`.length` of a tuple is its arity, and the lowering folded it to that
constant only when the receiver was rooted at a binding or `this`. Any
other receiver (a call result, a ternary, an `as` assertion, an `as
const` literal) was refused with SC1090.
The receiver is now evaluated once, for its side effects and exceptions,
and its value discarded; the expression is the arity. A binding, `this`,
or a chain of plain property reads from one still folds. A chain through
an accessor is evaluated, so an accessor that returns a tuple runs, as in
Node.
`t[i]` on a fixed-shape tuple where `i` is not a literal refused with
SC1090. A tuple is a positional record, so the read now dispatches over
its arity: the element at an integer index in [0, arity), and undefined
for anything else — a fraction, a negative, NaN, Infinity, or one past
the end, exactly Node's array-like read.
The answer type is the join of the element types plus undefined, the
same policy the array index read uses, so a consumer observes a miss
like any other optional element read: `t[i]!` narrows through the
existing checked-narrow path and arithmetic on a miss is NaN. The
receiver and the index are hoisted into hidden locals when they cannot
be repeated (receiver first, since JavaScript evaluates it before the
key). The chain stays inline because the arity is a compile-time
constant, unlike the lifted array helper whose length is not.
Writes keep their fence: a stored position must be a literal index.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- Run production scope and closure capture logic with native TypeScript 7 symbols.
- Give lowering caches explicit pass ownership and stable symbol identities.
- Support reference collection arrays and optional Set seeds on both native backends.
* fix(compiler): unblock self-hosting analysis and tuple construction
- Bound type diagnostics to handle deeply nested and shared compiler types.
- Compile fixed tuple spreads and preserve const tuple inference under satisfies.
- Add native compiler-component and differential regression coverage.
* fix(tests): record tuple spread frontend parity baseline
- Record module order and preflight diagnostics for the new tuple spread regression fixture.
- console.log/info/debug/error/warn take unknown[] and render every non-scalar argument through the static util.inspect at the rest-args depth 2, strings verbatim
- top-level unions dispatch per arm at runtime with string arms raw, and util.format's %s/rest args take the same per-arm rule
- info and debug lower as stdout aliases of log; the remaining stock console members are declared in the fallback so stock-clean programs meet per-site SC2020 hints instead of a fallback-manufactured SC0001
- corpus 2440/2441 pin the widened shapes on both backends, console.log(process.argv), a find() miss union, and console.log(undefined) included
- diagnostics snapshots re-pinned: the union console fences retire and utility-types reports its real per-site fences
Chris Tate