Update dependency Jint to 4.16.1

[renovate]

ℹ️ Note

This PR body was truncated due to platform limits.

This PR contains the following updates:

Package	Change	Age	Confidence
Jint	4.14.0 → 4.16.1

---

Release Notes

sebastienros/jint (Jint)

v4.16.1: 4.16.1

Jint 4.16.1 is the first release from the new 4.x maintenance branch, and it marks the point where the two lines separate: main is now 5.0.0 development, and 4.x is where the 4.16.x line continues.

What that means for you. If you are on 4.16.0, this is a drop-in update — it is correctness and conformance work only, no API change and no changed default. Every public signature is the same one 4.16.0 shipped, on all five target frameworks. If you want the 4.x line, take it from 4.x and expect fixes rather than features. If you want to follow where the engine is going, watch main — v5 brings breaking API changes, an opt-in WHATWG web API surface, Web Workers, Node compatibility and a raised .NET Framework floor, and every one of them is recorded as it lands in docs/v5-migration.md.

From this release onward the 4.x public surface is snapshotted per target framework in Jint.Tests.PublicInterface/Verify/, so "did the API move?" is a diff rather than a judgement call — on this branch a diff there is a bug, and comparing those files against main's is the v4→v5 delta.

Highlights

Conformance, from a suite that now runs more of test262. The staging/ directory is generated and executed for the first time (#​3016), which is roughly 2,800 additional cases — largely SpiderMonkey's own suite contributed upstream, covering behaviour the stable directories never reach. Much of the work below is what it found.

Built-ins do what the spec says, step by step. The array built-ins perform the internal methods they name rather than equivalents (#​3066); Array.from honours IsConstructor and a typed array's length write throws (#​3043); an array truncation walks downwards and the generics report the writes they fail (#​3072); argument validation and evaluation order are corrected in five built-ins (#​3069); Map and Set get the [[SetData]] tombstone their traversals are specified over (#​3073); Date.prototype.setTime stores the clipped time value (#​3042); and Array.prototype.values/keys/entries no longer gate on an array-like receiver (#​3236).

Iterators and control flow. A throw from the iterator step no longer closes the iterator (#​3047); the done flag is consulted before stepping again (#​3048); a rejected return() propagates out of an abandoned for await loop (#​3113); an optional-chain short circuit is distinguished from a genuine undefined (#​3040); a computed property key is evaluated even when spelled as a literal (#​3039) and survives an await or yield intact (#​3144, #​3150); and destructuring the rest of an exhausted array yields an empty array rather than 2³² elements (#​3263).

Numeric and string accuracy. Math.acosh, asinh, atanh, cbrt, expm1 and log1p are ported from fdlibm for correctly-rounded results across every target framework (#​3050); toFixed formats from the double's exact value and reads this from [[NumberData]] (#​3071); String.prototype case conversion derives from Jint's own Unicode tables rather than the host's culture data (#​3068); and the regex engine is chosen per subject, with RegExp.prototype.replace no longer rewriting lastIndex (#​3070).

Bounds that hold. JavaScript strings have a maximum length instead of a wrapped array rent (#​3015); a JSON document too long to become a string is refused while it is being built (#​3028); a frame displaced by a proper tail call keeps counting while its trampoline runs, so MaxRecursionDepth cannot be evaded by leaving and re-entering the trampoline (#​3022); and an Atomics waiter is released when nothing can ever notify it again (#​3029).

Error messages no longer run user JavaScript (#​3041) — rendering a message for a value with a script-supplied toString used to invoke it, from inside the failure path.

Internationalization. The five Temporal members the proposal removed are dropped (#​3014), and u-extension options are canonicalized with every date format the spec allows (#​3018).

Two fixes in this release come from @​svenrog — a sloppy function answering its own arguments (#​3061) and the outer link on a parked Function-constructor environment (#​3063).

