Readable, Writable, Duplex, Transform and PassThrough take the
objectMode option, and a Duplex, Transform or PassThrough the
readableObjectMode and writableObjectMode options, as true or false
literals in an options object literal or in an options value. An
object-mode side holds any value that converts to a checked-dynamic
value: push, unshift, write, end, pipe, pipeline, for await, 'data'
listeners, Readable.from and the transform callback carry values in
TypeScript and JavaScript, and constructor-function streams and options
held in variables do the same. The object-mode high-water mark counts
values and defaults to 16. A readable buffer that mixes strings, Buffers
and other values holds them all, and push(undefined) and other values on
a byte-mode stream report ERR_INVALID_ARG_TYPE through 'error', as in
Node.
In typed code a write or transform callback, or a _write or _transform
method, may declare its chunk with any such type, which converts when
the callback runs. Writes pass the encoding argument to _write and
_transform as Node does: undefined when absent, null when a callback
took its place, otherwise the value unchanged. A parameter declared
string | null | undefined receives that value and one declared string
receives "" for undefined and null. write(chunk, encoding) on a
byte-mode stream encodes a string chunk with any known encoding and
throws ERR_UNKNOWN_ENCODING for an unknown one. Readable.from takes
typed Maps and Sets of any such value, and arrays that mix strings and
Buffers.
for await over a readable-only stream that will emit 'close' now ends
after 'close', as Node's eos does. Buffered writes that complete inside
clearBuffer run their callbacks in order, and 'finish' waits for a
deferred afterWrite that carries a callback, as Node's pendingcb does,
unless a _final callback schedules it.
The 'data' listener adapters take three slots and write and transform
callbacks read their chunk and encoding through runtime accessors, so
RUNTIME_ABI_VERSION is now 26.
Cipheriv and Decipheriv values are Transforms, as in Node: they can be
written and ended, piped into, used as pipeline() and stream/promises
pipeline stages, composed, read, iterated with for await, read by
stream/consumers, passed to finished(), and listened to, and their stream
properties read as in Node. Each chunk goes through the cipher's
update(), and the end pushes final() or reports its error through
'error'; writing after final() throws out of write(). The stream unit
builds a cipher's Transform on its first stream use from operations the
cipher's handle provides (ScrDynHandleOps.transform), so programs that
use ciphers without streams link as before. The cipher is a
collector-headered object behind a traced handle: its Transform's steps
hold it, and the pair is reclaimed as a cycle. Through untyped values, in
a program that uses streams, a cipher's stream properties and its on,
once, off, pipe, unpipe, read, pause, resume, setEncoding, write, end,
destroy, cork and uncork members run on its Transform; other stream
members throw a coded SC2020 error.
A Transform holds a write's callback while its readable side is at the
high-water mark and runs it at the next read, and runs it on a tick once
the readable side has ended, as Transform._write does. write() on a
PassThrough, a Transform, a Hash or a cipher used to return true however
much the readable side buffered. zlib streams applied the rule already
and keep their timing.
pipeline() accepts function stages anywhere among its streams, so runs of
async generator stages can sit on both sides of a stream. A stage can be
named by a function declaration, or a const bound to a function
expression, that nothing reassigns; its body lowers again at the
pipeline with its source typed by the pipeline. The source can also be
an array, a string, a synchronous generator object, or a synchronous
generator function without parameters: an async generator steps the
source's iterator and yields each element, and the next stage receives
each element on the same tick as with Node's for await over the source.
The runtime's function-stage entry points take a bitmask of the function
positions and one (next, read, return) helper triple for each generator
pumped into a stream, so RUNTIME_ABI_VERSION is now 25. In JavaScript,
the chunks a stage receives from the previous stage's generator read as
the strings or Buffers it yields, so their string and Buffer methods
compile.
Corpus 7055-7059 cover cipher streams in TypeScript and JavaScript, their
errors, close order and backpressure, the pipeline stages and sources
with their tick order, and Transform backpressure.
execa 5 mixes then/catch/finally into a real ChildProcess with
Reflect.defineProperty, replaces kill and adds cancel by assignment, and
awaits the child.
