[Development] QtWebEngine: multiple toolchains needed?

[Elad Lahav]

Hello,

I am trying to build QtWebEngine for QNX. As both Qt 6.4.2 and the
Blink engine work independently on the platform I was hoping this
would be feasible.
The biggest problem I ran into so far is that there seem to be
multiple toolchains involved in the build. It starts with the QNX
toolchain I added, but then at some point fails because llvm-build, a
directory that holds pre-built clang tools, is not available. This
directory does exist when building parts of Chromium for QNX.
Comparing with the Linux build I noticed that it has a separate
"host_toolchain" directory that points back to GCC. I can mimic that,
but it is really not clear to me why there are multiple toolchains
involved in this build.
If these are needed, is the extra toolchain supposed to be building
for the host or for the target? Note that I am currently building on
Linux, as porting the whole build infrastructure to QNX (Ninja wrapped
in GN wrapped in CMake) is not something I want to deal with right
now...

Any thoughts?

Thanks,
--Elad