[mrousavy]

Summary

RuntimeDecorator doesn't forward createValueFromJsonUtf8 to the plain runtime, so decorated runtimes use the JSON.parse-based default from jsi.cpp instead of the plain runtime's parser. For Hermes that means makeThreadSafeHermesRuntime and anything built on WithRuntimeDecorator never reach the native parser from a3f615c.

I think this was missed rather than chosen. WithRuntimeDecorator already overrides it (added in c2a0da2 as Around plus RD::createValueFromJsonUtf8), which only makes sense if RuntimeDecorator forwards it. Today that RD:: call lands in the default, so it takes one Around plus several nested ones for global, getProperty, createStringFromUtf8 and call. It's also observable: on a thread-safe runtime, after JSON.parse = () => 'hijacked', Value::createFromJsonUtf8 returns 'hijacked', and after delete globalThis.JSON it throws. A plain HermesRuntime parses normally in both cases.

TracingRuntime relies on the current behavior. JSON parsing only shows up in traces because the default splits into traced global/getProperty/call calls. Forwarding alone would hand back a value from the plain runtime with no def, and replay would hit the "has no def" assert in useObjectID. So TracingRuntime now overrides createValueFromJsonUtf8 and calls jsi::Runtime::createValueFromJsonUtf8 explicitly. That runs the same code as before, so traces are unchanged and there's no new record type. If you'd prefer a dedicated SynthTrace record I can do that instead.

A side effect: decorators that watched JSON parsing through global/getProperty/call now need to override createValueFromJsonUtf8, like every other forwarded method. For example, TimedRuntime no longer counts JSON parsing under its call timer. The other methods decorators don't forward yet are the createError* family (#2203) and String::length (#2205). React Native's decorator.h has the same gap.

Test Plan

New tests:

• JSITest.CreateValueFromJsonUtf8Test checks that parsing through a RuntimeDecorator reaches the wrapped runtime, and keeps coverage of the jsi.cpp default through a decorator that overrides back to it. It calls outer.createValueFromJsonUtf8 directly to check that the override remains public.
• HermesRuntimeTest.CreateValueFromJsonUtf8IgnoresGlobalJSON replaces JSON.parse and checks that parsing still works, on the plain and thread-safe runtimes.
• SynthTraceReplayTest.CreateValueFromJsonUtf8Replay parses on the tracing runtime, uses the result from native code, and replays with verification.

Without the change the first two fail (the second only on the thread-safe runtime). With only the decorator.h part, the SynthTrace test aborts in useObjectID. With the full change all pass, and so does the full APITests binary (360 tests) in a Debug + ASan build. APILeanTests also passes.

The direct call fails to compile with the previous header because createValueFromJsonUtf8 is protected. With this revision, cmake --build cmake-build-asan --target check-hermes -j 12 passes in Debug + ASan: 4,126 expected passes, 6 expected failures, and 197 unsupported tests. Node-API checks: 41 passes and 23 skips.

[meta-codesync]

@lavenzg has imported this pull request. If you are a Meta employee, you can view this in D124177263.

[meta-codesync]

@lavenzg merged this pull request in 1d2fc48.