[Interest] Qt/Mac and "Application Extensions Only"

[René J.V. Bertin]

Hi,

Building Qt 5.9.3 I caught a couple of linker warnings about it being unsafe to use dylib with application extensions. Figuring out the source of that I found a remark that "Qt libraries have to use only APIs that are safe to use for application extensions". This despite the fact that I'm not getting a build that's App Store compatible (which I wouldn't want anyway).

Is there a post somewhere about why Qt libraries have to be built that way and what it implies in practice (if you just want to be able to build and run cross-platform FOSS software including KDE/KF5)?

I see the `CONFIG += app_extension_api_only` line appearing in a number of mkspecs/*.prf files which suggests that the setting *might* be applied to user projects too (like when building a Qt plugin).

Is there any risk to commenting those lines out before building Qt, following the principle of "don't use compiler options that you do not understand fully and/or do not really need"?

Thanks,
R.