fix(runtime): an Error subclass has a .stack and an [object Error] tag (from #9432)

changelog.d/9410-error-subclass-stack.md

@@ -0,0 +1,77 @@
+### Fixed
+
+- **An `Error` subclass now has a `.stack` and reports `[object Error]`.**
+  `class A extends Error {}` produced instances whose `.stack` was `undefined`
+  and whose `Object.prototype.toString` tag was `"[object Object]"`. The base
+  class was fine — `new Error("x").stack` has always been a string — so only
+  subclasses were affected, and the claude-code bundle has **93** of them and
+  **106** `.stack` reads. `claude doctor` printed ~10 real frames and 14,573
+  bytes of stderr under node; under perry it printed ` -     at <anonymous>`
+  and 120 bytes. Silent: no error, just a missing trace.
+
+  One root cause behind both symptoms. `class A extends Error {}` deliberately
+  produces an ordinary `GC_TYPE_OBJECT` class instance rather than a
+  `GC_TYPE_ERROR` `ErrorHeader`, so that the subclass's own fields have
+  somewhere to live. `alloc_error` — the only place that fills
+  `ErrorHeader.stack` — is therefore never reached, and neither is any
+  `stack` on `Error.prototype`, which carries only `name` and `message`. The
+  `[object Error]` branch of `js_object_to_string` is keyed on that same GC
+  header byte, so a subclass fell through to the `class_id` block and out the
+  `"[object Object]"` default.
+
+  The class-id registry that answers this question already existed and was
+  wired at four other sites — `instanceof Error`, `util.types.isNativeError`,
+  `Error.prototype.toString`'s subclass arm, and prototype-chain resolution
+  all consult `extends_builtin_error(class_id)`. Neither the tag nor the stack
+  did.
+
+  - `crates/perry-runtime/src/object/to_string_tag.rs` — tag a
+    `extends_builtin_error` class instance `"Error"`, set *before* the
+    `Symbol.toStringTag` hook so a subclass's own tag still wins (§20.1.3.6
+    consults the tag property last).
+  - `crates/perry-runtime/src/error_subclass_stack.rs` (new; `error.rs` was
+    within 90 lines of the 2,000-line CI cap) — `js_error_subclass_capture_stack`
+    installs the own, non-enumerable, configurable `stack` accessor node
+    installs, capturing the FRAME at the construction site. The head
+    (`"name: message"`) is formatted on read, not at capture, because that is
+    what V8 does and what the ubiquitous
+    `constructor(m) { super(m); this.name = "X" }` shape needs: node reports
+    `"X: m"`, and the assignment happens after `super()` returns. A user
+    `Error.prepareStackTrace` still wins, as it does for
+    `Error.captureStackTrace`. The setter redefines `stack` as a plain data
+    property, so `err.stack = ""` keeps working.
+  - `crates/perry-runtime/src/object/class_constructors.rs` — install it from
+    `js_error_subclass_default_init` (the synthesized standalone ctor, which
+    also serves the dynamic-parent `super` path) and from
+    `default_error_init_for_implicit_chain` (the dynamic `new` replay), the
+    two runtime sites that already stamped `message`/`name` and stopped there.
+    In the replay the install is moved above the message guard, which returns
+    early for a no-argument `new X()` — exactly the instances that would
+    otherwise still have no trace.
+  - `crates/perry-codegen/src/expr/this_super_call.rs`,
+    `crates/perry-codegen/src/lower_call/new_error_init.rs` (new; the
+    static-`new` Error arm moved out of `new.rs`, which was 5 lines from the
+    2,000-line CI gate) — the same call from the two codegen sites that stamp
+    `message`/`name` inline: an explicit `super(message)` into a built-in
+    Error, and the static-`new` arm for a subclass with no own constructor.
+    `this` is reloaded from its slot first; the stamps above it can collect.
+
+  A unit test in the new module installs the accessor under forced evacuation,
+  which is the only condition that can expose an unrooted pointer — and which
+  caught the first cut of that rooting reading a NaN-box handle back with
+  `get_raw_const_ptr`, aborting every Error-subclass construction with
+  "runtime handle kind mismatch". Nothing in the unit suite constructed an
+  Error subclass before, so only a compiled probe saw it.
+
+  Validation: `test-files/test_gap_9410_error_subclass_stack.ts`
+  byte-compared against `node --experimental-strip-types` across a bare
+  subclass, a `this.name`-assigning subclass, one with an extra field, a
+  two-level subclass, a subclass that sets `message` after an argument-less
+  `super()`, `TypeError`/`RangeError` subclasses, a factory-constructed
+  instance, a caught throw, `Error.captureStackTrace` on a subclass, and
+  controls for the base `Error`, a non-Error class and a plain object. The
+  fixture asserts the portable parts of the contract — `typeof stack`, the
+  head line, the `toString` tag, `name`/`message`/`instanceof`, and that
+  `stack` is an own but non-enumerable property that stays out of
+  `Object.keys` — because stack CONTENTS are host-specific. Demonstrated
+  failing on a compiler built from unfixed `origin/main` (46 diverging lines).

