Represent ordinary JavaScript arrays with hole, value, and explicit-undefined states; add sparse side storage and carry missing values through the frontend, native backends, runtime, and Node-facing consumers.
* Reuse reachability lowering output
- Retain reachable IR and assemble the emitted module without lowering bodies a second time
- Preserve reached-only artifact filtering, coverage remainder behavior, and add lowering phase timing
* Preserve record order in retained lowering
* Preserve record order in retained helpers
* Preserve generic lowering record order
* Recheck retained generic rest order
* Record retained lowering parity fixtures
* Preserve retained lowering failure parity
`.filter(fn)` required the callback to return exactly bool. JS applies
ToBoolean to whatever the predicate answers, so `xs.filter((s) => s)` — the
idiomatic drop-the-falsy — was refused for no semantic reason.
The filter loop now wraps the call in the same toBool an `if` statement would
apply. A bool answer is unchanged and emits identical IR. A union answer
routes through its interned per-arm truthy helper, requested at the call site
where a real node exists for the diagnostic. A unit-only answer is constantly
falsy, and the call still runs for its effects.
The kinds with no native ToBoolean keep the fence: void has no value at all,
and dyn/jsval/caught truthiness needs the embedded engine.
Verified against Node: filtering strings, numbers, and a
`(string | undefined)[]` all print identically in both.
Diagnostics 100, filter corpus 9 across both
backends.
* feat(string): support static split limits
- Lower split limits for string and literal RegExp separators across C and LLVM.
- Match JavaScript ToUint32 limit semantics in the runtime.
- Add differential coverage and refresh diagnostics and surface metadata.
* fix(string): default undefined split limits
* Support Date instance lowering
- Lower read-only Date values and constructors through the C and LLVM backends.
- Add portable calendar helpers, differential coverage, and documented surface contracts.
- Fence unsupported mutation, identity, locale, and component-constructor forms.
Co-authored-by: sensei-woo <sensei-woo@users.noreply.github.com>
* Fix Date exception and timezone semantics
* fix: harden Date lowering edge cases
* fix Date lowering edge cases
* Fix Date union fences and offset clipping
---------
Co-authored-by: sensei-woo <sensei-woo@users.noreply.github.com>
* fix(compiler): support implicit top-level await modules
- Match Node 24 syntax detection by treating top-level await as an ES module marker.
- Add differential corpus coverage for TypeScript files without explicit imports or exports.
* fix Node ESM classification for top-level await
* fix ESM require diagnostics and classification caching
* fix require binding and package type precedence
* fix: align top-level await module detection with Node
- Add native RequestInit, AbortSignal, and streaming request and response body support.
- Lower the static fetch surface through both C and LLVM without the embedded engine.
- Add differential, Node-typing, sanitizer, and regression coverage.
- Lower asynchronous ESM initialization with Node-compatible dependency ordering and caching.
- Finish top-level promises consistently across the C and LLVM runtimes.
- Add differential coverage for imports, rejection, and unsettled evaluation.
- Lower Number.prototype.toFixed through the compiler IR and native backends.
- Match JavaScript rounding, range errors, and numeric edge cases in the runtime.
- Add differential coverage and update surface metadata and diagnostics.
