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Alexandru Croitor bf315c5526 CMake: Make build system of installed Qt more relocatable
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>
2020-05-07 15:41:16 +02:00
bin CMake: Make build system of installed Qt more relocatable 2020-05-07 15:41:16 +02:00
cmake CMake: Make build system of installed Qt more relocatable 2020-05-07 15:41:16 +02:00
coin CMake: Adjust instructions for MinGW builds 2020-05-01 19:11:22 +02:00
config.tests CMake: Skip regeneration of manual compile test project 2020-04-09 11:26:46 +02:00
dist Add changes file for Qt 5.15.0 2020-04-27 20:11:04 +02:00
doc Merge remote-tracking branch 'origin/5.15' into dev 2020-04-22 15:28:01 +02:00
examples torrent example: fix premature pessimisation 2020-05-05 05:28:19 +00:00
lib Purge all fonts 2015-08-18 19:59:14 +00:00
mkspecs Merge remote-tracking branch 'origin/5.15' into dev 2020-05-05 19:51:50 +02:00
qmake Add a QRegularExpression::fromWildcard() convenience method 2020-05-06 09:57:40 +02:00
src CMake: Make build system of installed Qt more relocatable 2020-05-07 15:41:16 +02:00
tests Add more tests for QtConcurrent::filterReduced() 2020-05-07 15:23:58 +02:00
util Support special casing in configure.cmake 2020-05-05 15:34:15 +02:00
.cmake.conf pro2cmake.py: Generate .cmake.conf files for versioning 2020-04-30 17:44:03 +00:00
.gitattributes Update the git-archive export options 2012-09-07 15:39:31 +02:00
.gitignore Add .vscode in git ignore list 2020-04-22 20:38:52 -03:00
.qmake.conf Bump version 2020-02-02 13:41:14 +01:00
.tag Update the git-archive export options 2012-09-07 15:39:31 +02:00
CMakeLists.txt pro2cmake.py: Generate .cmake.conf files for versioning 2020-04-30 17:44:03 +00:00
config_help.txt Merge remote-tracking branch 'origin/5.15' into dev 2020-02-26 18:39:21 +01:00
configure Compile QRegularExpression into qmake 2020-05-05 18:41:20 +02:00
configure.bat Don't compile qmake in c++11 mode 2020-02-03 17:43:30 +01:00
configure.cmake CMake: Port the 'static_runtime' feature 2020-04-23 10:09:15 +02:00
configure.json CMake: Port the 'separate_debug_info' feature 2020-03-06 13:38:37 +01:00
configure.pri Android: Increase minimum API level to Android-23 / Android 6 2020-03-04 08:28:04 +01:00
dependencies.yaml Re-add dependencies.yaml now that qt5.git wip/qt6 builds fine 2019-09-18 13:19:31 +02:00
header.BSD Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.COMM Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.FDL Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.GPL Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.GPL-EXCEPT Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.LGPL Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.LGPL3 Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.LGPL3-COMM Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.LGPL-NOGPL2 Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.LGPL-ONLY Use placeholder for year in header.* files 2018-04-16 11:02:22 +00:00
header.MIT qsimd: add support for new x86 CPU features 2018-05-05 06:20:07 +00:00
INSTALL INSTALL: Remove outdated reference to Windows CE 2019-02-13 13:01:57 +00:00
LICENSE.FDL Initial import from the monolithic Qt. 2011-04-27 12:05:43 +02:00
LICENSE.GPL2 Add new license header templates and license files 2016-01-14 20:43:46 +00:00
LICENSE.GPL3 Add new license header templates and license files 2016-01-14 20:43:46 +00:00
LICENSE.GPL3-EXCEPT Add new license header templates and license files 2016-01-14 20:43:46 +00:00
LICENSE.LGPL3 Add new license header templates and license files 2016-01-14 20:43:46 +00:00
LICENSE.LGPLv3 Remove LICENSE.GPLv3, LICENSE.LGPLv21, LGPL_EXCEPTION.txt 2018-04-16 11:02:14 +00:00
LICENSE.QT-LICENSE-AGREEMENT Update enterprise license agreement v4.2.1 2019-12-18 13:07:19 +02:00
qtbase.pro nuke configure -host-option 2016-12-13 18:55:59 +00:00
sync.profile Move QOpenGLWidget from QtOpenGL to its own module 2020-02-18 09:22:51 +01:00