CMake: Properly handle CONFIG += thread aka Threads::Threads

mkspecs/features/qt.prf adds a dependency on the system threading
library if the Qt Core thread feature is enabled. Because qt.prf is
loaded by any public or internal Qt project, it's essentially a public
dependency for any Qt consumer.

To mimic that in CMake, we check if the thread feature is enabled, and
and set the Threads::Threads library as a dependency of Qt6::Platform,
which is a public target used by all Qt modules and plugins and Qt
consumers.

We also need to create a Qt6Dependencies.cmake file so we
find_package(Threads) every time find_package(Qt6) is called.

For the .prl files to be usable, we have to filter out some
CMake implementation specific directory separator tokens
'CMAKE_DIRECTORY_ID_SEP' aka '::@', which are added because we call
target_link_libraries() with a target created in a different scope
(I think).

As a result of this change, we shouldn't have to hardcode
Threads::Threads in other projects, because it's now a global public
dependency.

Task-number: QTBUG-85801
Task-number: QTBUG-85877
Change-Id: Ib5d662c43b28e63f7da49d3bd77d0ad751220b31
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Cristian Adam <cristian.adam@qt.io>

9 files changed, 0 insertions, 18 deletions

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 3642db7ee3..79da3331a8 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -6,7 +6,6 @@ if(QT_BUILD_STANDALONE_TESTS)
     # special case begin
     qt_find_package(WrapDBus1 PROVIDED_TARGETS dbus-1)
     qt_find_package(ICU COMPONENTS i18n uc data PROVIDED_TARGETS ICU::i18n ICU::uc ICU::data)
-    qt_find_package(Threads PROVIDED_TARGETS Threads::Threads)
     qt_find_package(WrapOpenSSL PROVIDED_TARGETS WrapOpenSSL::WrapOpenSSL)
     qt_find_package(WrapOpenSSLHeaders PROVIDED_TARGETS WrapOpenSSLHeaders::WrapOpenSSLHeaders)
     # special case end
diff --git a/tests/auto/corelib/kernel/qmetatype/CMakeLists.txt b/tests/auto/corelib/kernel/qmetatype/CMakeLists.txt
index 0368578c4c..a6a3bb58c1 100644
--- a/tests/auto/corelib/kernel/qmetatype/CMakeLists.txt
+++ b/tests/auto/corelib/kernel/qmetatype/CMakeLists.txt
@@ -16,7 +16,6 @@ qt_add_test(tst_qmetatype
         ../../../other/qvariant_common
     PUBLIC_LIBRARIES
         Qt::CorePrivate
-        Threads::Threads # special case
     TESTDATA ${test_data}
 )
 
diff --git a/tests/auto/corelib/thread/qpromise/CMakeLists.txt b/tests/auto/corelib/thread/qpromise/CMakeLists.txt
index c591092257..dc25a38fea 100644
--- a/tests/auto/corelib/thread/qpromise/CMakeLists.txt
+++ b/tests/auto/corelib/thread/qpromise/CMakeLists.txt
@@ -9,6 +9,4 @@ qt_add_test(tst_qpromise
         tst_qpromise.cpp
     PUBLIC_LIBRARIES
         Qt::CorePrivate
-    LIBRARIES # special case
-        Threads::Threads  # solves issue with libpthread linkage # special case
 )
diff --git a/tests/auto/corelib/thread/qthread/CMakeLists.txt b/tests/auto/corelib/thread/qthread/CMakeLists.txt
index 1038eb7210..2c92a710b3 100644
--- a/tests/auto/corelib/thread/qthread/CMakeLists.txt
+++ b/tests/auto/corelib/thread/qthread/CMakeLists.txt
@@ -10,8 +10,6 @@ qt_add_test(tst_qthread
         tst_qthread.cpp
     INCLUDE_DIRECTORIES
         ../../../../shared
-    LIBRARIES # special case
-        Threads::Threads # special case
 )
 
 ## Scopes:
diff --git a/tests/auto/corelib/thread/qthreadstorage/CMakeLists.txt b/tests/auto/corelib/thread/qthreadstorage/CMakeLists.txt
index 11ebf34799..e57f0c71ac 100644
--- a/tests/auto/corelib/thread/qthreadstorage/CMakeLists.txt
+++ b/tests/auto/corelib/thread/qthreadstorage/CMakeLists.txt
@@ -8,9 +8,6 @@
 add_qt_test(tst_qthreadstorage
     SOURCES
         tst_qthreadstorage.cpp
-    LIBRARIES # special case
-        Threads::Threads # special case
-
 )
 
 ## Scopes:
diff --git a/tests/auto/gui/kernel/qguiapplication/CMakeLists.txt b/tests/auto/gui/kernel/qguiapplication/CMakeLists.txt
index a98123aa64..d7219585a5 100644
--- a/tests/auto/gui/kernel/qguiapplication/CMakeLists.txt
+++ b/tests/auto/gui/kernel/qguiapplication/CMakeLists.txt
@@ -28,7 +28,6 @@ qt_add_test(tst_qguiapplication
     PUBLIC_LIBRARIES
         Qt::CorePrivate
         Qt::GuiPrivate
-        Threads::Threads # special case
 )
 
 # Resources:
diff --git a/tests/auto/gui/kernel/qguitimer/CMakeLists.txt b/tests/auto/gui/kernel/qguitimer/CMakeLists.txt
index 52be3ed547..8c2ec60bdf 100644
--- a/tests/auto/gui/kernel/qguitimer/CMakeLists.txt
+++ b/tests/auto/gui/kernel/qguitimer/CMakeLists.txt
@@ -10,5 +10,4 @@ qt_add_test(tst_qguitimer
     PUBLIC_LIBRARIES
         Qt::CorePrivate
         Qt::Gui
-        Threads::Threads # special case
 )
diff --git a/tests/auto/network/socket/qtcpsocket/test/CMakeLists.txt b/tests/auto/network/socket/qtcpsocket/test/CMakeLists.txt
index 3903670156..a1a6dc172a 100644
--- a/tests/auto/network/socket/qtcpsocket/test/CMakeLists.txt
+++ b/tests/auto/network/socket/qtcpsocket/test/CMakeLists.txt
@@ -21,12 +21,6 @@ qt_extend_target(tst_qtcpsocket CONDITION WIN32
         ws2_32
 )
 
-# special case begin
-set(THREADS_PREFER_PTHREAD_FLAG 1)
-find_package(Threads)
-target_link_libraries(tst_qtcpsocket PRIVATE Threads::Threads)
-# special case end
-
 #### Keys ignored in scope 4:.:.:test.pro:(CMAKE_BUILD_TYPE STREQUAL Debug):
 # DESTDIR = "../debug"
 
diff --git a/tests/benchmarks/corelib/kernel/qtimer_vs_qmetaobject/CMakeLists.txt b/tests/benchmarks/corelib/kernel/qtimer_vs_qmetaobject/CMakeLists.txt
index 4dfba51735..2619d89779 100644
--- a/tests/benchmarks/corelib/kernel/qtimer_vs_qmetaobject/CMakeLists.txt
+++ b/tests/benchmarks/corelib/kernel/qtimer_vs_qmetaobject/CMakeLists.txt
@@ -11,7 +11,6 @@ qt_add_benchmark(qtimer_vs_qmetaobject
         .
     PUBLIC_LIBRARIES
         Qt::Test
-        Threads::Threads # special case
 )
 
 #### Keys ignored in scope 1:.:.:qtimer_vs_qmetaobject.pro:<TRUE>: