From 54899bcc10742adebd05eeb00c55ee0fd7b138a3 Mon Sep 17 00:00:00 2001
From: Chris Tate <chris@ctate.dev>
Date: Sun, 25 Oct 2026 11:38:58 -0500
Subject: [PATCH] Leave factories that declare a class out of per-site clones

A class's constructor and methods are analyzed in receiver contexts
rooted at each member. Inside a per-site clone of the function that
declares the class, they resolved that function's bindings in the
default context: their writes through captured variables were lost,
and reads of the written objects folded to stale literals. A function
with a class declaration or expression anywhere inside is no longer
cloned per site.

The static-tables case adds a factory whose class method writes the
factory's object at initialization. It prints Node's `1,1,1` (it
printed `1,1,0`), and the count of constant reads stays at 8. zod3's
report is unchanged: 180 constant objects and 360 foldable reads.
---
 .../src/frontend/shape-inference/analyze.ts     | 17 +++++++++++++++++
 .../node_modules/static-tables/index.js         | 15 ++++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/packages/compiler/src/frontend/shape-inference/analyze.ts b/packages/compiler/src/frontend/shape-inference/analyze.ts
index 44d0f06a1..6722a532a 100644
--- a/packages/compiler/src/frontend/shape-inference/analyze.ts
+++ b/packages/compiler/src/frontend/shape-inference/analyze.ts
@@ -1441,6 +1441,10 @@ class Analyzer {
     // clone is its own context root, so it would resolve them in the
     // default context instead, and their writes would be lost.
     if (info.root !== null && info.root !== info.node) return null;
+    // A class's constructor and methods run in receiver contexts of their
+    // own, rooted at each member: inside a clone they too would resolve the
+    // function's bindings in the default context.
+    if (this.declaresClass(info.node)) return null;
     const sc = this.argsFrom.get(args);
     if (sc === undefined || sc.inLoop || this.forceLoop || this.repeatingSites.has(site))
       return null;
@@ -1468,6 +1472,19 @@ class Analyzer {
     return clone;
   }
 
+  private readonly classDeclarers = new Map<Node, boolean>();
+  /** Whether a class declaration or expression is anywhere inside `node`. */
+  private declaresClass(node: Node): boolean {
+    let r = this.classDeclarers.get(node);
+    if (r === undefined) {
+      const visit = (n: Node): true | undefined =>
+        ts.isClassLikeDeclaration(n) ? true : ts.forEachChild(n, visit);
+      r = ts.forEachChild(node, visit) === true;
+      this.classDeclarers.set(node, r);
+    }
+    return r;
+  }
+
   private readonly factories = new Map<Node, boolean>();
   isFactory(node: Node): boolean {
     let r = this.factories.get(node);
diff --git a/tests/fixtures/npm/cases/static-tables/node_modules/static-tables/index.js b/tests/fixtures/npm/cases/static-tables/node_modules/static-tables/index.js
index 6bae9a947..1150aff5f 100644
--- a/tests/fixtures/npm/cases/static-tables/node_modules/static-tables/index.js
+++ b/tests/fixtures/npm/cases/static-tables/node_modules/static-tables/index.js
@@ -87,8 +87,21 @@ var setBound = function () {
   this.v = 1;
 }.bind(lib.bound);
 setBound();
+// A factory that declares a class whose methods write the factory's
+// bindings.
+function makeTally() {
+  var tally = { n: 0 };
+  class Tally {
+    bump() {
+      tally.n = 1;
+    }
+  }
+  new Tally().bump();
+  return tally;
+}
+lib.tallied = makeTally();
 lib.inits = function () {
-  return lib.made.v + "," + lib.bound.v;
+  return lib.made.v + "," + lib.bound.v + "," + lib.tallied.n;
 };
 
 // A constructor function with prototype methods.