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Use double.IsFinite instead of hand-rolled NaN and infinity pairs - #2880

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Use double.IsFinite instead of hand-rolled NaN and infinity pairs#2880
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Summary

Replace 32 hand-rolled NaN-and-infinity pairs with double.IsFinite.

Details

The bottom of this stack backfilled double.IsFinite for net462 and netstandard2.0, where it does not exist, so the whole codebase can now spell the check the way the specs phrase it. This converts the places that were open-coding it.

  • 27 were the negative form, double.IsNaN(x) || double.IsInfinity(x), almost all in Temporal and Intl argument validation → !double.IsFinite(x).
  • 4 were the positive form, including DatePrototype's private IsFinite(double) helper, which is deleted. Its DatePresentation sibling stays — that one forwards to a struct property rather than testing a double.
  • 1 needed folding by hand rather than mechanically: the remainder operator in JintExpression tested IsNaN(n) || IsNaN(d) || IsInfinity(n), which is !IsFinite(n) || IsNaN(d) with the two checks on n brought together. An infinite divisor deliberately does not produce NaN and is handled by the branch below, so only the dividend gets the full finiteness test; that is now stated in a comment rather than left to be inferred from the interleaving.

No behaviour change. On the modern target frameworks the intrinsic is a single exponent-bits test rather than two calls; on net462/netstandard2.0 the polyfill is exactly the expression it replaces, so neither leg regresses.

Linked issue

Refs #

Test plan

  • Added or updated unit tests in Jint.Tests
  • Ran dotnet test --configuration Release locally
  • For ECMAScript spec changes: ran Jint.Tests.Test262 and confirmed no regressions
  • For interop changes: covered in Jint.Tests/Runtime/Interop
  • For perf changes: included before/after numbers from Jint.Benchmark

test262 is unchanged at 99,738 passing of 99,895, 0 failed — the same numbers as the PR below, which is the point for a refactor landing mostly in Temporal and Intl, where the suite's coverage is densest. Jint.Tests 4693 / 4612, PublicInterface 1240 / 1239, CommonScripts 28 / 28, SourceGenerators 51, all green. The net472 leg is what covers the polyfill.

Breaking change?

No — pure refactor.

🤖 Generated with Claude Code

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Base automatically changed from iterator-includes to main August 1, 2026 11:08
@lahma @claude
Use double.IsFinite instead of hand-rolled NaN and infinity pairs
2cbd3bf 
The previous commits backfilled double.IsFinite for net462 and netstandard2.0,
where it does not exist, so the whole codebase can now spell the check the way
the specs phrase it. This converts the 32 places that were open-coding it.

Twenty-seven were the negative form, "double.IsNaN(x) || double.IsInfinity(x)",
almost all in Temporal and Intl argument validation, and become
"!double.IsFinite(x)". Four were the positive form, including DatePrototype's
private IsFinite(double) helper, which is deleted - its DatePresentation sibling
stays, since that one forwards to a struct property rather than testing a double.

One site needed folding by hand rather than mechanically: the remainder operator
in JintExpression tested "IsNaN(n) || IsNaN(d) || IsInfinity(n)", which is
"!IsFinite(n) || IsNaN(d)" with the two checks on n brought together. An infinite
*divisor* deliberately does not produce NaN and is handled by the branch below,
so only the dividend gets the full finiteness test; that is now stated in a
comment rather than left to be inferred from the interleaving.

No behaviour change, and on the modern target frameworks the intrinsic is a
single exponent-bits test rather than two calls. test262 is unchanged at 99,738
passing of 99,895, and the polyfill is what net462 binds to - the net472 unit
test leg covers it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
@lahma
lahma force-pushed the use-double-isfinite branch from bd08103 to 2cbd3bf Compare August 1, 2026 11:08
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lahma merged commit 718ddf9 into main Aug 1, 2026
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lahma deleted the use-double-isfinite branch August 1, 2026 11:53
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legrab added a commit to legrab/pocok that referenced this pull request Aug 18, 2026
@legrab
Bump Jint from 4.15.3 to 4.16.0 (#56)
ef20afa 
Updated [Jint](https://github.com/sebastienros/jint) from 4.15.3 to
4.16.0.

<details>
<summary>Release notes</summary>

_Sourced from [Jint's
releases](https://github.com/sebastienros/jint/releases)._

## 4.16.0

Jint 4.16.0 is a **correctness- and reliability-focused release**:
alongside asynchronous module loading, proper tail calls and four new
iterator built-ins, a pre-tag review swept the whole engine and fixed
what it found — including long-standing defects that predate this cycle.
**No option defaults changed.** Behaviour changes to note up front:
`JSON.stringify` and other machine-readable output now format
invariantly under every host culture — under Swedish or Finnish locales
on .NET 8+ it used to emit a Unicode minus sign no JSON parser accepts;
`JSON.parse` now rejects trailing commas as the grammar requires; bare
identifiers at global scope resolve through the global's prototype chain
per spec; `IModuleLoader.Resolve` is consulted once per (referrer,
specifier) pair, so a loader using it as a per-import access-control
checkpoint should move the check to `LoadModule`; and an inconsistent
sort comparator now finishes with an implementation-defined order on
every target framework instead of hanging (net462/netstandard) or
throwing a CLR exception at script (net8+).