changelog.d/9412-cjs-entry-next-tick-order.md

@@ -0,0 +1,66 @@
+### Fixed
+
+- **A `require()` of a builtin no longer demotes `process.nextTick` below
+  promise microtasks.**
+
+  ```js
+  require("path");                 // delete this line and perry matched node
+  const o = [];
+  process.nextTick(() => o.push("nextTick"));
+  Promise.resolve().then(() => o.push("p1"));
+  (async () => { await null; o.push("await"); })();
+  setTimeout(() => console.log(JSON.stringify(o)), 20);
+  // node:  ["nextTick","p1","await"]
+  // perry: ["p1","await","nextTick"]   (5/5 deterministic)
+  ```
+
+  The deferral itself is correct, and measurement says so: the same file run
+  by node 26 as `.cjs` prints `["nextTick","p1","await"]`, as `.mjs`
+  `["p1","await","nextTick"]`. An ES module evaluates inside its module job's
+  promise chain, so its first tick drain lands after the promise queue — which
+  is exactly what `js_mark_entry_module_esm` (#788) models. It was being
+  applied to the wrong module kind.
+
+  Entry codegen decided "is this an ES module?" with
+  `!hir.imports.is_empty() || !hir.exports.is_empty() || has_top_level_await`.
+  A bare `require(` with no top-level `import` classifies the entry as
+  CommonJS, and `cjs_wrap` then rewrites it to ESM — injecting
+  `import { createRequire as __perry_cjs_create_require } from 'node:module'`
+  and `export default _cjs`. Both halves of that predicate became true for
+  every CommonJS program. The `require("path")` call itself contributes no
+  import at all; it folds to a native-module reference. Every real bundle
+  requires a builtin and every minimal fixture does not, so the ordering was
+  right in exactly the programs a test suite contains and wrong in exactly the
+  programs users run.
+
+  - `crates/perry-codegen/src/collectors/cjs_scaffolding.rs` —
+    `is_cjs_wrapped_module`, keyed on the local name the wrap's synthetic
+    `createRequire` import binds. Recognised from the HIR, not from an
+    expectation about the template: if the wrap stops emitting it the
+    predicate degrades to "not wrapped" (today's behaviour) rather than to a
+    wrong answer for hand-written ESM, and a user's own
+    `import { createRequire } from 'node:module'` is not mistaken for it
+    because the match is on the alias, not the specifier.
+  - `crates/perry-codegen/src/codegen/entry.rs` — gate only the
+    `js_mark_entry_module_esm` call on that. The `is_esm_entry` below it keeps
+    its meaning for GlobalDeclarationInstantiation: a CommonJS module's
+    top-level `function` declarations live inside the module wrapper and are
+    not global-object properties either, so "not a Script" stays the right
+    answer there — and that predicate is mirrored in `perry-hir`'s
+    `lower_module_fn`, which runs before the wrap flag is knowable in codegen.
+  - `crates/perry/src/commands/compile/cjs_wrap/preamble_canary_tests.rs` —
+    a template canary in the same family as #7139/#7152: rename the local in
+    `wrap.rs` and every CommonJS entry silently goes back to ES-module tick
+    ordering with nothing going red. Plus a negative control, so the fix
+    cannot drift the other way and give real ESM entries CommonJS ordering.
+
+  Validation: `test-files/test_gap_9412_require_builtin_tick_order.cts`
+  byte-compared against node — ticks first, a tick scheduled from inside a tick
+  joining the same drain, a tick scheduled from inside a microtask landing
+  after it, and a second event-loop turn where no evaluation checkpoint could
+  apply. It has to be a `.cts`: this repo is `"type": "module"`, so a plain
+  `.ts` is an ES module for node and perry alike and cannot carry the shape
+  (#9418 taught the runner to discover `.cts`).
+  `test-files/test_gap_9412_entry_tick_order.ts` pins the ESM side so the fix
+  cannot be "stop deferring, always". Demonstrated failing on a compiler built
+  from unfixed `origin/main`.