What's Changed

• Drop the five Temporal members the proposal removed by @​lahma in #​3014
• Canonicalize u-extension options and format every date the spec allows by @​lahma in #​3018
• Mark a global created by an unresolvable assignment, and stop a waitAsync timeout outliving its engine by @​lahma in #​3019
• Run test262's staging/ directory too by @​lahma in #​3016
• Give JavaScript strings a maximum length instead of a wrapped array rent by @​lahma in #​3015
• Let a for-of frame decline the unwind it can only rethrow by @​lahma in #​3017
• Keep counting a frame a tail call replaced while its trampoline runs by @​lahma in #​3022
• Unpark staging/Temporal/removed-methods.js, which #​3014 already fixed by @​lahma in #​3023
• Drop the Islamic date conversions no calendar path reaches by @​lahma in #​3027
• Let an Atomics waiter go when nothing can ever notify it again by @​lahma in #​3029
• Refuse a JSON document too long to be a string while it is being built by @​lahma in #​3028
• Bump the microsoft group with 3 updates by @​dependabot[bot] in #​3033
• Bump the analyzers group with 1 update by @​dependabot[bot] in #​3031
• Add initial threat model for untrusted scripts by @​sebastienros in #​3030
• Stop ClassBenchmark rebuilding its engine per iteration by @​lahma in #​3053
• createRealm installs a full $262 on the new realm and returns it by @​lahma in #​3044
• Give the benchmark suite a measurement environment by @​lahma in #​3055
• Evaluate a computed property key even when it is spelled as a literal by @​lahma in #​3039
• Stop error messages from running user JavaScript by @​lahma in #​3041
• Array.from honours IsConstructor, and a typed array's length write throws by @​lahma in #​3043
• Consult the iterator's done flag before stepping it again by @​lahma in #​3048
• Date.prototype.setTime must store the clipped time value by @​lahma in #​3042
• Answer a sloppy function's own arguments instead of throwing by @​svenrog in #​3061
• Keep the outer link on a parked Function-constructor environment by @​svenrog in #​3063
• A throw from the iterator step must not close the iterator by @​lahma in #​3047
• Attribute a cross-realm built-in's errors and result arrays to its own realm by @​lahma in #​3049
• Distinguish an optional-chain short circuit from a genuine undefined by @​lahma in #​3040
• Update every package the solution can update, and adapt to xUnit v4 by @​lahma in #​3064
• Port fdlibm for acosh, asinh, atanh, cbrt, expm1 and log1p by @​lahma in #​3050
• Separate the permanently declined test262 exclusions from the temporary ones by @​lahma in #​3065
• Honor the receiver in an arguments object's [[Set]] and rebind a body var over a parameter by @​lahma in #​3067
• Walk an array truncation downwards, and report the writes the generics fail by @​lahma in #​3072
• Choose the regex engine per subject, and stop RegExp replace from rewriting lastIndex by @​lahma in #​3070
• Format toFixed from the double's exact value and read this from [[NumberData]] by @​lahma in #​3071
• Derive String.prototype case conversion from Jint's own Unicode tables by @​lahma in #​3068
• Write Annex B's block-function var alias when the declaration is evaluated by @​lahma in #​3076
• Settle a source-phase dynamic import with the module's [[ModuleSource]] by @​lahma in #​3074
• Warm the stack-guard recovery test before it measures depth by @​lahma in #​3080
• Maintenance: give the 4.x branch its CI, its version and its row in the README by @​lahma in #​3291
• Backport fifteen correctness and conformance fixes for 4.16.1 by @​lahma in #​3298
• Public API: record 4.x's shipped surface, so the v4 to v5 delta is a diff by @​lahma in #​3306