- A new optional runtime unit, scr_dyn_handle_props.c, keeps those
properties in a side table keyed by the native child. Wrapper ops for
the child tag look there first for reads, member calls and writes.
defineProperty and getOwnPropertyDescriptor use it, and await adopts a
child with a callable then. Class methods read as values call the
class's own method.
- In JavaScript files, writes onto typed children, reads and calls of
added names, method values for bind/call/apply, and members no typed
lowering claims go through the child's checked-dynamic box.
- Only programs whose JavaScript adds properties to children link the
unit and install the table; everything else compiles as before.
- A setTimeout delay that may be a boolean converts with ToNumber, and
`if (t.unref)` over a timer handle folds to true (execa's lib/kill.js).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
crypto.createECDH returns a native ECDH handle backed by mbedTLS for
prime192v1, secp224r1, prime256v1, secp384r1, secp521r1, secp192k1,
secp224k1, secp256k1, brainpoolP256r1, brainpoolP384r1 and
brainpoolP512r1. generateKeys, computeSecret, getPublicKey,
getPrivateKey, setPrivateKey, setPublicKey and ECDH.convertKey follow
Node 24: compressed, uncompressed and hybrid points, input and output
encodings, the private key range, key pair validation, and Node's error
codes and messages.
Curve names follow OpenSSL's short-name lookup: names of other curves
from crypto.getCurves() are refused at compile time when literal and
throw a coded SC2020 error when computed, other OpenSSL short names
throw ERR_CRYPTO_OPERATION_FAILED, and unknown names throw
ERR_CRYPTO_INVALID_CURVE. Calls whose arguments no @types/node overload
accepts, and computeSecret(view, encoding), are refused at compile time.
The runtime unit scr_ecdh.c links, with the mbedTLS archive, only into
programs that use ECDH. wasm32-wasi builds refuse it.
hot-shots, a StatsD client compiled from its JavaScript, failed when a
program constructed a client. Each gap on its UDP path is closed
generically:
- Sloppy-mode functions with named parameters may read `arguments`
where the aliasing of their parameters cannot show: only
`arguments.length`, or element reads without parameter or element
writes.
- An `any` slot admits any boxable function value, including functions
with optional parameters (`C.prototype.m = function (...)` through an
untyped receiver).
- In a JavaScript file TypeScript does not check, a prototype method
takes its documented parameters as checked-dynamic values, as
constructors already did.
- JavaScript dgram sends run completion callbacks, buffer lists,
connected sends and the six-argument offset/length form.
- A dgram socket crosses into the checked-dynamic tree as a handle
(SCR_DYNH_DGRAM_SOCKET) whose methods are function values, with
untyped listeners that survive 'close'. The handle lives in its own
runtime unit (scr_dgram_dyn.c, the dgramDyn feature), linked only
when a program converts a socket to or from an untyped value.
- `String.prototype.concat` on strings, and `parseInt` over a possibly
missing or untyped value in JavaScript.
Corpus programs 6590-6596 and the hot-shots-udp npm
case (hot-shots 8.5.0 vendored) match Node in both lanes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- A JavaScript generator whose inferred return is `any` (it delegates to
itself) is a generator with checked-dynamic channels.
- for await over a checked-dynamic value: a compiled async generator, the
value's Symbol.asyncIterator result, or its synchronous iterator with
awaited values; break and throws close it through an awaited return().
A value that is not iterable throws V8's TypeError.
- yield* in async generators delegates through the same protocol and
completes with the delegate's return value.
The runtime part is a new unit, scr_dyn_for_await.c, linked only by
programs that use it.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- bind/call/apply on builtin function values held as checked-dynamic
functions (String.fromCharCode, JSON.stringify and the forms below).
- Function values for Buffer.byteLength (Node's runtime encoding ladder),
Buffer.compare, Buffer.alloc (size check, then fill), JSON.parse,
fs.realpathSync and fs.realpathSync.native (Node's options handling).
- A JavaScript string method read as a value answers String.prototype's
function (smol-toml's `!!(''.isWellFormed)` probe).
