improve member expression reasons

Summary:
for member expressions, we have separate `prop_reason` and `expr_reason`, but were using the same `RProperty` for both in some cases, which renders like `property "foo"`. instead, switched to using `mk_expression_reason` for `expr_reason`.

then had to introduce `RMember` to preserve the "constant" hack we get from `RProperty` where all-uppercase props are treated like constants.

Reviewed By: panagosg7

Differential Revision: D15317704

fbshipit-source-id: 06a1d934d254f390319dc5c396f84ac9521c6c8c

src/common/reason.ml

@@ -151,6 +151,7 @@ type 'loc virtual_reason_desc =
   | RProperty of string option
   | RPrivateProperty of string
   | RShadowProperty of string
+  | RMember of { object_: string; property: string }
   | RPropertyOf of string * 'loc virtual_reason_desc
   | RPropertyIsAString of string
   | RMissingProperty of string option
@@ -303,6 +304,7 @@ let rec map_desc_locs f = function
   | RProperty _
   | RPrivateProperty _
   | RShadowProperty _
+  | RMember _
   | RPropertyIsAString _
   | RMissingProperty _
   | RUnknownProperty _
@@ -669,6 +671,7 @@ let rec string_of_desc = function
   | RProperty (Some x) -> spf "property `%s`" x
   | RProperty None -> "computed property"
   | RPrivateProperty x -> spf "property `#%s`" x
+  | RMember { object_; property } -> spf "`%s%s`" object_ property
   | RPropertyAssignment (Some x) -> spf "assignment of property `%s`" x
   | RPropertyAssignment None -> "assignment of computed property/element"
   | RShadowProperty x -> spf ".%s" x
@@ -839,6 +842,7 @@ let is_constant_reason r =
   | RIdentifier x
   | RProperty (Some x)
   | RPrivateProperty x
+  | RMember { object_ = _; property = x }
   | RPropertyOf (x,_)
   | RPropertyIsAString x ->
     let len = String.length x in
@@ -1012,13 +1016,10 @@ Ast.Expression.(match x with
 | Ast.Expression.Literal x -> code_desc_of_literal x
 | Logical { Logical.operator; left; right } ->
   do_wrap (code_desc_of_operation left (`Logical operator) right)
-| Member { Member._object; property } -> Member.(
+| Member { Member._object; property } ->
   let o = code_desc_of_expression ~wrap:true _object in
-  o ^ (match property with
-  | PropertyIdentifier (_, { Ast.Identifier.name= x; comments= _ }) -> "." ^ x
-  | PropertyPrivateName (_, (_, { Ast.Identifier.name= x; comments= _ })) -> ".#" ^ x
-  | PropertyExpression x -> "[" ^ code_desc_of_expression ~wrap:false x ^ "]"
-  ))
+  let p = code_desc_of_property ~optional:false property in
+  o ^ p
 | MetaProperty { MetaProperty.meta = (_, { Ast.Identifier.name= o; comments= _ }); property = (_, { Ast.Identifier.name= p; comments= _ }) } ->
   o ^ "." ^ p
 | New { New.callee; targs; arguments } ->
@@ -1054,12 +1055,8 @@ Ast.Expression.(match x with
     optional;
   } ->
   let o = code_desc_of_expression ~wrap:true _object in
-  o ^ Member.(match property with
-  | PropertyIdentifier (_, { Ast.Identifier.name= x; comments= _ }) -> (if optional then "?." else ".") ^ x
-  | PropertyPrivateName (_, (_, { Ast.Identifier.name= x; comments= _ })) -> (if optional then "?.#" else ".#") ^ x
-  | PropertyExpression x ->
-    (if optional then "?.[" else "[") ^ code_desc_of_expression ~wrap:false x ^ "]"
-  )
+  let p = code_desc_of_property ~optional property in
+  o ^ p
 | Sequence { Sequence.expressions } ->
   code_desc_of_expression ~wrap (List.hd (List.rev expressions))
 | Super -> "super"
@@ -1192,6 +1189,16 @@ and code_desc_of_literal x = Ast.(match x.Literal.value with
 | _ -> x.Literal.raw
 )
 
+and code_desc_of_property ~optional property =
+  match property with
+  | Ast.Expression.Member.PropertyIdentifier (_, { Ast.Identifier.name= x; comments= _ }) ->
+      (if optional then "?." else ".") ^ x
+  | Ast.Expression.Member.PropertyPrivateName (_, (_, { Ast.Identifier.name= x; comments= _ })) ->
+      (if optional then "?.#" else ".#") ^ x
+  | Ast.Expression.Member.PropertyExpression x ->
+      (if optional then "?.[" else "[") ^ code_desc_of_expression ~wrap:false x ^ "]"
+
+
 let rec mk_expression_reason = Ast.Expression.(function
 | (loc, TypeCast { TypeCast.expression; _ }) -> repos_reason loc (mk_expression_reason expression)
 | (loc, Object _) -> mk_reason RObjectLit loc
@@ -1202,6 +1209,11 @@ let rec mk_expression_reason = Ast.Expression.(function
   mk_reason (RStringLit "") loc
 | (loc, TaggedTemplate _) -> mk_reason RTemplateString loc
 | (loc, TemplateLiteral _) -> mk_reason RTemplateString loc
+| (loc, Member { Member._object; property }) ->
+  mk_reason (RMember {
+    object_ = code_desc_of_expression ~wrap:true _object;
+    property = code_desc_of_property ~optional:false property;
+  }) loc
 | (loc, _) as x -> mk_reason (RCode (code_desc_of_expression ~wrap:false x)) loc
 )
 
