Update JsInstanceOf to use OP_IsInst #5527
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I'm targeting at release/1.10 in hopes of getting this into node-chakracore, but can retarget to master if necessary. |
boingoing
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boingoing
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Looks fine to me. Any concerns about changing behavior of JsInstanceOf since it's shipping as a Windows API?
lib/Jsrt/Jsrt.cpp
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| *result = Js::RecyclableObject::FromVar(constructor)->HasInstance(object, scriptContext) ? true : false; | ||
| Js::Var booleanValue = Js::JavascriptOperators::OP_IsInst(object, constructor, scriptContext, nullptr); | ||
| *result = Js::JavascriptBoolean::FromVar(booleanValue)->GetValue() ? true : false; |
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A little clunky but alright. You could write this as !!Js::JavascriptBoolean::FromVar(booleanValue)->GetValue(), though I don't really like this syntax.
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I'm open to change it, I just lifted this from JsBooleanToBool later in this file.
lib/Jsrt/Jsrt.cpp
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| PARAM_NOT_NULL(result); | ||
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| *result = Js::RecyclableObject::FromVar(constructor)->HasInstance(object, scriptContext) ? true : false; | ||
| Js::Var booleanValue = Js::JavascriptOperators::OP_IsInst(object, constructor, scriptContext, nullptr); |
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I think this might not be guaranteed to return a Js::JavascriptBoolean? It looks like in the case of a callable Symbol.hasInstance that it will return the result of the function, and it is possible to define a function that doesn't return a Boolean. If I do that from script, then foo instanceof bar appears to return the truthiness of whatever I return, but I don't see that in the OP_IsInst codepath
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I think you might need to use JavascriptConversion::ToBoolean here, and then the next line should be safe.
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Ah; I misread the code in IsInst and it does in fact do the conversion there. Disregard!
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@boingoing It's a pretty subtle change in behavior and seems like a bug fix rather than a behavioral change. |
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@digitalinfinity any objections to this change landing in release/1.10? |
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Is JsInstanceOf experimental or part of the Windows API surface? If its the former, no objections. If it's the latter, I'd say this goes into master and can later make a release once the Windows Compat folks have signed off |
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It's in |
`OP_IsInst` correctly handles the ES6 `Symbol.hasInstance` property when determining whether an object is an instance of a constructor.
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@mrkmarron Is that all I need to change for TTD? |
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OP_IsInstcorrectly handles the ES6Symbol.hasInstancepropertywhen determining whether an object is an instance of a constructor.