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I have compiled QT5.6.2 myself with Visual Studio 2015 to compile some other software (Telegram desktop; build instructions are here https://github.com/telegramdesktop/tdesktop/blob/dev/docs/building-msvc.md#setup-gypninja-and-generate-vs-solution ).

Curiously, it seems necessary to state that I know what an unresolved external symbol is - but that I still cannot solve my issue, especially since it lies within a library that is not custom-made by me: QT

Now, when I try to compile Telegram with Visual Studio 2015 which depends on QT5.6.2, I get a weird unresolved symbol:

1>qwebpd.lib(upsampling.obj) : error LNK2019: unresolved external symbol "_WebPInitUpsamplersSSE2" in Funktion "_WebPInitUpsamplers".

I could not find anything on this function or in which library it might/should be defined.

It seems that the QT Webkit is built with Chromium and that during QT's compilation I have somehow activated some kind of SSE2 extension which, however, does not seem to be available now in Visual Studio 2015. I have also tried in "Project Settings -> C/C++ -> Code Generation" to explicitly activate SSE2 but without help. I have no clue where this function should actually be defined.

I know in general what an unresolved external symbol is, but I do not know how to resolve this error in my specific case with QT.

IceFire
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  • Possible duplicate of [What is an undefined reference/unresolved external symbol error and how do I fix it?](http://stackoverflow.com/questions/12573816/what-is-an-undefined-reference-unresolved-external-symbol-error-and-how-do-i-fix) – Jesper Juhl Apr 17 '17 at 14:44
  • This is no duplicate. I have found the solution, there was some strange behavior: At checking out QT/3rdParty/libwebp, the content of one cpp file was just removed for whatever reason; resetting to HEAD again and recompiling QT solved the problem – IceFire Apr 18 '17 at 12:03

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