The runtime entries live in a new unit, scr_builtin_values.c, linked only
by programs that read these values.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- A JavaScript binding written with a value whose representation differs
from its initializer's (buffer-crc32's Int32Array table) stores a
checked-dynamic value.
- A top-level JavaScript function declaration its module reassigns
(yazl's self-redefining bufferFrom) lives in a mutable module global,
assigned when the module starts; reads, calls and writes use it.
- Buffer.from with a non-literal encoding follows Node's fromString rules
at run time, and copies arrays crossing by reference; array and byte
sources ignore the extra argument.
- `new Buffer(...)` in dependency sources, where Node never warns, is
Node's construction.
- Fixed-width read/write methods on Buffers held as checked-dynamic
values dispatch through a separate runtime unit (scr_bytes_dyn.c),
linked only by programs that call them.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
pipe() into an untyped destination now comes from main's pipeIntoDyn
(stream.unboxDyn); programs with constructor-function streams unbox
through scr_dyn_builtin_stream.c, which also takes those streams, so the
separate dyn.builtinStreamPipe entry point is gone.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Bundled npm code (from2, bl, tar-stream, yazl, multistream) builds its
streams as ES5 constructor functions: util.inherits(Ctor, Readable) and
Readable.call(this, opts), with _read/_write/_transform on the
prototype. Readable.call(this) threw SC2020.
A new runtime unit, scr_dyn_builtin_stream.c (feature
dynBuiltinStream), gives the untyped stream constructors their stream
half. Base.call(this, opts) creates a runtime stream over the receiver
and keeps it in a hidden slot; the runtime calls the receiver's
underscore methods through its property lookup; the stream prototypes
carry Node's methods and accessors over the hidden stream; and
EventEmitter's methods register listeners with the runtime stream's
emitter, so runtime events and pipes reach JavaScript listeners with the
receiver as this. _readableState/_writableState are live views.
Stream class values now come from dyn.builtinStreamClass, so only
programs that use them link the stream half. Typed code sees these
objects as their runtime streams: checked casts to the stream classes
take them, readable.pipe() into an untyped destination pipes into them,
and runtime streams crossing into JavaScript answer the constructor
object.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- EventEmitter.defaultMaxListeners on the untyped constructor is Node's
accessor over the default the typed EventEmitter reads: assignments
validate as validateNumber(arg, 'defaultMaxListeners', 0) does, and
getMaxListeners() of emitters without their own limit answers the new
value.
- dyn.builtinInstanceOf and dyn.functionInstanceOf link the
constructor-function unit and the units it calls (dyn-invoke, inspect,
symbol, emitter), so a program whose only use is `this instanceof F`
links.
- The legacy pipe's cleanup runs once: when the destination emits
'close' from end(), the cleanup still queued on the source's 'end'
finds the listeners removed and emit('end') answers true.
Externrefs a guest holds are borrowed pointers. An import's result was
kept only until the outermost call returned, which was before the export
call converted its results to JavaScript, so a result created by an
import was freed before conversion. A table or global slot released the
reference it replaced at once, although the guest may still hold it in a
local after reading the slot. The kept references are now released after
the outermost caller has converted its results (scr_wasm_leave), and a
table or global store during a call keeps the reference it replaces until
then.
Checked memories (explicit bounds checks: sanitized builds, Windows)
grew with realloc, which can move the storage that memory.buffer and its
views alias. They now reserve the address space for their largest size
(mmap on POSIX hosts, VirtualAlloc on Windows) and commit pages as they
grow, so the base never moves. Hosts without address-space reservation
grow in place only until a buffer has been handed out; after that,
growth that would move the storage fails.
Tests: webassembly-externref-lifetimes.mjs (import results through an
export, table and global references replaced by the guest and by
JavaScript), webassembly-memory-growth.test.ts (views written after
growth from JavaScript and from the guest), and translate.test.ts cases
for memargs naming memory 0 explicitly and for local.tee operand types,
which b3bcbaaf7 made consistent with validation. Under SCRIPTC_SAN=1 the
two runtime tests report heap-use-after-free without these changes.
