[react] reserve React$AbstractComponent

Summary:
Adds React$AbstractComponent as a built-in that expects 3 type arguments. I'll be building out the functionality of this type in stacked diffs.

OSS Users: I will follow up with a blog post when we get closer to having this type actually be usable. We expect it to improve the precision and speed with which flow can typecheck React components.

Reviewed By: samwgoldman

Differential Revision: D12925858

fbshipit-source-id: e242dbf74ed2b90eca3fb7f66641bee8b919e530

src/typing/debug_js.ml

@@ -2813,3 +2813,5 @@ let dump_flow_error =
       spf "EUnexpectedTemporaryBaseType (%s)" (string_of_aloc loc)
     | ESignatureVerification sve ->
       spf "ESignatureVerification (%s)" (Signature_builder_deps.With_ALoc.Error.debug_to_string sve)
+    | EAbstractComponentNotYetSupported loc ->
+      spf "EAbstractComponentNotYetSupported (%s)" (string_of_aloc loc)

src/typing/flow_error.ml

@@ -171,6 +171,7 @@ type error_message =
   | EDeprecatedCallSyntax of ALoc.t
   | EUnexpectedTemporaryBaseType of ALoc.t
   | ESignatureVerification of Signature_builder_deps.With_ALoc.Error.t
+  | EAbstractComponentNotYetSupported of ALoc.t
 
 and binding_error =
   | ENameAlreadyBound
@@ -399,6 +400,7 @@ let util_use_op_of_msg nope util = function
 | EDeprecatedCallSyntax _
 | EUnexpectedTemporaryBaseType _
 | ESignatureVerification _
+| EAbstractComponentNotYetSupported _
   -> nope
 
 (* Rank scores for signals of different strength on an x^2 scale so that greater
@@ -1883,6 +1885,9 @@ let rec error_of_msg ~trace_reasons ~source_file =
         ]
     end
 
+  | EAbstractComponentNotYetSupported loc ->
+      mk_error ~trace_infos loc [text "React$AbstractComponent is not supported yet."]
+
   | EUnreachable loc ->
     mk_error ~trace_infos ~kind:InferWarning loc
       [text "Unreachable code."]

src/typing/type_annotation.ml

@@ -584,6 +584,10 @@ let rec convert cx tparams_map = Ast.Type.(function
   | "$ComposeReverse" ->
       mk_custom_fun cx loc targs ident (Compose true)
 
+  | "React$AbstractComponent" ->
+      check_type_arg_arity cx loc targs 3 (fun () ->
+        error_type cx loc (FlowError.EAbstractComponentNotYetSupported loc)
+      )
   | "React$PropType$Primitive" ->
       check_type_arg_arity cx loc targs 1 (fun () ->
         let ts, targs = convert_type_params () in

tests/react_abstract_component/react_abstract_component.exp

@@ -0,0 +1,34 @@
+Error ----------------------------------------------------------------------------------------------------- test.js:3:19
+
+React$AbstractComponent is not supported yet.
+
+   3| function test1(x: React$AbstractComponent<any, any, any>) { // Error not yet supported
+                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+Error ----------------------------------------------------------------------------------------------------- test.js:7:19
+
+Cannot use type without exactly 3 type arguments.
+
+   7| function test2(x: React$AbstractComponent<any>) { // Not enough targs
+                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------------------- test.js:11:19
+
+Cannot use type without exactly 3 type arguments.
+
+   11| function test3(x: React$AbstractComponent<any,any>) { // Not enough targs
+                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+Error ---------------------------------------------------------------------------------------------------- test.js:15:19
+
+Cannot use type without exactly 3 type arguments.
+
+   15| function test4(x: React$AbstractComponent<any,any,any,any>) { // Too many targs
+                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+
+
+Found 4 errors

tests/react_abstract_component/test.js

@@ -0,0 +1,17 @@
+//@flow
+
+function test1(x: React$AbstractComponent<any, any, any>) { // Error not yet supported
+  return x;
+}
+
+function test2(x: React$AbstractComponent<any>) { // Not enough targs
+  return x;
+}
+
+function test3(x: React$AbstractComponent<any,any>) { // Not enough targs
+  return x;
+}
+
+function test4(x: React$AbstractComponent<any,any,any,any>) { // Too many targs
+  return x;
+}