Full Changelog: sebastienros/jint@v4.16.0...v4.16.1

v4.16.0

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, 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 #​2866
• Update test262 suite and implement Iterator.prototype.join by @​lahma in #​2867
• Stop a closing iterator from swallowing the error that closed it by @​lahma in #​2868
• Give every benchmark row its own engine by @​lahma in #​2873
• Hand a call site's arguments to an interpreted callee in registers by @​lahma in #​2874
• Ask once per loop, not once per element, how to call a built-in's callback by @​lahma in #​2876
• Say which spec document to read for a feature by @​lahma in #​2882
• Run PR CI on every pull request, not only those targeting main by @​lahma in #​2883
• Update test262 suite and adopt the new take/drop RangeError by @​lahma in #​2877
• Implement Iterator Chunking by @​lahma in #​2878
• Say to write against the modern BCL and polyfill downwards by @​lahma in #​2884
• Implement Iterator Includes by @​lahma in #​2879
• Ask once per document, not once per key, how to call a JSON replacer or reviver by @​lahma in #​2885
• Use double.IsFinite instead of hand-rolled NaN and infinity pairs by @​lahma in #​2880
• Bump the testing group with 1 update by @​dependabot[bot] in #​2889
• Stop charging closures for per-engine lazy globals by @​lahma in #​2890
• Bump the analyzers group with 1 update by @​dependabot[bot] in #​2888
• Make the lazy-global re-arm on restore a contract instead of an accident by @​lahma in #​2892
• Let the amortized constraint cadence span top-level entries into the engine by @​lahma in #​2886
• Let a function's own let/const live in its fixed slots by @​lahma in #​2887
• Keep a host function in the engine's own realm after a second realm exists by @​lahma in #​2893
• Make an engine's principal realm [[HostDefined]] reachable by @​lahma in #​2891
• Carry a labelled break/continue target on the completion record by @​lahma in #​2894
• Make Array.prototype.sort stable on every target framework by @​lahma in #​2898
• Stop toSorted and %TypedArray%.sort hanging on an inconsistent comparator by @​lahma in #​2899
• Delete the evaluation context's dead completion channel by @​lahma in #​2895
• Stop shipping the numeric polyfill hosts as public API by @​lahma in #​2901
• Give the evaluation context to the engine, and "is evaluating" its own signal by @​lahma in #​2896
• Retire the hand-rolled SkipLocalsInit and the stale PolySharp workaround by @​lahma in #​2902
• Give the target-framework guards one vocabulary by @​lahma in #​2903
• Back GetArrayDataReference so the unchecked write helpers drop their #if by @​lahma in #​2904
• Parse from spans on every target framework by @​lahma in #​2905
• Back the vectorized MemoryExtensions searches used by String, RegExp and URI code by @​lahma in #​2907
• Use the span-taking text APIs on every target framework by @​lahma in #​2908
• Backfill Dictionary.TryAdd, and stop lowercasing to look up a time zone by @​lahma in #​2909
• Backfill the remaining one-member API gaps by @​lahma in #​2910
• Build strings from spans, and retire SUPPORTS_SPAN_PARSE by @​lahma in #​2911
• Stop allocating a string[] to read one language subtag by @​lahma in #​2912
• Correct what the hand-rolled hashes say about HashCode.Combine by @​lahma in #​2913
• Say char.IsAsciiDigit where the locale parsers spelled out the range by @​lahma in #​2915
• Keep a static block's declarations out of the enclosing scope, and a class name in it by @​gkurt in #​2914
• Hold an error's CLR origin behind one reference by @​lahma in #​2916
• Cover Uint8Array base64 on a target framework that actually runs it by @​lahma in #​2920
• Keep the CLR exception behind a caught interop error by @​lahma in #​2917
