Assertion failure when returning incomplete property descriptor from proxy trap

[André Bargull]

SVN: rev200124
Build with: perl Tools/Scripts/build-jsc --gtk --debug


The following test case triggers this assertion error:
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ASSERTION FAILED: value
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Test case:
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Object.getOwnPropertyDescriptor(new Proxy({a:0}, { getOwnPropertyDescriptor(t,pk){return {writable:true, enumerable:true, configurable:true}} }), "")
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Stack trace:
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#0  0x00007ffff6e289ac in WTFCrash () at ../../Source/WTF/wtf/Assertions.cpp:322
#1  0x00007ffff6ceb180 in JSC::PropertyDescriptor::setDescriptor (this=0x7fffffffca50, value=..., attributes=0) at ../../Source/JavaScriptCore/runtime/PropertyDescriptor.cpp:116
#2  0x00007ffff6c62064 in JSC::JSObject::getOwnPropertyDescriptor (this=0x7fffaedbf4f0, exec=0x7fffffffcaf0, propertyName=..., descriptor=...) at ../../Source/JavaScriptCore/runtime/JSObject.cpp:2866
#3  0x00007ffff6cd385f in JSC::objectConstructorGetOwnPropertyDescriptor (exec=0x7fffffffcaf0, object=0x7fffaedbf4f0, propertyName=...) at ../../Source/JavaScriptCore/runtime/ObjectConstructor.cpp:229
#4  0x00007ffff6cd3c71 in JSC::objectConstructorGetOwnPropertyDescriptor (exec=0x7fffffffcaf0) at ../../Source/JavaScriptCore/runtime/ObjectConstructor.cpp:272
#5  0x00007fffb0bff028 in ?? ()
#6  0x00007fffffffcb60 in ?? ()
#7  0x00007ffff6a33818 in llint_entry () at ../../Source/JavaScriptCore/runtime/JSCJSValueInlines.h:1037
Backtrace stopped: frame did not save the PC
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[Radar WebKit Bug Importer]

<rdar://problem/26263841>

[Mark Lam]

I can reproduce this on a debug build.  Looking into it.

[Mark Lam]

Created attachment 281434 [details]
proposed patch.

[Mark Lam]

Thanks for the review.  Landed in r202124: <http://trac.webkit.org/r202124>.