[qt-build] How to differentiate host and target in source code/qmake?

[myobyte]

How to differentiate host and target in source code/qmake?

Both my host and target is linux-gcc, but with different versions.

I would like to add some compiler/linker flags for target.
For example, in order to use santizer, I have to add cc flags, and linker flags [to a proper place].

However host toolchain version is different, which means that if I casually do something like this:
https://codereview.qt-project.org/#change,43420
Host tools build fails with unknown options.

There are several problems here:

1. I couldn't find a way to add target-only stuffs to qmake.
2. I couldn't find a way to add linker flags to the designated place. (which is critical)
   qmake bootstrap process is tricky and surprising, and linker flags are ordered as a side effect of this process.

In case of a native build, these problems is relatively easy to workaround.
However for a cross build, these problems become nasty.

[myobyte]

host_build {
}
Can be used, and is available quite early. (maybe around spec_pre.prf)

[J.Hilk]

@myobyte
hi,

take a look at the qmake variables especially the subsection QMAKE_HOST it will allow you to specify the host:

.arch	Host architecture
.os	Host OS
.cpu_count	Number of available cpus
.name	Host computer name
.version	Host OS version number
.version_string	Host OS version string

example from the docu:

win32-g++:contains(QMAKE_HOST.arch, x86_64):{
    message("Host is 64bit")
    ...
}

[myobyte]

@J.Hilk said in [qt-build] How to differentiate host and target in source code/qmake?:

@myobyte
hi,

take a look at the qmake variables especially the subsection QMAKE_HOST it will allow you to specify the host:

I can't see how QMAKE_HOST can be used to add target-only flags in qmake.

[SGaist]

Hi,

Something's not clear here, do you mean that your are "cross-compiling" for the same architecture but with a different version of the compiler ?

[myobyte]

@SGaist said in [qt-build] How to differentiate host and target in source code/qmake?:

Hi,

Something's not clear here, do you mean that your are "cross-compiling" for the same architecture but with a different version of the compiler ?

I use both native build and cross build.
The cross-compiling build is target=arm/arm64, while host=x86_x64.
The native build is x86_64.

Besides, the cc/ld options is not something that could be put into platform conf and forget.
As far as I can recall, platform conf is loaded very early, and cc/ld options will appear at the begin of the gcc cmdline -- the wrong place that build will fail.

[SGaist]

Then you should use a scope matching your target. e.g. linux-beagleboard-g++ if you are using the BBB mkspec

linux-beagleboard-g++ {
message("BBB specifics")
}

[myobyte]

host_build {
}
Can be used, and is available quite early. (maybe around spec_pre.prf)