From fbd8633ae9f8420a589dd9bc32925418f2dde060 Mon Sep 17 00:00:00 2001
From: "Mark S. Miller" <erights@users.noreply.github.com>
Date: Tue, 30 Apr 2024 15:01:37 -0400
Subject: [PATCH] fix(base-zone,zone): import `isPassable` from
 @endo/pass-style (#9230)

closes: #XXXX
refs: https://github.com/endojs/endo/issues/2096
https://github.com/endojs/endo/pull/2042

## Description

Deleting @agoric/base-zone's implementation of `isPassable` completes
the migration of `isPassable` from @agoric/base-zone to @endo/pass-style
explained in https://github.com/endojs/endo/issues/2096 and started in
https://github.com/endojs/endo/pull/2042

The remaining issue explained in
https://github.com/endojs/endo/issues/2096 , changing how `isPassable`
is implemented, remains to be done in @endo/pass-style. But this need no
longer concern us here since that difference will now be encapsulated
from us.

### Security Considerations
None
### Scaling Considerations

We know that `passStyleOf` remains a performance hotspot that needs
attention. This PR does not affect that at all. But I'll note that the
remaining suggested change from
https://github.com/endojs/endo/issues/2096 --- to implement `isPassable`
and `passStyleOf` in terms of a more expressive internal function
parameterized by a checker --- might make this performance issue worse.
Just something to keep in mind as we tune `passStyleOf`. Attn @gibson042

### Documentation Considerations

none
### Testing Considerations

none
### Upgrade Considerations

As of this PR, @agoric/base-zone also no longer exports `isPassable`,
potentially breaking importers outside agoric-sdk until they are
modified to import it from @endo/pass-style as well. This PR does take
care of all such import sites within agoric-sdk.

If this turns out to be a problem in practice, this PR could be changed
to have @agoric/base-zone reexport the `isPassable` it imports from
@endo/pass-style, but deprecate that reexport, leaving it to future work
to change those old import sites outside agoric-sdk.

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
---
 packages/base-zone/src/heap.js        |  3 +--
 packages/base-zone/src/is-passable.js | 21 +++------------------
 packages/zone/src/durable.js          |  8 ++------
 packages/zone/src/virtual.js          |  8 ++------
 4 files changed, 8 insertions(+), 32 deletions(-)

diff --git a/packages/base-zone/src/heap.js b/packages/base-zone/src/heap.js
index 839cd2abaf1..3445255e8d5 100644
--- a/packages/base-zone/src/heap.js
+++ b/packages/base-zone/src/heap.js
@@ -1,7 +1,7 @@
 // @ts-check
 // @jessie-check
 
-import { Far } from '@endo/far';
+import { Far, isPassable } from '@endo/pass-style';
 import { makeExo, defineExoClass, defineExoClassKit } from '@endo/exo';
 import {
   makeScalarMapStore,
@@ -12,7 +12,6 @@ import {
 
 import { makeOnceKit } from './make-once.js';
 import { agoricVatDataKeys as keys } from './keys.js';
-import { isPassable } from './is-passable.js';
 
 /**
  * @type {import('./types.js').Stores}
diff --git a/packages/base-zone/src/is-passable.js b/packages/base-zone/src/is-passable.js
index 258c510c614..6a3fe59fbbe 100644
--- a/packages/base-zone/src/is-passable.js
+++ b/packages/base-zone/src/is-passable.js
@@ -1,23 +1,8 @@
-import { passStyleOf } from '@endo/pass-style';
+import { isPassable as realIsPassable } from '@endo/pass-style';
 
 /**
- * Is `specimen` Passable? This returns true iff `passStyleOf(specimen)`
- * returns a string. This returns `false` iff `passStyleOf(specimen)` throws.
- * Under no normal circumstance should `isPassable(specimen)` throw.
- *
- * TODO implement an isPassable that does not rely on try/catch, and
- * move it to @endo/pass-style.
- * This implementation is just a standin until then
- *
+ * @deprecated Import `isPassable` directly from `@endo/pass-style`
  * @param {any} specimen
  * @returns {specimen is Passable}
  */
-export const isPassable = specimen => {
-  try {
-    // In fact, it never returns undefined. It either returns a
-    // string or throws.
-    return passStyleOf(specimen) !== undefined;
-  } catch (_) {
-    return false;
-  }
-};
+export const isPassable = specimen => realIsPassable(specimen);
diff --git a/packages/zone/src/durable.js b/packages/zone/src/durable.js
index 2d248531594..75f632e9e00 100644
--- a/packages/zone/src/durable.js
+++ b/packages/zone/src/durable.js
@@ -1,7 +1,7 @@
 // @ts-check
 // @jessie-check
 
-import { Far } from '@endo/far';
+import { Far, isPassable } from '@endo/pass-style';
 import {
   canBeDurable,
   makeScalarMapStore,
@@ -14,11 +14,7 @@ import {
   provideDurableWeakSetStore,
 } from '@agoric/vat-data';
 
-import {
-  agoricVatDataKeys as keys,
-  isPassable,
-  makeOnceKit,
-} from '@agoric/base-zone';
+import { agoricVatDataKeys as keys, makeOnceKit } from '@agoric/base-zone';
 
 const { Fail } = assert;
 
diff --git a/packages/zone/src/virtual.js b/packages/zone/src/virtual.js
index 95410799db0..89a0a78a37c 100644
--- a/packages/zone/src/virtual.js
+++ b/packages/zone/src/virtual.js
@@ -1,7 +1,7 @@
 // @ts-check
 // @jessie-check
 
-import { Far } from '@endo/far';
+import { Far, isPassable } from '@endo/pass-style';
 import {
   defineVirtualExoClass,
   defineVirtualExoClassKit,
@@ -11,11 +11,7 @@ import {
   makeScalarBigWeakSetStore,
 } from '@agoric/vat-data';
 
-import {
-  agoricVatDataKeys as keys,
-  isPassable,
-  makeOnceKit,
-} from '@agoric/base-zone';
+import { agoricVatDataKeys as keys, makeOnceKit } from '@agoric/base-zone';
 
 const emptyRecord = harden({});
 const initEmpty = harden(() => emptyRecord);