• Only bind a module's own lexical declarations at module level by @​gkurt in #​2869
• Stop the host-loop timeout tests asserting that the machine never stalls by @​lahma in #​2922
• Derive the hoisting walk's module flag from the node it walks by @​lahma in #​2923
• Let a host ask for the CLR exception in the inner-exception chain by @​lahma in #​2918
• Let a module keep the whole url it was loaded from by @​gkurt in #​2871
• Document error handling in the README by @​lahma in #​2919
• Upgrade to Acornima v1.7.0 by @​adams85 in #​2924
• Resume an awaiting for-let loop into the environment it suspended in by @​HermanusMuellerEU in #​2875
• Find a registered module under the name it was registered with by @​gkurt in #​2870
• Invoke a CLR method inherited through the prototype chain on its owning instance by @​lahma in #​2928
• Bump the js-engine-comparisons group with 1 update by @​dependabot[bot] in #​2931
• Stop caching hoisting scopes for modules and block state for function bodies by @​lahma in #​2929
• Upgrade Meziantou.Analyzer to 3.0.141 by @​lahma in #​2933
• Upgrade the test262 harness tool to 1.1.1 by @​lahma in #​2934
• Fix typo in XML-doc comments by @​latent-9 in #​2932
• Let a host load modules asynchronously, as ECMA-262 already specifies by @​gkurt in #​2872
• Measure what an ES module graph costs a pooled-engine embedder by @​lahma in #​2926
• Give a multi-entry host operation one deadline the per-entry reset cannot rewind by @​lahma in #​2935
• Expose the module-location rule a host has to match by @​lahma in #​2936
• Record what a delta from the module-graph benchmark is worth by @​lahma in #​2937
• Let a host prepare a script or module without the static analysis by @​lahma in #​2938
• Document sharing a module graph across pooled engines by @​lahma in #​2940
• Treat a non-positive operation budget as no deadline rather than an expired one by @​lahma in #​2939
• Keep the chained CLR stack out of the JavaScript error string by @​lahma in #​2949
• Index the surface v4.16 added in the contract table by @​lahma in #​2943
• Document the two v4.16 surfaces the README has no line for by @​lahma in #​2942
• Stop sort throwing a CLR ArgumentException at script on net8 and net10 by @​lahma in #​2954
• Label the MyGet previews with the version they are previews of by @​lahma in #​2941
• Strip the sign before testing parseInt's argument for a hex prefix by @​lahma in #​2945
• Park a break or continue across the finally that suspends by @​lahma in #​2944
• Tell a wrong receiver apart from a host method that threw TargetException itself by @​lahma in #​2947
• Ask an exotic global prototype for a bare identifier through [[Get]] by @​lahma in #​2946
• Stamp Atomics.waitAsync's settle with the cycle that registered it by @​lahma in #​2957
• Keep the memory-limit constraint's reset total so it cannot replace a script error by @​lahma in #​2956
• Make the Math.Clamp polyfill reject inverted bounds like the BCL does by @​lahma in #​2955
• Take the operator-overloading reading after the options are applied by @​lahma in #​2948
• Decide at build time which call sites can arm the register lane by @​lahma in #​2951
• Say that prototype pollution now survives a restore as a binding by @​lahma in #​2950
• Let a host see that a restore abandoned its module import by @​lahma in #​2959
• Return JSON.parse's pooled reviver arguments when the reviver throws by @​lahma in #​2952
• Stop CreateLazy wrapping the factory the descriptor already guards by @​lahma in #​2953
• Evaluate a module Import finds in any state ModuleEvaluation accepts by @​lahma in #​2958
• Let a recursion-limit failure out of a module load instead of rejecting by @​lahma in #​2960