@@ -1332,6 +1344,7 @@ let classification_of_reason r = match desc_of_reason ~unwrap:true r with
 | RProperty _
 | RPrivateProperty _
 | RShadowProperty _
+| RMember _
 | RPropertyOf _
 | RPropertyIsAString _
 | RMissingProperty _

src/common/reason.mli

@@ -98,6 +98,7 @@ type 'loc virtual_reason_desc =
   | RProperty of string option
   | RPrivateProperty of string
   | RShadowProperty of string
+  | RMember of { object_: string; property: string }
   | RPropertyOf of string * 'loc virtual_reason_desc
   | RPropertyIsAString of string
   | RMissingProperty of string option

src/typing/statement.ml

@@ -4245,9 +4245,9 @@ and subscript =
         Member._object;
         property = Member.PropertyIdentifier (ploc, ({ Ast.Identifier.name; comments= _ } as id));
       } ->
-        let expr_reason = mk_reason (RProperty (Some name)) loc in
+        let expr_reason = mk_expression_reason ex in
         let prop_reason = mk_reason (RProperty (Some name)) ploc in
-        let use_op = Op (GetProperty (mk_expression_reason ex)) in
+        let use_op = Op (GetProperty expr_reason) in
         begin match opt_state with
         | NonOptional ->
           let (_, tobj), _ as _object_ast = expression cx _object in
@@ -5635,7 +5635,7 @@ and predicates_of_condition cx e = Ast.(Expression.(
       let (_, obj_t), _ as _object_ast = expression cx _object in
 
       let prop_reason = mk_reason (RProperty (Some prop_name)) prop_loc in
-      let expr_reason = mk_reason (RProperty (Some prop_name)) expr_loc in
+      let expr_reason = mk_expression_reason expr in
       let prop_t = match Refinement.get cx expr expr_loc with
       | Some t -> t
       | None ->
@@ -5988,7 +5988,7 @@ and predicates_of_condition cx e = Ast.(Expression.(
              as `_object = foo.bar`, `prop_name = baz`, and `bar` must exist. *)
           expression cx _object
       in
-      let expr_reason = mk_reason (RProperty (Some prop_name)) loc in
+      let expr_reason = mk_expression_reason e in
       let prop_reason = mk_reason (RProperty (Some prop_name)) prop_loc in
       let t = match Refinement.get cx e loc with
       | Some t -> t

tests/new_react/new_react.exp

@@ -1,6 +1,6 @@
 Error --------------------------------------------------------------------------------------- bad_default_props.js:15:18
 
-Cannot use property `Component` [1] with fewer than 1 type argument.
+Cannot use `React.Component` [1] with fewer than 1 type argument.
 
    bad_default_props.js:15:18
    15| class C3 extends React.Component { // error
@@ -14,7 +14,7 @@ References:
 
 Error --------------------------------------------------------------------------------------- bad_default_props.js:20:18
 
-Cannot use property `Component` [1] with fewer than 1 type argument.
+Cannot use `React.Component` [1] with fewer than 1 type argument.
 
    bad_default_props.js:20:18
    20| class C4 extends React.Component {
@@ -28,7 +28,7 @@ References:
 
 Error --------------------------------------------------------------------------------------------------- classes.js:7:1
 
-Cannot extend property `Component` [1] with `Foo` because:
+Cannot extend `React.Component` [1] with `Foo` because:
  - property `y_` is missing in function type [2] but exists in object type [3] in the first argument of property
    `setState`.
  - property `y_` is missing in `State` [4] but exists in object type [3] in the first argument of property `setState`.

tests/react/react.exp

@@ -2775,7 +2775,7 @@ References:
 
 Error ---------------------------------------------------------------------------------------------------- render.js:8:1
 
-Cannot extend property `Component` [1] with `A` because in the return value of property `render`:
+Cannot extend `React.Component` [1] with `A` because in the return value of property `render`:
  - Either undefined [2] is incompatible with null [3].
  - Or property `@@iterator` is missing in undefined [2] but exists in `$Iterable` [4].
 
@@ -2850,7 +2850,7 @@ References:
 
 Error --------------------------------------------------------------------------------------------------- render.js:46:1
 
-Cannot extend property `Component` [1] with `F` because in the return value of property `render`:
+Cannot extend `React.Component` [1] with `F` because in the return value of property `render`:
  - Either undefined [2] is incompatible with null [3].
  - Or property `@@iterator` is missing in undefined [2] but exists in `$Iterable` [4].