Fix object spreading, issues 6108, 7242, 5243, 7210, 7253, 6357, 5253, 4682, 6800, 981, 7048 and more

src/typing/flow_js.ml

@@ -4870,14 +4870,16 @@ let rec __flow cx ((l: Type.t), (u: Type.use_t)) trace =
           |> replace_reason (fun desc -> RPropertyOf (x, desc))
           |> repos_reason (aloc_of_reason reason_op)
         in
-        match Property.read_t p with
-        | Some t ->
-          let propref = Named (reason_prop, x) in
-          let t = filter_optional cx ~trace reason_prop t in
-          rec_flow cx trace (to_obj, SetPropT (
-            unknown_use, reason_prop, propref, Normal, t, None
-          ))
-        | None ->
+        match Property.read_t p, to_obj with
+        | Some _, (DefT (_, ObjT ob)) when not ob.flags.frozen ->
+          Context.set_prop cx ob.props_tmap x p
+        | Some t, to_obj ->
+            let propref = Named (reason_prop, x) in
+            let t = filter_optional cx ~trace reason_prop t in
+            rec_flow cx trace (to_obj, SetPropT (
+              unknown_use, reason_prop, propref, Normal, t, None
+            ))
+        | None, _ ->
           add_output cx ~trace (FlowError.EPropAccess (
             (reason_prop, reason_op), Some x, Property.polarity p, Read, unknown_use
           ))

tests/friendly_errors/issue_7210.js

@@ -0,0 +1,3 @@
+// @flow
+type Foo = {| +foo: ?string |};
+const test = (bar: Foo): Foo => ({ foo: 'foo', ...bar});

tests/friendly_errors/issue_7242.js

@@ -0,0 +1,9 @@
+// @flow
+
+type Ob = {|+foo: {| +bar: string |}|};
+declare var update: Ob;
+({ foo: { bar: 'valid' }, ...update }: Ob); // Ok
+
+type NestedOb = {|+foo: {| +bar: {| +foo: number |} |}|};
+declare var update2: NestedOb;
+({ foo: { bar: { foo: 123 } }, ...update2 }: NestedOb); // Ok

tests/inexact-object-spread/inexact-object-spread.exp

@@ -0,0 +1 @@
+Found 0 errors

tests/inexact-object-spread/issue_6751.js

@@ -0,0 +1,15 @@
+/* @flow */
+
+type A = { foo: ?string };
+
+function foo(a: A) {
+}
+
+const a: A = { foo: 'foo' };
+const b = { foo: 'foo' };
+
+foo({ ...a, foo: 'foo' }); // OK
+foo({ foo: 'foo', ...a }); // OK
+
+foo({ ...b, foo: 'foo' }); // OK
+foo({ foo: 'foo', ...b }); // OK