Setting up a .pro file that works for wasm_singlethread and wasm_multithread

Matthew Daskilewicz

I'm trying to set up a .pro file that works for both wasm_singlethread and wasm_multithread. But right now it fails on "Qt += concurrent" when using wasm_singlthread, since that module is not available. How can I do this? E.g. is there a separate scope that distinguishes wasm single vs multi? Or a scope block that would otherwise explicitly check if the concurrent module is available?

Thanks

SimonSchroeder

QtConcurrent relies on multiple threads. It cannot work with wasm_singlethread. If you want single-threaded code, you need to write single threaded code.

Matthew Daskilewicz

Yes, i know. The question is how to set up a project file for qmake so that it will only run the line "Qt += concurrent" if the concurrent module exists.

SimonSchroeder

Now I understand a little better what you are asking. I am not sure if there is such a thing as querying if a module exists. I'm also not using wasm and don't know if you can actually distinguish between singlethreaded and multithreaded.

Here is the easiest workaround that comes to mind: Create a CONFIG variable like singlethreaded. Then you can check for it:

CONFIG(singlethreaded): {
}
else: {
  QT += concurrent
}

On the "command line" you just add qmake CONFIG+=singlethreaded ... to your call to qmake. In QtCreator under "Projects" for the wasm_singlethreaded kit you just add CONFIG+=singlethreaded as "Additional arguments" under the qmake build step.