Merges main; internal/compatibility/generated/node-v24-backlog.json is
regenerated with pnpm node-compat.
events.once(emitter, name, { signal }) lowers to events.onceSignal, served
by a new runtime unit (scr_events_once_signal.c, linked only through the
eventsOnceSignal feature). It follows Node 24's lib/events.js: an
undefined signal is the plain form, a value that is not an AbortSignal
rejects with ERR_INVALID_ARG_TYPE, an aborted signal rejects with an
AbortError whose cause is signal.reason, and otherwise a once,
resist-stop-propagation 'abort' listener removes the event and 'error'
listeners and rejects. The event or the error removes the abort listener.
Options other than an object literal with one signal stay refused.
events.once now accepts stream receivers: a stream's runtime-emitted
events use their fixed tuples, and its 'data' and 'keypress' events stay
refused. A NodeJS stream interface slot that holds a stdio handle requests
the general stream representation.
Node's once is an async function that returns the executor's promise, so
its result adopts that promise through a thenable job. The plain form
settled its result two turns early; both forms now settle on Node's turn.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- matchInferSignature reads a fixed-tuple rest as its positions, so
(...args: [string, number]) needs two arguments, and a positional
any[] pattern parameter matches only when the function's parameter
there accepts an array, as TypeScript's assignability does
(corpus 6398).
- Merge origin/main (200fe8d22); node-v24-backlog.json regenerated.
Under the general stream representation, NodeJS.ReadableStream and
NodeJS.WritableStream compile as the runtime Readable and Writable
classes, so a JavaScript stream object (a constructor-function stream, a
plain object with on/pipe, a stream from bundled npm code) passed through
a TypeScript function typed with them took the checked unwrap and threw.
A program that moves an untyped value into a runtime stream class slot,
or passes an untyped pipe() destination or pipeline stage, now lowers
once more with checked-dynamic stream slots: the two interfaces (and
intersections over them) map to dyn. A native stream rides its typed
capsule and keeps its identity; any other value is the JavaScript object
itself. Member calls dispatch per value: stream.dynNative tests for a
boxed native stream, which takes the ordinary class-method lowering;
other values call their own member through dynInvoke. pipe() into a
JavaScript destination follows Node's Readable.prototype.pipe listener
protocol (stream.pipeDyn). for await and pipeline stages keep the
not-supported error for values that are not native streams.
The runtime code lives in scr_stream_dyn.c behind a new streamDyn
feature, so programs without these libCalls link the same objects.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Bundled npm code (glob, yazl, from2, multistream) subclasses Node's
classes with constructor functions: util.inherits(Ctor, EventEmitter) and
EventEmitter.call(this). util.inherits received an identity token and
threw ERR_INVALID_ARG_TYPE, EventEmitter.call(this) and
EventEmitter.prototype were refused, and `this instanceof Ctor` against
a function was refused.
A new runtime unit (scr_dyn_builtin_class.c, linked by the new
dynBuiltinClass feature) provides EventEmitter, the legacy Stream and
the stream classes as untyped constructor functions with Node's
prototype chain. EventEmitter's prototype ports lib/events.js over the
object's own _events, _eventsCount and _maxListeners properties; Stream
adds the legacy pipe. util.inherits, Base.call/apply(this, ...),
Base.prototype, instanceof on untyped values and JavaScript value reads
of these classes use them. Constructing over a stream class throws
SC2020 where it runs. instanceof against a compiled constructor function
compares its prototype with the value's prototype chain.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Main replaced the runtime-feature scan with a rule table, the executable
unit list with a unit table and the module emission with emit-module.ts:
perfLoop becomes a rule (perf.idleTime, perf.loop*, perf.eld*), a unit
(scr_perf_loop.c) and emit-module's loop-start mark (readsLoopMetrics is
now public). The feature lists take both perfLoop and main's webcrypto.
