From bc29555e6e2335e4079a9fd2f1a7e2991da87e46 Mon Sep 17 00:00:00 2001
From: Alexandru Croitor <alexandru.croitor@qt.io>
Date: Tue, 14 Jul 2020 11:25:47 +0200
Subject: [PATCH] CMake: Fix old style find_package(Qt6Foo) to work

Each module package needs to first find the Qt6 package to ensure
that all the necessary info is setup for further depedencies to be
found.

Task-number: QTBUG-81672
Change-Id: I3ee608d24c1efbb63a063261fb36341bf52fb78d
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
---
 cmake/QtModuleDependencies.cmake.in | 9 +++++++++
 cmake/QtPostProcess.cmake           | 8 +++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/cmake/QtModuleDependencies.cmake.in b/cmake/QtModuleDependencies.cmake.in
index 5d94eb9a5d3..4fdeb33c46c 100644
--- a/cmake/QtModuleDependencies.cmake.in
+++ b/cmake/QtModuleDependencies.cmake.in
@@ -1,3 +1,12 @@
+# Make sure @INSTALL_CMAKE_NAMESPACE@ is found before anything else.
+find_dependency(@INSTALL_CMAKE_NAMESPACE@ @PROJECT_VERSION@
+    PATHS "${CMAKE_CURRENT_LIST_DIR}/.." ${QT_EXAMPLES_CMAKE_PREFIX_PATH} NO_DEFAULT_PATH
+)
+if (NOT @INSTALL_CMAKE_NAMESPACE@_FOUND)
+    set(@INSTALL_CMAKE_NAMESPACE@@target@_FOUND FALSE)
+    return()
+endif()
+
 # note: _third_party_deps example: "ICU\\;1.0\\;i18n uc data;ZLIB\\;\\;"
 set(_third_party_deps "@third_party_deps@")
 
diff --git a/cmake/QtPostProcess.cmake b/cmake/QtPostProcess.cmake
index b6cbe57d410..49bb5c268d2 100644
--- a/cmake/QtPostProcess.cmake
+++ b/cmake/QtPostProcess.cmake
@@ -145,7 +145,7 @@ function(qt_internal_create_module_depends_file target)
             "${INSTALL_CMAKE_NAMESPACE}${target}Tools\;${PROJECT_VERSION}")
     endif()
 
-    # Dirty hack because https://gitlab.kitware.com/cmake/cmake/issues/19200
+    # Dirty deduplication hack because of https://gitlab.kitware.com/cmake/cmake/issues/19200
     foreach(dep ${target_deps})
         if(dep)
             list(FIND target_deps_seen "${dep}" dep_seen)
@@ -157,6 +157,12 @@ function(qt_internal_create_module_depends_file target)
                 list(GET dep 0 dep_name)
                 list(GET dep 1 dep_ver)
 
+                # Skip over Qt6 dependency, because we will manually handle it in the Dependencies
+                # file before everything else, to ensure that find_package(Qt6Core)-style works.
+                if(dep_name STREQUAL INSTALL_CMAKE_NAMESPACE)
+                    continue()
+                endif()
+
                 list(APPEND target_deps_seen "${dep_name}\;${dep_ver}")
             endif()
         endif()