crates/perry-codegen/src/codegen/entry.rs

@@ -1046,7 +1046,31 @@ pub(super) fn compile_module_entry(
         // first microtask drain finishes promise/queueMicrotask jobs before
         // the nextTick queue, matching Node's job-within-checkpoint ordering
         // for ESM evaluation (#788). CJS-style entries keep ticks-first.
-        if !hir.imports.is_empty() || !hir.exports.is_empty() || hir.has_top_level_await {
+        //
+        // #9412: "has imports or exports" is not the same question for a
+        // CommonJS entry, because `cjs_wrap` gives every CommonJS file BOTH —
+        // a synthetic `import { createRequire as __perry_cjs_create_require }
+        // from 'node:module'` and an `export default _cjs`. So any entry
+        // containing a bare `require(` answered "ESM" here and ran its
+        // `process.nextTick` callbacks AFTER the promise queue, where Node
+        // runs a CommonJS program's ticks first. Measured against Node 26:
+        // an entry as `.cjs` prints ["tick","promise","await"], the same file
+        // as `.mjs` prints ["promise","await","tick"] — the deferral is right,
+        // it was just being applied to the wrong module kind. Every real
+        // bundle requires a builtin and every minimal fixture doesn't, so the
+        // ordering was correct in exactly the programs a test suite contains.
+        //
+        // Only this checkpoint is re-gated. `is_esm_entry` below keeps its
+        // original meaning for GlobalDeclarationInstantiation: a CommonJS
+        // module's top-level `function` declarations live inside the module
+        // wrapper and are NOT global-object properties either, so "not a
+        // Script" is the right answer there for a wrapped entry too — and
+        // that predicate is mirrored in `perry-hir`'s `lower_module_fn`,
+        // which runs before the wrap flag is knowable here.
+        let cjs_wrapped_entry = crate::collectors::is_cjs_wrapped_module(hir);
+        if (!hir.imports.is_empty() || !hir.exports.is_empty() || hir.has_top_level_await)
+            && !cjs_wrapped_entry
+        {
             ctx.block().call_void("js_mark_entry_module_esm", &[]);
         }
         // Initialize static class fields with their declared init

crates/perry-codegen/src/collectors/cjs_scaffolding.rs

@@ -617,6 +617,44 @@ fn for_each_stmt(stmts: &[Stmt], f: &mut dyn FnMut(&Stmt)) {
     }
 }
 
+/// The local name `cjs_wrap` binds its synthetic `createRequire` import to.
+///
+/// Mirrors the `imports` prefix in
+/// `perry/src/commands/compile/cjs_wrap/wrap.rs` — a wrapped module always
+/// opens with
+/// `import { createRequire as __perry_cjs_create_require } from 'node:module';`
+/// and nothing else in the pipeline ever mints that local. The `perry` crate's
+/// template canary
+/// (`commands/compile/cjs_wrap/preamble_canary_tests.rs`) asserts the wrap
+/// still emits it, so a template edit fails a test instead of silently
+/// un-recognising every CommonJS entry.
+pub const CJS_WRAP_CREATE_REQUIRE_LOCAL: &str = "__perry_cjs_create_require";
+
+/// True when `module` is the output of `cjs_wrap`'s CommonJS-to-ESM rewrite
+/// rather than a module the user wrote with `import`/`export`.
+///
+/// #9412: `is_esm_entry` asks "does this module have imports or exports?", and
+/// the wrap gives EVERY CommonJS file both — a synthetic `node:module` import
+/// and an `export default _cjs`. A CommonJS entry therefore answered "yes" and
+/// took Node's *ES-module* `process.nextTick` ordering (ticks after the promise
+/// queue drains) when Node runs it with *CommonJS* ordering (ticks first).
+///
+/// Recognised from the HIR, not from an expectation about the wrap template:
+/// if the template stops emitting this binding the predicate degrades to
+/// "not wrapped" — today's behaviour — rather than to a wrong answer for
+/// hand-written ESM.
+pub fn is_cjs_wrapped_module(module: &Module) -> bool {
+    module.imports.iter().any(|import| {
+        import.specifiers.iter().any(|specifier| {
+            matches!(
+                specifier,
+                perry_hir::ImportSpecifier::Named { local, .. }
+                    if local == CJS_WRAP_CREATE_REQUIRE_LOCAL
+            )
+        })
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::super::ptr_shape::collect_shape_proven_ptr_locals;

crates/perry-codegen/src/collectors/mod.rs

@@ -57,7 +57,10 @@ mod this_as_value;
 mod uppercase_strings;
 