• Say that a host may be asked to resolve one specifier more than once by @​lahma in #​2961
• Format machine-readable output invariantly, not in the host's culture by @​lahma in #​2963
• Stop the first instant of year 10000 throwing a CLR exception out of Date by @​lahma in #​2965
• Wake the blocking promise wait on the work-arrived signal instead of polling by @​lahma in #​2966
• Emit a six-digit expanded year from Date.prototype.toISOString by @​lahma in #​2964
• Remove the rest-parameter state an arguments object can never carry by @​lahma in #​2967
• Let parseInt and parseFloat take the frameless fast-call lane by @​lahma in #​2968
• Call an iterator's return exactly once when a helper exits early by @​lahma in #​2970
• Accept the collations Intl.Locale.prototype.getCollations reports by @​lahma in #​2974
• Answer a wrapped dictionary's existence questions from ContainsKey by @​lahma in #​2969
• Stop closing an iterator whose step completed abruptly by @​lahma in #​2971
• Print a rejected iterator limit the way JavaScript prints numbers by @​lahma in #​2972
• Stop pure extension methods from shadowing Array.prototype natives by @​lahma in #​2977
• Tag iterator helper objects as Iterator Helper by @​lahma in #​2973
• Update test262 to 3655e74 and make Promise.try use PromiseResolve by @​lahma in #​2978
• Name a destructuring default only when the default was evaluated by @​lahma in #​2993
• Name the class in the constructor-without-new TypeError by @​lahma in #​2990
• Count parsed times in ticks so the last millisecond of 9999 survives by @​lahma in #​2983
• Reject a malformed collation option with a RangeError by @​lahma in #​2988
• Give the iterator helpers return's real state machine by @​lahma in #​2992
• Mark a global created through an inherited write as a mutable binding by @​lahma in #​2986
• Let a direct eval reach the enclosing function's arguments object by @​lahma in #​2979
• Keep both CLR facts when an error carries resolution info and an exception by @​lahma in #​2991
• Clamp the substitution tail the way GetSubstitution specifies by @​lahma in #​2998
• Reject a trailing comma everywhere JSON is parsed by @​lahma in #​2997
• Serve Map and Set size from the prototype accessor the spec defines by @​lahma in #​2995
• Define a typed array element without a value without crashing by @​lahma in #​2999
• Keep a DataView index whole until the spec has bounds-checked it by @​lahma in #​3000
• Read a string's iterator once, with the primitive as receiver by @​lahma in #​3002
• Hand the defineProperty trap the descriptor the caller wrote by @​lahma in #​3001
• Drop the Temporal.Now methods the proposal removed by @​lahma in #​2996
• Render a locale string for every date the spec calls valid by @​lahma in #​2981
• Parse the year the formatter is required to emit by @​lahma in #​2982
• Pin generic type arguments from the receiver, and snapshot lazy sequences on request by @​lahma in #​3004
• Implement proper tail calls for strict functions by @​sebastienros in #​2975
• Stop allocating a JsString for every inherited-global resolution by @​lahma in #​2985
• Let Map and Set lookups run frameless by @​lahma in #​2984
• Let a constraint exception unwind deep recursion without overflowing by @​lahma in #​2994
• Report the collations CLDR actually defines by @​lahma in #​2989
• Ask the array again when join meets a hole by @​lahma in #​3003
• Offer a stack-overflow guard that turns a process kill into a RangeError by @​lahma in #​3005
• Derive the supported collations from the per-locale lists by @​lahma in #​3006
• Let the cheapest builtin calls run frameless by @​lahma in #​2980
• Refresh engine comparison benchmarks for 4.16.0 by @​lahma in #​3007

