Update explainer on stack trace support in JS API #197
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This updates the explainer on - We add stack trace option to `Exception` class in the JS API - `Exception` can contain an optional `externref` to carry a stack trace - `Exception` is not a subclass of JS `Error` The WebIDL syntax is suggested by @eqrion in WebAssembly#183 (comment) and WebAssembly#183 (comment). Addresses WebAssembly#183 and WebAssembly#189.
aheejin
requested review from
takikawa,
Ms2ger,
dschuff,
thibaudmichaud,
kmiller68 and
rossberg
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@eqrion Thanks for the suggestion! It looks I can't add you to reviewers, so cc'ing you here. |
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Thank you, this looks good to me! |
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Gentle ping :) |
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@Ms2ger I have a request :) Can you let me merge my own PRs going forward? Especially when there are multiple reviewers, sometimes I'd like to wait a little more. I also generally prefer letting authors merge PRs themselves in case they have the right access to the repo, which is what we do in our wasm toolchain repos (emscripten and binaryen) |
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Apologies, I'll try to remember that |
| To preserve stack trace info when crossing the JS to Wasm boundary, `Exception` | ||
| can internally contain an optional `externref` value containing a stack trace | ||
| string, which is propagated when caught by `catch` and rethrown by `rethrow`. |
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Hm, is this normative text or is it just an implementation note? IIUC, "internally" means that the reference is not observable in Wasm. Does it even matter then whether it is an externref?
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I suspect it is less error-prone to acknowledge the extra data that needs to be preserved in the core spec, rather than monkey-patching it from the outside. I'm not sure if that means we need to spell out that it's an externref, though.
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@Ms2ger, I'm not sure how we could do that without actually devolving into spec'ing how JS stack traces work – presumably, the trace also needs to be extended in certain situations. Giving the handwavy-ness of stack traces in JS itself, we can only get that wrong. I'd rather not go there.
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@rossberg Do you not prefer taking the optional stack trace on/off option in WebAssembly.Exception constructor, or you are OK with that part but doesn't want to say anything about how it is achieved and we delegate that entirely to toolchains?
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@aheejin, the latter. Or at least I would keep the "how" slightly more abstract.
| To preserve stack trace info when crossing the JS to Wasm boundary, `Exception` | |
| can internally contain an optional `externref` value containing a stack trace | |
| string, which is propagated when caught by `catch` and rethrown by `rethrow`. | |
| To preserve stack trace info when crossing the JS to Wasm boundary, exceptions | |
| can internally contain a stack trace, which is propagated when caught by `catch` and rethrown by `rethrow`. |
This was suggested by @rossberg in WebAssembly#197 (comment).
This was suggested by @rossberg in #197 (comment).
This updates the explainer on
Exceptionclass in the JS APIExceptioncan contain an optionalexternrefto carry a stack traceExceptionis not a subclass of JSErrorThe WebIDL syntax is suggested by @eqrion in
#183 (comment)
and
#183 (comment).
Addresses #183 and #189.