fix(javascript): retain returned-reference mutation uncertainty (#1471)

src/domain/javascript/javascriptSemanticCallableResults.ts

@@ -0,0 +1,53 @@
+import * as t from "@babel/types";
+
+import { childNodes } from "./javascriptSemanticTraversal.js";
+
+/** One direct return or yield, excluding every nested callable. */
+export interface SemanticCallableResultExpression {
+  readonly node: t.Node | null;
+  readonly site: t.Node;
+  readonly kind: "return" | "yield";
+  readonly delegated: boolean;
+}
+
+/** Collect direct result syntax without executing or evaluating a callable. */
+export const semanticCallableResultExpressions = (
+  callable: t.Node,
+): readonly SemanticCallableResultExpression[] => {
+  if (
+    t.isArrowFunctionExpression(callable) &&
+    !t.isBlockStatement(callable.body)
+  )
+    return [
+      {
+        node: callable.body,
+        site: callable.body,
+        kind: "return",
+        delegated: false,
+      },
+    ];
+  if (!t.isFunction(callable)) return [];
+  const output: SemanticCallableResultExpression[] = [];
+  const pending = childNodes(callable.body).reverse();
+  while (pending.length > 0) {
+    const node = pending.pop();
+    if (node === undefined || t.isFunction(node) || t.isClass(node)) continue;
+    if (t.isReturnStatement(node)) {
+      output.push({
+        node: node.argument ?? null,
+        site: node,
+        kind: "return",
+        delegated: false,
+      });
+    }
+    if (t.isYieldExpression(node))
+      output.push({
+        node: node.argument ?? null,
+        site: node,
+        kind: "yield",
+        delegated: node.delegate,
+      });
+    for (const child of childNodes(node).reverse()) pending.push(child);
+  }
+  return output;
+};