8ebae84

IPC testing API is unable to reply with nullopt optional
https://bugs.webkit.org/show_bug.cgi?id=275409
rdar://129669346

Reviewed by Cameron McCormack.

Decoding std::optional would return empty JSValue (JSValue()) if the
optional was std::nullopt. This would be interpreted as a decoding
failure.

Fix this by returning the more natural value, jsUndefined value. Fix the
result array construction to not use jsUndefined to signify that the
value should be a array buffer containing the data. Use empty JSValue to
signify this. Use exception scope to detect when JS exception would
cancel the decoding as a decoding failure.

Decoding failures would use the already cleared exception as the result
JS object, causing a crash.

Fix by first constructing the JS value, then clearing the exception from
the scope.

Add decoder for WebCore::ExceptionData, to be used in testing the
message this problem was noted.

* LayoutTests/ipc/async-with-reply-optional.html: Added.
* Source/WebKit/Platform/IPC/JSIPCBinding.cpp:
(IPC::jsValueForDecodedArgumentValue):
(IPC::putJSValueForDecodedArgumentAtIndexOrArrayBufferIfUndefined): Deleted.
* Source/WebKit/Platform/IPC/JSIPCBinding.h:
(IPC::jsValueForDecodedArgumentValue):
(IPC::putJSValueForDecodeArgumentInArray):
* Source/WebKit/Shared/IPCTester.cpp:
(WebKit::IPCTester::asyncOptionalExceptionData):
* Source/WebKit/Shared/IPCTester.h:
* Source/WebKit/Shared/IPCTester.messages.in:
* Source/WebKit/WebProcess/WebPage/IPCTestingAPI.cpp:
(WebKit::IPCTestingAPI::jsSendWithAsyncReply):

Canonical link: https://commits.webkit.org/279999@main

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