CMake support for qt-version we are linking to

[TomZ]

The cmake variable QT_VERSION_MAJOR no longer has any value like it did in Qt5 (checked up to 641). Similar with the other 'version' variables. How do I get the Qt version in CMake?

[Christian Ehrlicher]

@TomZ said in CMake support for qt-version we are linking to:

no longer has any value like it did

It has.

find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core Sql)
find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core Sql)
message(STATUS "Qt version: ${QT_VERSION_MAJOR}.${QT_VERSION_MINOR}.${QT_VERSION_PATCH}")

-->
-- Qt version: 6.5.0

[TomZ]

Oh, wow, calling find-package twice indeed manages to populate those variables. Weird, but I'm happy it does the trick!
Thank you.

[Christian Ehrlicher]

@TomZ said in CMake support for qt-version we are linking to:

Weird, but I'm happy it does the trick!

The first find_package() already sets it.

find_package(QT NAMES Qt6 Qt5 REQUIRED COMPONENTS Core Sql)
message(STATUS "Qt version: ${QT_VERSION_MAJOR}.${QT_VERSION_MINOR}.${QT_VERSION_PATCH}")
find_package(Qt${QT_VERSION_MAJOR} REQUIRED COMPONENTS Core Sql)
message(STATUS "Qt version: ${QT_VERSION_MAJOR}.${QT_VERSION_MINOR}.${QT_VERSION_PATCH}")

-->
-- Qt version: 6.5.0
-- Qt version: 6.5.0

[TomZ]

Is there something special about the usage of NAMES with the call that fills those variables?

My usage (since my code won't compile against Qt5) was simply;
find_package(Qt6 COMPONENTS Core Quick Svg REQUIRED OPTIONAL_COMPONENTS Multimedia)

Which did not set the version variables.

So I needed to add the otherwise unneeded line find_package(QT NAMES Qt6 REQUIRED COMPONENTS Core) in order to get those variables.
I don't understand the logic why my first line doesn't generate the version variables. Not sure if I care enough if you don't know, but if you know if this is a bug or if this is just me not knowing cmake well enough, I'd be happy to learn.

Full cmake file here.

[Christian Ehrlicher]

Ok, I can see the problem. Imo they should also be set without the first call but they are not. Will take a look on it.

[Christian Ehrlicher]

I must say - those variables were also not set with Qt5. There I relied on e.g. 'Qt5Core_VERSION'

[xavierbaez]

Hello
I am trying desperately to get this working, it is not.
I am not sure what I am doing wrong.
Is there a special path or something?
For some reason, it is not detecting Qt6
I am using Manjaro

[csab6597]

running into this issue years later...
for me the line find_package(Qt6 QUIET COMPONENTS Core Gui Widgets Multimedia MultimediaWidgets) will NOT populate the version numbers, only repeating with find_package(QT NAMES Qt6) will finally do.