### Highlights

**Proper tail calls (#​2975).** Strict-mode calls in tail position reuse
their frame, so `"use strict"` tail recursion runs in constant stack —
the first ES2015 PTC implementation among the .NET engines.

**Asynchronous module loading (#​2872).** `IAsyncModuleLoader` and the
`AsyncModuleLoader` template let a host fetch module source over I/O
without blocking a thread; `Engine.Modules.StartImport` returns an
operation a game loop drives via `ProcessTasks()`, and `ImportAsync`
awaits without holding a thread. The spec's load phase now exists as
written, a warm-cache async loader keeps the blocking `Import` fully
synchronous, and the blocking drain wakes on a work-arrived signal
instead of polling. A module served over a transport keeps its whole url
as `Module.Location` so its own relative imports resolve, a deferred
namespace evaluates its module instead of exposing uninitialized
bindings, and an import abandoned by a global snapshot restore reports
itself faulted instead of polling forever.

**The process no longer dies for recoverable reasons.**
`Options.LimitRecursion` used to kill the host process for most useful
limits — the constraint fired, and the unwind itself overflowed the
stack; exception filters now let it unwind ~7× deeper. The new opt-in
`Options.Constraints.StackOverflowGuard` converts unbounded recursion —
reachable through eighteen distinct routes, `new`, accessors, coercions
and Proxy traps included — from a process kill into a catchable
`RangeError`, exempting strict tail calls, which grow no stack. And a
family of CLR exceptions that escaped `engine.Evaluate` past every
script `catch` are now proper JavaScript errors or correct results:
sorting with an inconsistent comparator, destructuring with a
function-valued default (`const { onChange = () => {} } = opts`),
`toLocaleString` outside `DateTime`'s range, typed-array
`defineProperty` without a value, `DataView` reads at 2³¹,
`String.replace` `$'` with a lying exec, and the first instant of year
10000.

**New built-ins.** `Iterator.prototype.join`, `chunks`, `windows` and
`includes`; `take`/`drop` now throw `RangeError` for a finite limit
above 2^53−1 per the updated proposals.
`Intl.Locale.prototype.getCollations` reports CLDR-cited collation data
that `Intl.Collator` accepts in full, a malformed `collation` option is
a `RangeError`, and `Intl.supportedValuesOf("collation")` derives from
the same lists so the three can never drift.

**Conformance, from a review that ran what the suite does not.** Two of
the fixed defects had test262 coverage only under the never-generated
`staging/` directory, and several had none at all: `parseInt` strips the
sign before testing for a hex prefix, so `parseInt("-0x10")` is −16; a
suspended `finally` no longer swallows a pending `break`/`continue`; a
Proxy (or exotic host object) as the global's prototype answers bare
identifiers through its `get` trap; `Date.prototype.toISOString` emits
the spec's six-digit expanded year and round-trips through `Date.parse`
in every spelling including year 0; iterator helpers close their
receiver exactly once and only when the spec says so, and carry their
own `@@​toStringTag`; `Map`/`Set` `size` is the prototype accessor the
spec defines rather than a phantom own property; a Proxy's
`defineProperty` trap receives the partial descriptor the caller wrote;
a string's `@@​iterator` is read once, with the primitive as receiver;
`Array.prototype.join` re-asks the array when a side effect fills a hole
mid-join; a direct eval reaches the enclosing function's `arguments` in
both modes; and `Temporal.Now` drops the methods the proposal removed.

**Embedder surface.** `OperationDeadlineConstraint` bounds a whole
multi-entry host operation; `ScriptPreparationOptions.StaticAnalysis`
trades prepare-time analysis for per-engine materialization on shared
graphs; `ModuleFactory.LocationOf` exposes the module-naming rule a host
must match; `Engine.Advanced.HostDefined` carries per-request state on a
pooled engine; the CLR exception behind an interop error is reachable
through `JintException.TryGetClrException` with opt-in
`ChainClrExceptions()`, and a host method's own `TargetException` is no
longer mistaken for a receiver mismatch; and a recursion-limit failure
propagates out of a module load instead of becoming a catchable
rejection.

