed_dictionary;
         get_named_tuple_fields;
         metaclass = (fun _ ~cycle_detections:_ -> Some (Type.Primitive "type"));
-        variance_map = AttributeResolution.variance_map;
+        variance_map = GlobalResolution.variance_map (GlobalResolution.create environment);
       }
     in
     TypeOrder.OrderedConstraintsSet.add_and_simplify

source/analysis/test/integration/typeVariableTest.ml

@@ -189,6 +189,28 @@ let test_type_variable_scoping =
              x2: str = foo.f("foo")
            |}
            [];
+      (* The errors about __len__ happen in legacy syntax too. Those errors need further
+         investigation. *)
+      labeled_test_case __FUNCTION__ __LINE__
+      @@ assert_type_errors
+           {|
+            from typing import Sequence
+            class ShouldBeCovariant2[T](Sequence[T]):
+                pass
+
+            vco2_1: ShouldBeCovariant2[float] = ShouldBeCovariant2[int]()  # OK
+            vco2_2: ShouldBeCovariant2[int] = ShouldBeCovariant2[float]()  # E
+            |}
+           [
+             "Incompatible variable type [9]: vco2_1 is declared to have type \
+              `ShouldBeCovariant2[float]` but is used as type `ShouldBeCovariant2[int]`.";
+             "Invalid class instantiation [45]: Cannot instantiate abstract class \
+              `ShouldBeCovariant2` with abstract method `__len__`.";
+             "Incompatible variable type [9]: vco2_2 is declared to have type \
+              `ShouldBeCovariant2[int]` but is used as type `ShouldBeCovariant2[float]`.";
+             "Invalid class instantiation [45]: Cannot instantiate abstract class \
+              `ShouldBeCovariant2` with abstract method `__len__`.";
+           ];
     ]
 
 

source/analysis/test/typeOrderTest.ml

@@ -141,6 +141,41 @@ let attribute_from_attributes attributes =
   attribute
 
 
+(* TODO migeedz: duplicate implementation since I need global resolution to be able to invoke the
+   variable map. Is there a way to obtain it here? we need the source and the test context. *)
+let variance_map ~class_name ~parameters =
+  (* Creates a function from generic type parameters for a given class to post variance inference *)
+  let infer_variance_for_one_param ~generic_type_param =
+    let from_pre_to_post variance =
+      match variance with
+      | Type.Record.PreInferenceVariance.P_Covariant -> Type.Record.Variance.Covariant
+      | Type.Record.PreInferenceVariance.P_Contravariant -> Type.Record.Variance.Contravariant
+      | Type.Record.PreInferenceVariance.P_Invariant -> Type.Record.Variance.Invariant
+      | Type.Record.PreInferenceVariance.P_Undefined -> Type.Record.Variance.Invariant
+    in
+
+    let find_variance =
+      match generic_type_param with
+      | Type.GenericParameter.GpTypeVar { variance; _ } -> from_pre_to_post variance
+      | _ -> Invariant
+    in
+    find_variance
+  in
+
+  let infer_variance_for_all_params parameters =
+    let add_to_lookup so_far = function
+      | Type.GenericParameter.GpTypeVar { name; _ } as gp ->
+          let variance = infer_variance_for_one_param ~generic_type_param:gp in
+          Map.set so_far ~key:name ~data:variance
+      | _ -> so_far
+    in
+    List.fold parameters ~f:add_to_lookup ~init:Identifier.Map.empty
+  in
+
+  let _class_name = class_name in
+  infer_variance_for_all_params parameters
+
+
 let less_or_equal
     ?(attributes = fun _ ~cycle_detections:_ -> None)
     ?(is_protocol = fun _ -> false)
@@ -161,7 +196,7 @@ let less_or_equal
       get_typed_dictionary;
       get_named_tuple_fields;
       metaclass = (fun _ ~cycle_detections:_ -> Some (Type.Primitive "type"));
-      variance_map = AttributeResolution.variance_map;
+      variance_map;
     }
 
 
@@ -181,7 +216,7 @@ let join ?(attributes = fun _ ~cycle_detections:_ -> None) handler =
       get_typed_dictionary;
       get_named_tuple_fields;
       metaclass = (fun _ ~cycle_detections:_ -> Some (Type.Primitive "type"));
-      variance_map = AttributeResolution.variance_map;
+      variance_map;
     }
 
 
@@ -201,7 +236,7 @@ let meet handler =
       get_typed_dictionary;
       get_named_tuple_fields;
       metaclass = (fun _ ~cycle_detections:_ -> Some (Type.Primitive "type"));
-      variance_map = AttributeResolution.variance_map;
+      variance_map;
     }
 
 

source/analysis/typeCheck.ml

@@ -6240,7 +6240,8 @@ module State (Context : Context) = struct
                 |> Option.value ~default:[]
               in
               let look_up_this_class_variance =
-                AttributeResolution.variance_map
+                GlobalResolution.variance_map
+                  global_resolution
                   ~parameters:generic_parameters
                   ~class_name:this_class_name
               in
@@ -6258,7 +6259,10 @@ module State (Context : Context) = struct
                   Type.GenericParameter.GpTypeVar { name = base_name; _ } ) -> (
                   let base_variance =
                     Map.find
-                      (AttributeResolution.variance_map ~parameters ~class_name:base_class_name)
+                      (GlobalResolution.variance_map
+                         global_resolution
+                         ~parameters
+                         ~class_name:base_class_name)
                       base_name
                     |> Option.value ~default:Type.Record.Variance.Invariant
                   in
@@ -6566,7 +6570,8 @@ module State (Context : Context) = struct
             GlobalResolution.generic_parameters global_resolution current_class_name
             |> Option.value ~default:[]
           in
-          AttributeResolution.variance_map
+          GlobalResolution.variance_map
+            global_resolution
             ~parameters:generic_parameters
             ~class_name:current_class_name
       | None -> Identifier.Map.empty