Merge branch 'master' into awaitedType2

src/compiler/checker.ts

@@ -30024,18 +30024,20 @@ namespace ts {
 
         /**
          * Determines whether a type is a generic type whose base constraint could possibly resolve to a different
-         * type when awaited. A type is a generic "thenable" type when the type is a generic object type and
-         * any of the following conditions are met
-         * - The type has no base constraint.
-         * - OR The base constraint of the type is `any` or `unknown` or the empty object `{}`.
-         * - OR The base constraint has a callable `then` member.
+         * type when awaited. A type is a generic "thenable" type when all of the following conditions are met:
+         * - The type is a generic object type,
+         * - AND one of the following conditions are met
+         *   - The type has no base constraint,
+         *   - OR The base constraint of the type is `any`, `unknown`, `object`, or the empty object `{}`,
+         *   - OR The base constraint has a callable `then` member.
          */
         function isGenericAwaitableType(type: Type): boolean {
             if (isGenericObjectType(type)) {
                 const baseConstraint = getBaseConstraintOfType(type);
                 return !baseConstraint ||
-                    !!(baseConstraint.flags & (TypeFlags.AnyOrUnknown)) ||
+                    !!(baseConstraint.flags & (TypeFlags.AnyOrUnknown | TypeFlags.NonPrimitive)) ||
                     baseConstraint === emptyObjectType ||
+                    baseConstraint === emptyGenericType ||
                     isThenableType(baseConstraint);
             }
             return false;