[flow][numeric-keys] Better support numeric keys in some contextual t…

…yping scenarios

Summary:
Better support numeric keys in some contextual typing scenarios.

Changelog: [internal]

Reviewed By: SamChou19815

Differential Revision: D66911504

fbshipit-source-id: 98db0f413746ba441843602d2f724321d21788c9

src/analysis/env_builder/eq_test.ml

@@ -147,6 +147,20 @@ module Make
           ) ->
           literal_check_of_expr value
           |> Base.Option.value_map ~default:acc ~f:(fun check -> SMap.add name check acc)
+        | ( _,
+            Init
+              {
+                key =
+                  Ast.Expression.Object.Property.NumberLiteral
+                    (_, { Ast.NumberLiteral.value = key_value; _ });
+                value;
+                shorthand = _;
+              }
+          )
+          when Js_number.is_float_safe_integer key_value ->
+          let name = Dtoa.ecma_string_of_float key_value in
+          literal_check_of_expr value
+          |> Base.Option.value_map ~default:acc ~f:(fun check -> SMap.add name check acc)
         | _ -> acc)
       | Ast.Expression.Object.SpreadProperty _ -> acc
     )

tests/contextual_typing/sentinel_refinements.js

@@ -64,3 +64,9 @@ function function_statics() {
     ...
   } = x => {}; // okay `x` inferred as `mixed`
 }
+
+// Numeric literal key names
+type B = {0: 'a', f: (string) => string} | {0: 'b', f: number => number};
+{
+  const b: B = {f: (v) => (v as string), 0: 'a'}; // OK
+}