util.inspect: freeze builtInObjects to Node's 47-name bootstrap set

src/js/internal/util/inspect.js

@@ -344,12 +344,24 @@ function isURL(value) {
 
 const SymbolToPrimitive = Symbol.toPrimitive;
 
-const builtInObjects = new SafeSet(
-  ArrayPrototypeFilter(
-    ObjectGetOwnPropertyNames(globalThis),
-    e => RegExpPrototypeExec(/^[A-Z][a-zA-Z0-9]+$/, e) !== null,
-  ),
-);
+// In Node.js this set is computed at bootstrap, before any Node/Web globals
+// (Buffer, URL, Request, ...) are installed on globalThis. Bun already has
+// those globals installed when this module loads, so we freeze the exact names
+// Node v26 observes at bootstrap. A live `globalThis` scrape here would also
+// over-include SharedArrayBuffer, WebAssembly, Float16Array, DisposableStack,
+// AsyncDisposableStack and SuppressedError, which are absent from Node's
+// bootstrap global and observably change `%s` and showHidden output.
+// prettier-ignore
+const builtInObjects = new SafeSet([
+  "AggregateError", "Array", "ArrayBuffer", "Atomics", "BigInt", "BigInt64Array",
+  "BigUint64Array", "Boolean", "DataView", "Date", "Error", "EvalError",
+  "FinalizationRegistry", "Float32Array", "Float64Array", "Function", "Infinity",
+  "Int16Array", "Int32Array", "Int8Array", "Intl", "Iterator", "JSON", "Map",
+  "Math", "NaN", "Number", "Object", "Promise", "Proxy", "RangeError",
+  "ReferenceError", "Reflect", "RegExp", "Set", "String", "Symbol", "SyntaxError",
+  "TypeError", "URIError", "Uint16Array", "Uint32Array", "Uint8Array",
+  "Uint8ClampedArray", "WeakMap", "WeakRef", "WeakSet",
+]);
 
 // https://tc39.es/ecma262/#sec-IsHTMLDDA-internal-slot
 const isUndetectableObject = v => typeof v === "undefined" && v !== undefined;

test/js/node/util/node-inspect-tests/parallel/util-format.test.js

@@ -238,6 +238,24 @@
     assert.strictEqual(util.format("%s", { __proto__: null }), "[Object: null prototype] {}");
   }
 
+  // `%s` with values whose inherited `toString` comes from a non-ECMAScript
+  // built-in (Buffer, URL, ...) must call `String(value)`, not inspect it.
+  assert.strictEqual(util.format("%s", Buffer.from("ab")), "ab");
+  assert.strictEqual(util.format("%s", Buffer.from([0xe2, 0x82, 0xac])), "\u20ac");
+  assert.strictEqual(util.format("%s", new URL("http://a/b")), "http://a/b");
+  assert.strictEqual(util.format("%s", new URLSearchParams("a=1&b=2")), "a=1&b=2");
+  {
+    class MyBuffer extends Buffer {}
+    const sub = new MyBuffer(2);
+    sub[0] = 0x68;
+    sub[1] = 0x69;
+    assert.strictEqual(util.format("%s", sub), "hi");
+  }
+  // Uint8Array inherits toString from %TypedArray%.prototype, not Buffer.
+  assert.strictEqual(util.format("%s", new Uint8Array([65])), "65");
+  // ECMAScript built-ins with their own toString still take the inspect path.
+  assert.strictEqual(util.format("%s", [1, 2]), "[ 1, 2 ]");
+
   // JSON format specifier
   assert.strictEqual(util.format("%j"), "%j");
   assert.strictEqual(util.format("%j", 42), "42");

test/js/node/util/node-inspect-tests/parallel/util-inspect.test.js

@@ -20,7 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 import assert from "assert";
-import { isWindows } from "harness";
+import { isWindows, isDebug } from "harness";
 import util, { inspect } from "util";
 import vm from "vm";
 import { MessageChannel } from "worker_threads";
@@ -236,9 +236,15 @@
   );*/
 });
 
+// The surrogate-pair loop below runs ~10k util.inspect calls, which exceeds the
+// default timeout on debug+ASAN builds; prettier-ignore keeps the 3rd test() arg
+// from forcing a whole-body reindent.
+// prettier-ignore
 test("no assertion failures 2", () => {
+  // Float16Array is intentionally absent: it is not in Node's bootstrap-time
+  // `builtInObjects`, so showHidden inspects its prototype getters and the
+  // output diverges from the other typed arrays in Node as well.
   [
-    Float16Array,
     Float32Array,
     Float64Array,
     Int16Array,
@@ -270,7 +276,6 @@
 
   // Now check that declaring a TypedArray in a different context works the same.
   [
-    Float16Array,
     Float32Array,
     Float64Array,
     Int16Array,
@@ -1811,7 +1816,7 @@
     })("a");
     assert.strictEqual(util.inspect(args), "[Arguments] { '0': 'a' }");
   }
-});
+}, isDebug ? 30_000 : undefined);
 
 test("util.inspect stack overflow handling", () => {
   // Test that a long linked list can be inspected without throwing an error.