- Add Agent connection accounting and HTTP/socket compatibility surfaces
- Support dynamic Buffer at and slice access
- Pin behavior with differential corpus coverage
- The written-binding decline yields when the declared type has no mapping or the write's RHS roots at an ambient-undefined name
- A class extending a collection-poisoned base flushes the base's diagnostics eagerly: the heritage evaluates at module init, so deferring the compiler's own fence manufactured a silent wrong output
- for-of, destructuring, and spread over engine-held dyn values ride the engine's own iterator protocol with V8's exact non-iterable spellings; for-of over dyn lowers generally
- Static promises cross into the engine as thenables; Promise.all over mixed and non-literal entries runs the engine's own combinator; engine-array fulfillments exit by reference
- The re-minted silent-wrong-answer path is closed: island-literal members whose values poison fence at the read with the captured diagnostic
- The checked-dynamic tree replaces the old nickname across comments and internal docs
- trapDeclRootOf's written-binding decline now requires a mappable declared type: ordinary storage only buys anything when it compiles — an unmappable recursive call shape traded the compiling no-storage trap for a guaranteed SC2009 on a value that never exists
- bindingEverWritten skips statement-position writes whose RHS chain roots at an ambient-undefined name: that statement IS the RHS root's throw (lowerExprStatement's first claim) and never touches the target's storage, so it cannot justify the decline
- A poisoned base a top-level class extends flushes its deferred diagnostics eagerly (collectClassShape): the heritage evaluates at module init and the base's fence is the compiler's own — Node defines the base fine — so the deferred trap compiled a binary that refused at startup where Node runs; leaf and derived-only poisoned classes keep the JS deferral
- Fixtures: corpus 2632 (unmappable written trap binding) and 2633 (ambient-rooted rewrite), diagnostics js-extends-poisoned-base (the eager report names the base's real blocker), errors.test pins for both deferral edges that must NOT report eagerly; order-parity baselines recorded for the new entries
- text, json, and buffer settle real promises over the readable machinery with Node's settle timing and rejection set; arrayBuffer and blob fence with their representation reasons
- createRequire over this file's URL is compile-time plumbing: builtin specs become namespace imports, relative JSON bakes as validated documents, npm packages ride the require-condition graph, unresolvable names throw Node's catchable MODULE_NOT_FOUND
- module.builtinModules bakes as the compat target's exact list
# Conflicts:
# packages/compiler/src/frontend/lowering/lower-modules.ts
# packages/compiler/src/frontend/lowering/lowerer.ts
- The forwarding shape — emit(event, ...args) whose rest appears only as super.emit(event, ...args) — lowers per dispatching event as a real hierarchy method, vtable-participating
- error events keep the throw-when-unhandled path through overrides; super.emit resolves to the nearest override ancestor, JS's chain
- Receivers above every override route through interned instanceOf dispatch; other emitter members and stream-rooted classes keep their fences with reasons stated
# Conflicts:
# packages/compiler/test/ts7/baselines/order-parity.json
- An interval-and-wholeness inference over the lowered IR proves integrality and range for every value reaching a declared i64/u64 slot, with loop-header widening precise enough that the bounded counter loop proves its exact range
- Refusals carry the slot path, the failed obligation with evidence, and the author's concrete fix as SC4021, SC4022, and SC4023
- Declared slots are both obligation and assumption: call sites check arguments, callee bodies assume their classes; integer returns emit exact machine-integer wrappers and inbound params trap through the structured host-contract family
- Math.trunc and Math.ceil compile statically
# Conflicts:
# packages/compiler/src/library/profile.ts
- The ambient-trap probe resolves as a side-effect-free probe: deferred collection diagnostics stay deferred, and the merged-namespace fence lands as a diagnostic instead of crashing the collect walk
- deadUnmappableBinding and the nullish family claim statement-position declarators only; for-init heads and catch bindings stay locals
- Trap classification declines written bindings; the seven 0.0.10 pass-to-fail fences restore byte-identical to 0.0.9 behavior
- library-int suite snapshots SC4021/SC4022/SC4023 rendered end to end (slot path, evidence, span, fix) — the diagnostics-corpus discipline for codes the executable lane cannot reach
- dynamic-surface diagnostics fixture swaps Math.ceil for Math.sqrt (trunc/ceil compile statically now) and its snapshot regenerates
- collectGlobals' trap/nullish/dead classification probes catch PoisonError per the per-probe recovery discipline: the cross-block merged-namespace SC1090 fence reached through the ambient-root walk recorded its diagnostic and then crashed the CLI mid-discovery (5 merged-namespace corpus tests, ice bucket)
- On a poisoned probe, JS files defer the recorded diagnostics to runtime fences (deferJsCollectionDiags) and the binding falls through to ordinary registration; the statement lowering re-fences at its own site
- The no-storage binding families (nullish, dead-unmappable) only claim statement-position declarators: an uninitialized for-init let (`for (let x; false;) {}`) was claimed as dead-unmappable, violating lowerVarDeclList's contract that a for-init declarator always lowers ("lowerer bug: for-init declarator resolved to a global", 2 corpus tests)
- Fixtures: corpus 2608 (for-init heads with the masking variants), diagnostics merged-namespace-collect-probe (the collection-reached fence stays an honest SC1090)
Chris Tate