While trying to implement the 'host artifact reuse' Coin instructions
change, a bug surfaced where the qemu configurations didn't find
the host tools and instead tried to use the cross-compiled tools
while building qtbase, which failed due to not finding the
runtime linker (another unsolved issue).
Before the host artifact reuse change, the host tools were found
successfully.
The difference that caused the issue is that the target install prefix
was a direct subfolder of the host prefix.
host - /home/qt/work/qt/install
target - /home/qt/work/qt/install/target
Before the host reuse change the install prefixes were as follows
host - /home/qt/work/qt/install/host
target - /home/qt/work/qt/install/target
While looking for the Qt6CoreTools package, we temporarily set
CMAKE_FIND_ROOT_PATH and CMAKE_PREFIX_PATH to contain first
'/home/qt/work/qt/install' and then '/home/qt/work/qt/install/target'.
CMake then reroots the CMAKE_PREFIX_PATH values onto values in
CMAKE_FIND_ROOT_PATH, making an MxN list of prefixes to search.
Rerooting essentially means concatenating 2 paths, unless the
considered prefix is a subfolder of the root path.
What happened was that the first considered value was
'/home/qt/work/qt/install/home/qt/work/qt/install', a non-existent
location that gets discarded.
The second considered value was '/home/qt/work/qt/install/target.
The second value is the result of seeing that
'/home/qt/work/qt/install/target' is a subfolder of
'/home/qt/work/qt/install' and thus the root path is stripped.
All of this is done in cmFindPackageCommand::FindConfig() ->
cmFindCommon::RerootPaths.
The behavior above caused the target tools be found instead of the
host ones.
Before the host reuse change, both of the initial constructed prefixes
were discared due to them not existing, e.g.
'/home/qt/work/qt/install/target/home/qt/work/qt/install/target'
and '/home/qt/work/qt/install/host/home/qt/work/qt/install/host'
One of the later prefixes combined CMAKE_FIND_ROOT_PATH ==
'/home/qt/work/qt/install/host' + CMAKE_PREFIX_PATH == '/' resulting
in '/home/qt/work/qt/install/host/' and this accidentally found the
host tools package.
We actually stumbled upon this issue a while ago when implementing Qt
5.14 Android CMake support in 52c799ed44
That commit message mentions the fix is to add a "lib/cmake"
suffix to the PATHS option of find_package().
This would cause the subfolder => strip root behavior mentioned
above.
So finally the fix.
First, make sure not to append QT_HOST_PATH in the toolchain file,
there shouldn't be any need to do that, give that we temporarily set
it when looking for Tools packages.
Second, recreate the subdir scenario in the Qt toolchain file by
setting CMAKE_FIND_ROOT_PATH to the current (relocated) install
prefix as usual, but also setting CMAKE_PREFIX_PATH to a new value
poining to the CMake directory.
Aka '/home/alex/qt' and '/home/alex/qt/lib/cmake'.
Third, when a QT_HOST_PATH is given, save 2 paths in the generated Qt
toolchain: QT_HOST_PATH and QT_HOST_PATH_CMAKE_DIR. There are the host
equivalents of the target ones above. Use these values when looking
for host tools in Qt6CoreModuleDependencies.cmake, again facilitaing
the subdir behavior.
Note these are currently absolute paths and are not relocatable.
We'll have to figure out if it's even possible to make the host path
relocatable.
Finally as a cleanup, look for the Qt6HostInfo package in QtSetup
strictly in the given QT_HOST_PATH, so CMake doesn't accidentally find
a system Qt package.
Change-Id: Iefbcfbbcedd35f1c33417ab7e9f44eaf35ff6337
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
Three different people have encountered the issue that calling
calling qt-cmake on a project prints 1000 inclusion lines of the same
qt toolchain file, and then CMake bails out saying can't find the
CMAKE_MAKE_PROGRAM Ninja.
This happened because people accidentally called qt-cmake to configure
qtbase (instead of just cmake), which created a toolchain file that
chainloads itself recursively.
Error out when configuring qtbase, and when using the generated
toolchain file in the case when it would try to include itself.
The solution is to remove the qtbase CMakeCache.txt file, and
configure qtbase again, so it generates a proper qt.toolchain.cmake
file.
