[BUGFIX] Do not eagerly consume modifier args during destruction

Currently, in the 3.13 modifier capabilities version, we eagerly consume
the arguments that are passed to the modifier when it is destroying.
This can cause issues with backtracking rerender when the state isn't
actually used, and neither is the consumption. This change makes it so
that we don't eagerly consume these arguments during destruction in
general.

package.json

@@ -43,7 +43,7 @@
     "typescript": "4.0.2"
   },
   "dependencies": {
-    "@handlebars/parser": "^2.0.0",
+    "@handlebars/parser": "~2.0.0",
     "@simple-dom/document": "^1.4.0",
     "@simple-dom/interface": "^1.4.0",
     "@simple-dom/serializer": "^1.4.0",

packages/@glimmer/integration-tests/test/managers/modifier-manager-test.ts

@@ -234,6 +234,52 @@ abstract class ModifierManagerTest extends RenderTest {
       /You attempted to update `foo` on `.*`, but it had already been used previously in the same computation/
     );
   }
+
+  @test
+  'does not eagerly access arguments during destruction'(assert: Assert) {
+    class Foo extends CustomModifier {}
+
+    let foo = this.defineModifier(Foo);
+
+    let Main = defineComponent(
+      { foo },
+      '{{#if @state.show}}<h1 {{foo @state.bar [email protected]}}>hello world</h1>{{/if}}'
+    );
+
+    let barCount = 0;
+    let bazCount = 0;
+
+    class State {
+      @tracked show = true;
+
+      get bar() {
+        if (this.show === false) {
+          barCount++;
+        }
+
+        return;
+      }
+
+      get baz() {
+        if (this.show === false) {
+          bazCount++;
+        }
+
+        return;
+      }
+    }
+
+    let state = new State();
+
+    this.renderComponent(Main, { state });
+
+    state.show = false;
+
+    this.rerender();
+
+    assert.equal(barCount, 0, 'bar was not accessed during detruction');
+    assert.equal(bazCount, 0, 'baz was not accessed during detruction');
+  }
 }
 
 class ModifierManagerTest313 extends ModifierManagerTest {

packages/@glimmer/manager/lib/public/modifier.ts

@@ -112,7 +112,8 @@ export class CustomModifierManager<O extends Owner, ModifierInstance>
 
     let { useArgsProxy, passFactoryToCreate } = delegate.capabilities;
 
-    let args = useArgsProxy ? argsProxyFor(capturedArgs, 'modifier') : reifyArgs(capturedArgs);
+    let argsProxy = argsProxyFor(capturedArgs, 'modifier');
+    let args = useArgsProxy ? argsProxy : reifyArgs(capturedArgs);
 
     let instance: ModifierInstance;
 
@@ -168,7 +169,7 @@ export class CustomModifierManager<O extends Owner, ModifierInstance>
       state.debugName = typeof definition === 'function' ? definition.name : definition.toString();
     }
 
-    registerDestructor(state, () => delegate.destroyModifier(instance, state.args));
+    registerDestructor(state, () => delegate.destroyModifier(instance, argsProxy));
 
     return state;
   }

yarn.lock

@@ -1529,7 +1529,7 @@
   resolved "https://registry.yarnpkg.com/@glimmer/env/-/env-0.1.7.tgz#fd2d2b55a9029c6b37a6c935e8c8871ae70dfa07"
   integrity sha1-/S0rVakCnGs3psk16MiHGucN+gc=
 
-"@handlebars/parser@^2.0.0":
+"@handlebars/parser@^2.0.0", "@handlebars/parser@~2.0.0":
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/@handlebars/parser/-/parser-2.0.0.tgz#5e8b7298f31ff8f7b260e6b7363c7e9ceed7d9c5"
   integrity sha512-EP9uEDZv/L5Qh9IWuMUGJRfwhXJ4h1dqKTT4/3+tY0eu7sPis7xh23j61SYUnNF4vqCQvvUXpDo9Bh/+q1zASA==