Treat function expression deps as conditional

compiler/packages/babel-plugin-react-forget/src/ReactiveScopes/PropagateScopeDependencies.ts

@@ -63,7 +63,11 @@ export function propagateScopeDependencies(fn: ReactiveFunction): void {
       });
     }
   }
-  visitReactiveFunction(fn, new PropagationVisitor(), context);
+  visitReactiveFunction(
+    fn,
+    new PropagationVisitor(fn.env.config.enableTreatFunctionDepsAsConditional),
+    context
+  );
 }
 
 type TemporariesUsedOutsideDefiningScope = {
@@ -466,6 +470,14 @@ class Context {
 }
 
 class PropagationVisitor extends ReactiveFunctionVisitor<Context> {
+  enableTreatFunctionDepsAsConditional = false;
+
+  constructor(enableTreatFunctionDepsAsConditional: boolean) {
+    super();
+    this.enableTreatFunctionDepsAsConditional =
+      enableTreatFunctionDepsAsConditional;
+  }
+
   override visitScope(scope: ReactiveScopeBlock, context: Context): void {
     const scopeDependencies = context.enter(scope.scope, () => {
       this.visitBlock(scope.instructions, context);
@@ -547,6 +559,20 @@ class PropagationVisitor extends ReactiveFunctionVisitor<Context> {
         this.visitInstructionValue(context, id, value.value, null);
         break;
       }
+      case "FunctionExpression": {
+        if (this.enableTreatFunctionDepsAsConditional) {
+          context.enterConditional(() => {
+            for (const operand of eachInstructionValueOperand(value)) {
+              context.visitOperand(operand);
+            }
+          });
+        } else {
+          for (const operand of eachInstructionValueOperand(value)) {
+            context.visitOperand(operand);
+          }
+        }
+        break;
+      }
       default: {
         for (const operand of eachInstructionValueOperand(value)) {
           context.visitOperand(operand);

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/functionexpr–conditional-access.expect.md

@@ -2,6 +2,7 @@
 ## Input
 
 ```javascript
+// @enableTreatFunctionDepsAsConditional
 function Component(props) {
   function getLength() {
     return props.bar.length;
@@ -12,7 +13,7 @@ function Component(props) {
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
-  params: [{ bar: [] }],
+  params: [{ bar: null }],
 };
 
 ```
@@ -20,15 +21,15 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { unstable_useMemoCache as useMemoCache } from "react";
+import { unstable_useMemoCache as useMemoCache } from "react"; // @enableTreatFunctionDepsAsConditional
 function Component(props) {
   const $ = useMemoCache(5);
   let t0;
-  if ($[0] !== props.bar.length) {
+  if ($[0] !== props) {
     t0 = function getLength() {
       return props.bar.length;
     };
-    $[0] = props.bar.length;
+    $[0] = props;
     $[1] = t0;
   } else {
     t0 = $[1];
@@ -48,10 +49,10 @@ function Component(props) {
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
-  params: [{ bar: [] }],
+  params: [{ bar: null }],
 };
 
 ```
       
 ### Eval output
-(kind: ok) 0
+(kind: ok) null

compiler/packages/babel-plugin-react-forget/src/__tests__/fixtures/compiler/functionexpr–conditional-access.js

@@ -1,3 +1,4 @@
+// @enableTreatFunctionDepsAsConditional
 function Component(props) {
   function getLength() {
     return props.bar.length;
@@ -8,5 +9,5 @@ function Component(props) {
 
 export const FIXTURE_ENTRYPOINT = {
   fn: Component,
-  params: [{ bar: [] }],
+  params: [{ bar: null }],
 };