**Performance, gated.** Against v4.15.3 on idle hardware, medians of
three paired runs: `controlflow-recursive` **−15.6% time and −40.4%
allocation** (proper tail calls), `bitops-3bit-bits-in-byte` −8.9%,
`math-spectral-norm` −7.3%, `crypto-sha1` −6.9%, `3d-raytrace` −5.9%,
`math-cordic` −5.8%, with a broad −1–4% tail across the call- and
string-heavy rows; no row moved outside its own measured cross-run
envelope in the other direction, and allocation is flat within ±0.2%
suite-wide. Warmed `parseInt` call sites take the frameless fast-call
lane (−13% on the parse loop), joined by the `Number` predicates,
`String.prototype.indexOf`/`startsWith`/`endsWith`/`includes`/`at`/`substr`,
global `isNaN`/`isFinite` and `Array.isArray` (−3% to −19%) and the
`Map`/`Set` method family (`map.get` hit loop −13%); existence questions
on a wrapped dictionary answer from `ContainsKey`, taking `in` −33% with
−98% allocation and `Object.keys` −37%; resolving an inherited global no
longer allocates per miss (−99.99% on the read loop) and a global
created through an inherited write keeps the in-place store; JSON
replacer/reviver eligibility is decided once per document, built-in
callback dispatch once per loop, a call site's arguments reach an
interpreted callee in registers, and function-local `let`/`const` live
in fixed slots.

**Breaking changes.**
`Int32Extensions`/`Int64Extensions`/`DoubleExtensions` — polyfill hosts
that leaked into the public API — are now internal; on
net462/netstandard2.0, code with `using Jint;` may have bound span
`Parse`/`TryParse` members through them. `JsonParser` rejects trailing
commas. `Number.parseInt.length`/`Number.parseFloat.length` report their
spec values. Post-construction mutation of an `Options` instance no
longer reaches an already-built engine, and `Options.Configure`
callbacks work again. `UnwrapIfPromise` reports a cancelled engine as
`ExecutionCanceledException` instead of a timeout. Time-zone matching is
ASCII-case-insensitive per ECMA-402.

On the [engine comparison
benchmarks](https://github.com/sebastienros/jint/blob/main/Jint.Benchmark/README.md),
Jint 4.16.0 is the fastest engine outright on 5 of 12 scripts — leading
`dromaeo-object-regexp-modern` over native V8 by 1.25× — in a
statistical tie for first on `interop-collection-traversal`, the fastest
managed engine on 10 of 12, the fastest interpreter on all 12, and
8.6×–11.2× ahead of ClearScript (native V8) on every interop row while
allocating 3.9×–12.4× less than the nearest managed competitor.

## What's Changed
* Run the repository's own host tests under Release-mode contract
verification by @​lahma in
sebastienros/jint#2866
* Update test262 suite and implement Iterator.prototype.join by @​lahma
in sebastienros/jint#2867
* Stop a closing iterator from swallowing the error that closed it by
@​lahma in sebastienros/jint#2868
* Give every benchmark row its own engine by @​lahma in
sebastienros/jint#2873
* Hand a call site's arguments to an interpreted callee in registers by
@​lahma in sebastienros/jint#2874
* Ask once per loop, not once per element, how to call a built-in's
callback by @​lahma in sebastienros/jint#2876
* Say which spec document to read for a feature by @​lahma in
sebastienros/jint#2882
* Run PR CI on every pull request, not only those targeting main by
@​lahma in sebastienros/jint#2883
* Update test262 suite and adopt the new take/drop RangeError by @​lahma
in sebastienros/jint#2877
* Implement Iterator Chunking by @​lahma in
sebastienros/jint#2878
* Say to write against the modern BCL and polyfill downwards by @​lahma
in sebastienros/jint#2884
* Implement Iterator Includes by @​lahma in
sebastienros/jint#2879
* Ask once per document, not once per key, how to call a JSON replacer
or reviver by @​lahma in sebastienros/jint#2885
* Use double.IsFinite instead of hand-rolled NaN and infinity pairs by
@​lahma in sebastienros/jint#2880
* Bump the testing group with 1 update by @​dependabot[bot] in
sebastienros/jint#2889
* Stop charging closures for per-engine lazy globals by @​lahma in
sebastienros/jint#2890
* Bump the analyzers group with 1 update by @​dependabot[bot] in
sebastienros/jint#2888
* Make the lazy-global re-arm on restore a contract instead of an
accident by @​lahma in sebastienros/jint#2892
* Let the amortized constraint cadence span top-level entries into the
engine by @​lahma in sebastienros/jint#2886
* Let a function's own let/const live in its fixed slots by @​lahma in
sebastienros/jint#2887
* Keep a host function in the engine's own realm after a second realm
exists by @​lahma in sebastienros/jint#2893
* Make an engine's principal realm [[HostDefined]] reachable by @​lahma
in sebastienros/jint#2891
* Carry a labelled break/continue target on the completion record by
@​lahma in sebastienros/jint#2894
* Make Array.prototype.sort stable on every target framework by @​lahma
in sebastienros/jint#2898
* Stop toSorted and %TypedArray%.sort hanging on an inconsistent
comparator by @​lahma in sebastienros/jint#2899
* Delete the evaluation context's dead completion channel by @​lahma in
sebastienros/jint#2895
* Stop shipping the numeric polyfill hosts as public API by @​lahma in
sebastienros/jint#2901
 ... (truncated)

Commits viewable in [compare
view](sebastienros/jint@v4.15.3...v4.16.0).
</details>

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