Fixes #3931 (#3933)

Co-authored-by: Jarred Sumner <709451+Jarred-Sumner@users.noreply.github.com>

src/bun.js/bindings/BunString.cpp

@@ -267,47 +267,19 @@ extern "C" EncodedJSValue BunString__createArray(
     auto& vm = globalObject->vm();
     auto throwScope = DECLARE_THROW_SCOPE(vm);
 
-    if (length < 64) {
-        // We must do this or Bun.gc(true) in a loop creating large arrays of strings will crash due to GC'ing.
-        MarkedArgumentBuffer arguments;
-
-        arguments.fill(length, [&](JSC::JSValue* value) {
-            const BunString* end = ptr + length;
-            while (ptr != end) {
-                *value++ = Bun::toJS(globalObject, *ptr++);
-            }
-        });
-
-        JSC::ObjectInitializationScope scope(vm);
-        GCDeferralContext context(vm);
-
-        JSC::JSArray* array = JSC::JSArray::tryCreateUninitializedRestricted(
-            scope,
-            globalObject->arrayStructureForIndexingTypeDuringAllocation(JSC::ArrayWithContiguous),
-            length);
-
-        if (array) {
-            for (size_t i = 0; i < length; ++i) {
-                array->initializeIndex(scope, i, arguments.at(i));
-            }
-            return JSValue::encode(array);
-        }
-
+    // Using tryCreateUninitialized here breaks stuff..
+    // https://github.com/oven-sh/bun/issues/3931
+    JSC::JSArray* array = constructEmptyArray(globalObject, nullptr, length);
+    if (!array) {
         JSC::throwOutOfMemoryError(globalObject, throwScope);
         RELEASE_AND_RETURN(throwScope, JSValue::encode(JSC::JSValue()));
-    } else {
-        JSC::JSArray* array = constructEmptyArray(globalObject, nullptr, length);
-        if (!array) {
-            JSC::throwOutOfMemoryError(globalObject, throwScope);
-            RELEASE_AND_RETURN(throwScope, JSValue::encode(JSC::JSValue()));
-        }
-
-        for (size_t i = 0; i < length; ++i) {
-            array->putDirectIndex(globalObject, i, Bun::toJS(globalObject, *ptr++));
-        }
-
-        return JSValue::encode(array);
     }
+
+    for (size_t i = 0; i < length; ++i) {
+        array->putDirectIndex(globalObject, i, Bun::toJS(globalObject, *ptr++));
+    }
+
+    return JSValue::encode(array);
 }
 
 extern "C" void BunString__toWTFString(BunString* bunString)

test/js/node/fs/fs.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "bun:test";
 import { dirname } from "node:path";
-import { gc } from "harness";
+import { bunEnv, bunExe, gc } from "harness";
 import fs, {
   closeSync,
   existsSync,
@@ -42,6 +42,7 @@ import { join } from "node:path";
 
 import { ReadStream as ReadStream_, WriteStream as WriteStream_ } from "./export-from.js";
 import { ReadStream as ReadStreamStar_, WriteStream as WriteStreamStar_ } from "./export-star-from.js";
+import { spawnSync } from "bun";
 
 const Buffer = globalThis.Buffer || Uint8Array;
 
@@ -67,6 +68,15 @@ it("writeFileSync in append should not truncate the file", () => {
   expect(readFileSync(path, "utf8")).toBe(str);
 });
 
+it("await readdir #3931", async () => {
+  const { exitCode } = spawnSync({
+    cmd: [bunExe(), join(import.meta.dir, "./repro-3931.js")],
+    env: bunEnv,
+    cwd: import.meta.dir,
+  });
+  expect(exitCode).toBe(0);
+});
+
 it("writeFileSync NOT in append SHOULD truncate the file", () => {
   const path = join(tmpdir(), "writeFileSync-should-not-append-" + (Date.now() * 10000).toString(16));
 

test/js/node/fs/repro-3931.js

@@ -0,0 +1,4 @@
+import { readdir } from "fs/promises";
+
+const files = await readdir(`/tmp`, {});
+console.log(files.map(a => a));