 // Public re-exports for the visible API.
-pub use cjs_scaffolding::{census as cjs_preamble_census, CjsPreambleCensus};
+pub use cjs_scaffolding::{
+    census as cjs_preamble_census, is_cjs_wrapped_module, CjsPreambleCensus,
+    CJS_WRAP_CREATE_REQUIRE_LOCAL,
+};
 pub use clamp_detect::{detect_clamp3, detect_clamp_u8, returns_i32_identity_arg, returns_integer};
 
 // Internal-to-crate re-exports — explicit names because globs don't

crates/perry-codegen/src/expr/this_super_call.rs

@@ -1327,6 +1327,26 @@ pub(crate) fn lower(ctx: &mut FnCtx<'_>, expr: &Expr) -> Result<String> {
                                     &[(I64, &this_handle), (DOUBLE, opts_val)],
                                 );
                             }
+                            // #9410: `stack`. `super(message)` into a built-in
+                            // Error stamps `message`/`name`/`cause` onto the
+                            // already-allocated plain instance and stops there,
+                            // so `new (class extends Error {})("x").stack` was
+                            // `undefined` while `new Error("x").stack` is a
+                            // string. The frame is captured HERE, at the
+                            // construction site; the `name: message` head is
+                            // formatted on read, because a subclass
+                            // constructor assigns `this.name` after `super()`
+                            // returns and Node reports the assigned name.
+                            let blk = ctx.block();
+                            // Reload `this` from its slot: the stamps above
+                            // can collect, and a DOUBLE held across a
+                            // collecting call is the bare-pointer hazard
+                            // #8770 is about.
+                            let this_for_stack = blk.load(DOUBLE, &this_slot);
+                            blk.call_void(
+                                "js_error_subclass_capture_stack",
+                                &[(DOUBLE, &this_for_stack)],
+                            );
                         }
                     }
                     bind_derived_this_after_super(ctx);

crates/perry-codegen/src/lib.rs

@@ -218,3 +218,25 @@ pub fn module_exported_return_shapes(
 pub fn cjs_preamble_census(hir: &perry_hir::Module) -> CjsPreambleCensus {
     collectors::cjs_preamble_census(hir)
 }
+
+/// #9412 template-change canary: the local name `cjs_wrap` binds its synthetic
+/// `createRequire` import to.
+///
+/// [`crate::collectors::is_cjs_wrapped_module`] keys the CommonJS-entry
+/// recognition on this name, and the entry codegen keys the
+/// `process.nextTick`-vs-microtask ordering on that. The `perry` crate's
+/// template canary asserts the wrap still emits it, so a template edit fails a
+/// test rather than silently putting every CommonJS entry back on ES-module
+/// tick ordering.
+pub fn cjs_wrap_create_require_local() -> &'static str {
+    collectors::CJS_WRAP_CREATE_REQUIRE_LOCAL
+}
+
+/// #9412: is `hir` the output of `cjs_wrap`'s CommonJS-to-ESM rewrite?
+///
+/// Public for the `perry` crate's template canary, alongside
+/// [`cjs_wrap_create_require_local`]. The compile pipeline reaches the same
+/// predicate through `collectors::is_cjs_wrapped_module`.
+pub fn module_is_cjs_wrapped(hir: &perry_hir::Module) -> bool {
+    collectors::is_cjs_wrapped_module(hir)
+}

crates/perry-codegen/src/lower_call/mod.rs

@@ -80,6 +80,7 @@ mod native_table;
 mod new;
 pub(crate) mod new_alloc;
 mod new_ctor_args;
+mod new_error_init;
 mod new_helpers;
 pub(crate) use new_helpers::emit_ctor_return_override;
 mod omitted_native_params;