New Contributors

• @​latent-9 made their first contribution in #​2932

Full Changelog: sebastienros/jint@v4.15.3...v4.16.0

v4.15.3

Jint 4.15.3 rounds out the 4.15 embedder line: every item here answers friction a real integration reported while adopting the host-integration surface 4.15.0 introduced. Everything is additive — no option defaults changed and no behavior changes for existing code.

• Engine.Advanced.AddLazyGlobal (#​2862) — install a lazy global on a live engine, so a host whose globals are computed from per-request data can defer building them until script reads the name; the same PR adds Engine.Advanced.WithRestoredGlobals(snapshot, action), the try/finally every snapshot-reusing host was writing by hand.
• PropertyDescriptor.CreateLazy (#​2865) — a public lazy property descriptor that materializes once and then rejoins the read and write inline caches, which a hand-rolled CustomJsValue descriptor never could; it is the sanctioned way to build for any host object property what AddLazyGlobal does for a global.
• Options.AddImmutableCrossing(params Type[]) (#​2863) — a host promise that instances of the declared CLR types do not change while they are exposed to the engine, in exchange for which a wrapped object memoizes its resolved reads. On the nested-document walk it was built for that measures −43% to −84% time and −99% allocation against the undeclared path, with dictionary and JsonNode sources converging to identical steady-state cost. It is a promise: a declared object mutated anyway will serve stale reads.
• Host-contract verification from the shipped package (#​2864) — set the Jint.EnableHostContractVerification AppContext switch before the first use of any Jint type and the checks that catch a host answering one extension point in a way that contradicts another run in Release, throwing with a descriptive message. Embedders can now run their suites against the exact package they deploy instead of building a Debug Jint from source, and CI now runs this repository's own host suites that way too (#​2866).
• Engine.Advanced.HasSharedShape (#​2861) — a stable, pinnable predicate for whether JsObject.Create, CreateFromEntries or JsObjectShape.Instantiate actually produced a shared-layout object, which the explicitly non-contractual ObjectRepresentation diagnostic could never be.
• JsString.Create(string) is now public (#​2860) — the counterpart of JsNumber.Create, answering the empty string and single-character ASCII from interned instances instead of allocating.
• Documentation (#​2859) — an unresolvable reference's Base holds an internal sentinel rather than undefined, and resolver authors returning it were leaking that sentinel string into scripts; the docs and the in-repo sample now show the right idiom.

What's Changed

• Make JsString.Create(string) public by @​lahma in #​2860
• Document that an unresolvable reference's base is a sentinel, not undefined by @​lahma in #​2859
• Add engine-reuse ergonomics: post-construction lazy globals and a snapshot scope by @​lahma in #​2862
• Give hosts a stable predicate for "did the shaping actually happen" by @​lahma in #​2861
• Make the host-contract verifiers reachable, and complete by @​lahma in #​2864
• Give hosts a lazy descriptor that rejoins the caches once it holds a value by @​lahma in #​2865
• Let a host promise a wrapped object is immutable and have its reads memoized by @​lahma in #​2863

Full Changelog: sebastienros/jint@v4.15.2...v4.15.3

v4.15.2

Jint 4.15.2 is a fix release.

• Async and generator suspension — loop iteration state is preserved across suspensions in async generators and for await...of (#​2852), an await suspending a right-hand side no longer stores the suspension sentinel into the target (#​2855), and suspension-node resolution unwraps correctly (#​2856).
• Correctness — calling and instanceof work on bound functions whose target is itself bound (#​2853), and inherited accessors reached through ObjectInstance.TryGetValue receive the original receiver (#​2854).
• Performance — the builtin-shape probe lane answers an authoritative miss without falling back to the slow path, which named-index misses on shaped objects were paying on every probe (#​2858); and the JsObject.Create values span is now nullable-annotated so a lazy slot's required null needs no suppression (#​2851).

What's Changed

• Annotate the layout values span so a lazy entry's null needs no suppression by @​lahma in #​2851
• Unwrap a JintStatement suspension node so for-await resumes into the right branch by @​HermanusMuellerEU in #​2856
• Fix calling and instanceof on bound functions whose target is itself bound by @​HermanusMuellerEU in #​2853
• Preserve loop iteration state across suspensions in async generators and for-await-of by @​HermanusMuellerEU in #​2852
• Pass the original receiver to inherited accessors in ObjectInstance.TryGetValue by @​HermanusMuellerEU in #​2854
• Do not store the suspension sentinel when an await suspends a right-hand side by @​HermanusMuellerEU in #​2855
• Answer an authoritative miss from the builtin-shape probe lane by @​lahma in #​2858

New Contributors

• @​HermanusMuellerEU made

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