From 103635f695d8f8df975b387bf9a84df10274cb22 Mon Sep 17 00:00:00 2001
From: Turadg Aleahmad <turadg@agoric.com>
Date: Thu, 23 Jun 2022 07:03:31 -0700
Subject: [PATCH 1/2] fix: typedef of E() proxy parameter constraint

---
 packages/eventual-send/src/index.d.ts      |  4 ++--
 packages/eventual-send/src/index.test-d.ts | 27 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/packages/eventual-send/src/index.d.ts b/packages/eventual-send/src/index.d.ts
index 0b3064e267..997dd9ec91 100644
--- a/packages/eventual-send/src/index.d.ts
+++ b/packages/eventual-send/src/index.d.ts
@@ -234,7 +234,7 @@ interface EProxy {
    * @param x target for method/function call
    * @returns method/function call proxy
    */
-  <T>(x: T): ECallableOrMethods<RemoteFunctions<T>>;
+  <T extends {}>(x: T): ECallableOrMethods<RemoteFunctions<T>>;
 
   /**
    * E.get(x) returns a proxy on which you can get arbitrary properties.
@@ -245,7 +245,7 @@ interface EProxy {
    * @param x target for property get
    * @returns property get proxy
    */
-  readonly get: <T>(x: T) => EGetters<LocalRecord<T>>;
+  readonly get: <T extends {}>(x: T) => EGetters<LocalRecord<T>>;
 
   /**
    * E.resolve(x) converts x to a handled promise. It is
diff --git a/packages/eventual-send/src/index.test-d.ts b/packages/eventual-send/src/index.test-d.ts
index 74aca3b523..a96fed2fe0 100644
--- a/packages/eventual-send/src/index.test-d.ts
+++ b/packages/eventual-send/src/index.test-d.ts
@@ -46,3 +46,30 @@ const foo2 = async (a: FarRef<{ bar(): string; baz: number }>) => {
   // @ts-expect-error - calling directly is valid but not yet in the typedef
   a.bar;
 };
+
+// Nullish handling
+type SomeRemotable = { someMethod: () => 'hello'; someVal: 'alsoHello' };
+const undefinedCase = () => {
+  let ref: SomeRemotable | undefined;
+  // @ts-expect-error could be undefined
+  E(ref).someMethod();
+  // @ts-expect-error optional chaining doesn't work with E()
+  E(ref)?.someMethod();
+  // @ts-expect-error could be undefined
+  E.get(ref);
+  const getters = E.get(ref!);
+  getters.someMethod.then(sayHello => sayHello());
+  getters.someVal;
+};
+const nullCase = () => {
+  let ref: SomeRemotable | null;
+  // @ts-expect-error could be null
+  E(ref).someMethod();
+  // @ts-expect-error optional chaining doesn't work with E()
+  E(ref)?.someMethod();
+  // @ts-expect-error could be null
+  E.get(ref);
+  const getters = E.get(ref!);
+  getters.someMethod.then(sayHello => sayHello());
+  getters.someVal;
+};

From c4f23d754d92883b5f470bc74a0b029e152e0e08 Mon Sep 17 00:00:00 2001
From: Turadg Aleahmad <turadg@agoric.com>
Date: Tue, 28 Jun 2022 09:58:29 -0700
Subject: [PATCH 2/2] WIP for matthieu to play with

---
 packages/eventual-send/src/index.d.ts      |  7 +++++--
 packages/eventual-send/src/index.test-d.ts | 20 +++++++++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/packages/eventual-send/src/index.d.ts b/packages/eventual-send/src/index.d.ts
index 997dd9ec91..7c75759f6c 100644
--- a/packages/eventual-send/src/index.d.ts
+++ b/packages/eventual-send/src/index.d.ts
@@ -234,7 +234,10 @@ interface EProxy {
    * @param x target for method/function call
    * @returns method/function call proxy
    */
-  <T extends {}>(x: T): ECallableOrMethods<RemoteFunctions<T>>;
+  // <T>(x: NonNullable<T>): ECallableOrMethods<RemoteFunctions<T>>;
+  // (undefined): Record<PropertyKey, never>;
+  // (x: null): Record<PropertyKey, never>;
+  <T>(x: NonNullable<T>): ECallableOrMethods<RemoteFunctions<T>>;
 
   /**
    * E.get(x) returns a proxy on which you can get arbitrary properties.
@@ -245,7 +248,7 @@ interface EProxy {
    * @param x target for property get
    * @returns property get proxy
    */
-  readonly get: <T extends {}>(x: T) => EGetters<LocalRecord<T>>;
+  readonly get: <T>(x: T) => EGetters<LocalRecord<T>>;
 
   /**
    * E.resolve(x) converts x to a handled promise. It is
diff --git a/packages/eventual-send/src/index.test-d.ts b/packages/eventual-send/src/index.test-d.ts
index a96fed2fe0..84353f33b7 100644
--- a/packages/eventual-send/src/index.test-d.ts
+++ b/packages/eventual-send/src/index.test-d.ts
@@ -1,5 +1,6 @@
 /* eslint-disable @endo/no-polymorphic-call, import/no-extraneous-dependencies, no-restricted-globals, prettier/prettier */
 import { expectType } from 'tsd';
+import { Far } from '@endo/marshal';
 import { E } from '../test/get-hp.js';
 import { DataOnly, ERef } from './index.js';
 
@@ -51,13 +52,30 @@ const foo2 = async (a: FarRef<{ bar(): string; baz: number }>) => {
 type SomeRemotable = { someMethod: () => 'hello'; someVal: 'alsoHello' };
 const undefinedCase = () => {
   let ref: SomeRemotable | undefined;
+  // @ts-expect-error can't proxy an undefined value
+  E(ref);
   // @ts-expect-error could be undefined
   E(ref).someMethod();
   // @ts-expect-error optional chaining doesn't work with E()
   E(ref)?.someMethod();
   // @ts-expect-error could be undefined
   E.get(ref);
-  const getters = E.get(ref!);
+  const getters = E.get(ref);
+  expectType < EGetters<SomeRemotable | undefined>(getters);
+  getters.someMethod.then(sayHello => sayHello());
+  getters.someVal;
+};
+const promiseUndefinedCase = () => {
+  let ref: Promise<SomeRemotable | undefined>;
+  // @ts-expect-error can't proxy an undefined value
+  E(ref);
+  // @ts-expect-error could be undefined
+  E(ref).someMethod();
+  // @ts-expect-error optional chaining doesn't work with E()
+  E(ref)?.someMethod();
+  // @ts-expect-error could be undefined
+  E.get(ref);
+  const getters = E.get(ref);
   getters.someMethod.then(sayHello => sayHello());
   getters.someVal;
 };