This branch's lower-exprs.ts hunks move to expressions/property-access.ts
(histogram readings), expressions/binary.ts (`??` with a function
default) and expressions/relational.ts (`in` over class members); the
caughtRead fallback stays in lower-exprs.ts.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
util.promisify(fn) over a function typed any (an npm package method typed
by its JavaScript, a bound method of an untyped value) was refused,
because the promisified signature is only known at run time. A native
wrapper now calls the function with the call's receiver, its arguments
and a callback, and answers a promise: a truthy error rejects, otherwise
the first value fulfills, the first settlement wins, and a synchronous
throw rejects. util.promisify.custom functions are not consulted.
The wrapper lives in its own runtime unit (scr_util_promisify.c), linked
by the new utilPromisify feature, so other programs are unchanged.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
ScrArr stores len and cap as 32-bit fields and no longer stores the
state pointer. The dense states share the values' allocation and run
backward from its end: the state of slot i is at
data + cap * (slot width + 1) - 1 - i. Removing slots from the front
(shift, splice(0, n)) advances data and lowers cap, which leaves every
remaining state at its address; the head room size, needed only to free
or reallocate the block, is kept in the vacated slot before data. On
64-bit targets the header goes from 64 to 48 bytes, and from 36 to 32
bytes on wasm32. Array lengths were already limited to 2^32 - 1.
The emitted code loads len and cap as i32 and zero-extends them, and
computes state addresses from data and cap. Runtime loops compute the
end of the states once per call. Local array reads load data once for
both the state and value paths. A local or strict element read whose
index is a loop's induction variable reads slots above the hole-free
prefix through the runtime: an inline state check there makes LLVM keep
-1 - i as a second induction variable, which costs a register in the
loop.
Bulk operations do not read back states they just wrote: an append to
an array whose hole-free prefix reaches its length moves the prefix bound
to the new length, a copy from below the source's prefix writes value
states without reading the source's, and releasing a string array skips
the state checks below the prefix. Copies of up to eight slots and of
short state runs use overlapping word moves instead of a call. Emitted
element access computes the state address only on the state-checked
path. Without these, programs that build many small arrays with split or
slice ran 2-4% slower than with the separate state pointer.
Integer loops over an array's length compare the counter with the i32
length field in 32 bits; the counter never exceeds 2^32 - 1 there. The
array-length stability proof accepts Map and Set reads (get, has, size)
and checked union extractions (`x!`), which run no user code, so loops
that look up maps keep the dense fast copy, which tests the hole-free
prefix once before the loop.
Small constructions with the small allocator request 6 slots, so their
blocks stay 112 bytes, now with 7 inline slots (6 after a collector
header). With 96-byte blocks of 5 slots, programs that free and reuse
many small arrays ran 15-20% slower.
RUNTIME_ABI_VERSION goes from 22 to 23.
The darwin-arm64 runtime pack matrix repeated the common matrix's base
and optional runtime source lists and its variantsFor table, so a new
runtime source needed the same line in both files. The common matrix
now exports BASE_RUNTIME_SOURCES, OPTIONAL_RUNTIME_SOURCES and
variantsFor, and the darwin-arm64 matrix imports them. A comment on the
lists notes that their order is the link order of an executable's
runtime units. Both matrices evaluate to the same objects as before.
Once generic wrappers compile (#1413), the code behind them is reachable.
This closes the general gaps found there:
- performance.eventLoopUtilization() and monitorEventLoopDelay()'s
IntervalHistogram (enable, disable, reset, percentile and the min, max,
mean, stddev, count and exceeds readings), under the fallback
declarations and @types/node. A new runtime unit, scr_perf_loop.c, links
only for programs that read them (the perfLoop feature): an unref'd
sampling interval records into HdrHistogram-shaped buckets, and
utilization measures active time as the main thread's CPU time since
the loop started.
- Catch bindings narrowed by a user type predicate or an assertion read
their members through the checked-dynamic value.
- `??` with a function default of a different signature takes the
optional callback's own function type and adapts the default.
- Optional calls on interface-typed receivers dispatch like the plain
protocol call.
- `any` parameters of function declarations and spelled function types
are checked-dynamic slots, and a generic instantiated at `any` takes
`unknown` there.
- `'key' in err` on Error receivers answers from the declaring subclasses.
- Object.entries over a generic record resolves
`keyof T extends never ? unknown : T[keyof T]` through the binding.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Chris Tate