If somebody feels enthusiastic, they can move the check into the
qt-cmake and qt-cmake-private shell scripts, and error out before the
qtbase/CMakeCache.txt is polluted with the wrong toolchain file.
That is left for people that feel more comfortable with bash and batch
scripting.
Change-Id: If518c94791fe7c30731e6e462e347f26a5213c64
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
Aka handle CMAKE_INSTALL_PREFIX in a more relocatable way.
The following story inspired this change.
If a user wants to build a Qt repo into a different install prefix
than the usual Qt one, this will fail configuration because we
look for various things like syncqt, qdoc, etc relative to
CMAKE_INSTALL_PREFIX, which will now point to a different location
where none of the above tools are located.
The intent for such a use case is to support building Qt packages with
Conan, which sets a random install prefix when configuring a repo.
The idea is to derive the qt prefix dynamically from the
QtBuildInternals package location. Essentially it's a reverse relative
path from the QtBuildInternalsConfig.cmake file to the install prefix
that was specified when initially configuring qtbase.
Once the dynamic prefix is computed (so we know where the possibly
relocated Qt is), we can find tools like syncqt and qdoc.
This is an initial attempt to support a use case like that.
More design work will probably needed in case if tools / libs need to
be found in a location different than the Qt install prefix (so
support for multiple install prefixes / search paths).
An example of such a case would be when building qtdeclarative and
qtquickcontrols2 as Conan packages in one go. Most likely the
qmltyperegistrar tool will be located in the random install prefix
set by Conan, so building qtquickcontrols2 might fail due to not
finding the tool in the original Qt install prefix.
As to the implementation details, the change does the following:
- Dynamically computes and sets the
QT_BUILD_INTERNALS_RELOCATABLE_INSTALL_PREFIX variable when
find_package()'ing QtBuildInternals. It's an absolute path
pointing to where the relocated Qt is.
- When building qtbase this variable is not yet available (due
to QtBuildInternalsExtra not existing), in that case we set
the variable to the absolute path of CMAKE_INSTALL_PREFIX
(but only for the initial qtbase configuration).
- Remove QT_BUILD_INTERNALS_ORIGINAL_INSTALL_PREFIX which was used
for standalone tests purposes. It's not needed now that we compute
the location of the Qt prefix dynamically.
- The Unixy qt-cmake and qt-cmake-private shell scripts now
use a relative path to find the toolchain file we created.
- The toolchain file also dynamically computes the location of the Qt
packages, and adds them to CMAKE_PREFIX_PATH.
- A lot of existing CMAKE_INSTALL_PREFIX uses are replaced with
QT_BUILD_INTERNALS_RELOCATABLE_INSTALL_PREFIX. This includes finding
tool locations, mkspecs dir, path environment setup for tools, etc.
- Some places still use CMAKE_PREFIX_PATH in the following cases
- When determining paths while configuring qtbase (valid cases)
- When I wasn't sure what the behavior should be, so I left them
as-is (an example is documentation generation, do we want to
install it into the random Conan prefix, or into the main prefix?
Currently it installs in the random prefix).
Note that relocating a Qt installation does not work for non-prefix /
non-installed builds, due to hardcoded paths to include directories
and libraries in generated FooTargets.cmake files.
Task-number: QTBUG-83999
Change-Id: I87d6558729db93121b1715771034b03ce3295923
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
The original toolchain file may set CMAKE_FIND_ROOT_PATH instead of
appending it, which overrides the Qt's path.
Change-Id: I69a4bf4be6a999854bb8a84cf5032c6a9b739b2e
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
We need to save them in the toolchain file, otherwise we can't compile
anything :)
Change-Id: Ic5c53524fa4aa05d0b3229c2905dff92ca437ec1
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
Reviewed-by: Qt CMake Build Bot
This gets us a step into the direction of convenience that qmake
offered:
* QtBase is configured with a long command line (especially when
cross-compiling)
* Afterwards application developers (or other module builds) can
just use qmake && make
By generating a toolchain file we can capture vcpkg and toolchain
chain-loading and a shell script can take care of providing the prefix
path.
Change-Id: Ided81f5432cab862306f2bea86cfe8e56adf71b0
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>
