cmake: allow compilation of appman-packager when cross-compiling

cmake will not compile tools when cross-compiling anyway, but due to
our custom check, you couldn't even force the build with
-DQT_FORCE_BUILD_TOOLS=ON if you needed to.

In addition, the documentation for the "tools-only" configure option
was very outdated.

Change-Id: Ib5e6a72414ba5bbe0c5dc98d8ec5d5e66790216e
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>
(cherry picked from commit e5325d6f8bd4d3e78ce776623864f5c843dc3da3)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 37 insertions, 12 deletions

diff --git a/doc/installation.qdoc b/doc/installation.qdoc
index 91369671..8eedee58 100644
--- a/doc/installation.qdoc
+++ b/doc/installation.qdoc
@@ -142,8 +142,8 @@ modules:
       peer-to-peer D-Bus.
 \row
   \li \c{tools-only}
-  \li Set to \c yes to only build tools: \l{Controller}{appman-controller} and
-      \l{Packager}{appman-packager}.
+  \li Set to \c yes to create a build that only compiles the tools (as in \e{Qt build tools}, that
+      are only built for the host Qt when cross compiling): \l{Packager}{appman-packager}.
 \row
   \li \c{widgets-support}
   \li Set to \c yes to enable support for Qt widgets. This option can be useful to enable the use
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ad23bb40..864a5a40 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -45,8 +45,6 @@ if(NOT QT_FEATURE_am_tools_only)
     endif()
 endif()
 
-if(NOT QT_FEATURE_cross_compile OR QT_FEATURE_am_tools_only)
-    if (QT_FEATURE_am_installer)
-        add_subdirectory(tools/packager)
-    endif()
+if (QT_FEATURE_am_installer)
+    add_subdirectory(tools/packager)
 endif()
diff --git a/src/main-lib/Qt6AppManMainPrivateMacros.cmake b/src/main-lib/Qt6AppManMainPrivateMacros.cmake
index 562113a4..55d77b27 100644
--- a/src/main-lib/Qt6AppManMainPrivateMacros.cmake
+++ b/src/main-lib/Qt6AppManMainPrivateMacros.cmake
@@ -1,5 +1,36 @@
 set(_AM_MACROS_LOCATION ${CMAKE_CURRENT_LIST_DIR})
 
+function(qt_am_internal_find_host_packager)
+    if(TARGET ${QT_CMAKE_EXPORT_NAMESPACE}::appman-packager)
+        return()
+    endif()
+    if(NOT QT_HOST_PATH)
+        find_package(Qt6 COMPONENTS AppManMainPrivateTools)
+        return()
+    endif()
+    # Try to find the host version of the packager:
+    # Set up QT_HOST_PATH as an extra root path to look for the Tools package.
+    # If toolchain file already provides host paths in a predefined order, we shouldn't break it.
+    if(NOT "${QT_HOST_PATH_CMAKE_DIR}" IN_LIST CMAKE_PREFIX_PATH)
+        list(PREPEND CMAKE_PREFIX_PATH "${QT_HOST_PATH_CMAKE_DIR}")
+    endif()
+    if(NOT "${QT_HOST_PATH}" IN_LIST CMAKE_FIND_ROOT_PATH)
+        list(PREPEND CMAKE_FIND_ROOT_PATH "${QT_HOST_PATH}")
+    endif()
+    if(NOT "${QT_HOST_PATH}" IN_LIST CMAKE_PROGRAM_PATH)
+        list(PREPEND CMAKE_PROGRAM_PATH "${QT_HOST_PATH}")
+    endif()
+    # This can't use the find_package(Qt6 COMPONENTS) signature, because Qt6Config uses NO_DEFAULT
+    # and won't look at the prepend extra find root paths.
+    find_package(Qt6AppManMainPrivateTools ${PROJECT_VERSION} CONFIG
+        PATHS
+            ${_qt_additional_packages_prefix_path}
+            ${_qt_additional_packages_prefix_path_env}
+            ${QT_HOST_PATH_CMAKE_DIR}
+        NO_DEFAULT_PATH
+    )
+endfunction()
+
 function(qt_am_internal_create_copy_command file)
     if (NOT ${CMAKE_CURRENT_BINARY_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
         add_custom_command(OUTPUT ${file}
diff --git a/tests/data/CMakeLists.txt b/tests/data/CMakeLists.txt
index 6f8be60c..521749b9 100644
--- a/tests/data/CMakeLists.txt
+++ b/tests/data/CMakeLists.txt
@@ -28,6 +28,8 @@ endforeach()
 
 qt_internal_collect_command_environment(env_path env_plugin_path)
 
+qt_am_internal_find_host_packager()
+
 if (WIN32)
     find_program(bash bash.exe
                  PATHS ENV PATH
@@ -44,18 +46,12 @@ if (WIN32)
         # /mingw64/bin to $PATH, which in most cases has incompatible versions of the stdc++ and
         # gcc libs, preventing the appman-packager from starting.
 
-        if (NOT TARGET ${QT_CMAKE_EXPORT_NAMESPACE}::appman-packager)
-            find_package(Qt6 COMPONENTS AppManMainPrivateTools)
-        endif()
         add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/packages
                            COMMAND ${bash} -c 'export PATH="`cygpath -u -p \"${env_path}\"`:$$PATH" \; ${CMAKE_CURRENT_BINARY_DIR}/create-test-packages.sh $<TARGET_FILE:${QT_CMAKE_EXPORT_NAMESPACE}::appman-packager>'
                            DEPENDS ${ALL_TEST_DATA_FILES}
         )
     endif()
 else()
-    if (NOT TARGET ${QT_CMAKE_EXPORT_NAMESPACE}::appman-packager)
-        find_package(Qt6 COMPONENTS AppManMainPrivateTools)
-    endif()
     add_custom_command(OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/packages
                        COMMAND "${CMAKE_COMMAND}" -E env "PATH=${env_path}${QT_PATH_SEPARATOR}$ENV{PATH}"
                                ${CMAKE_CURRENT_BINARY_DIR}/create-test-packages.sh $<TARGET_FILE:${QT_CMAKE_EXPORT_NAMESPACE}::appman-packager>