Use $$source_path/qtbase/cmake modules when doing non-prefix builds

This is similar to qmake, where the .prf files from the source
location of qtbase/mkspecs are used in a non-prefix build.
This means that if a developer changes the source QtBuild.cmake,
and then runs make in qtdeclarative, cmake will reconfigure
qtdeclarative because the timestamp of QtBuild.cmake changed.

Before this change you first had to make && make install in the
qtbase build directory, before qtdeclarative saw the modified
QtBuild.cmake.

This change also makes the module paths be prepended to
CMAKE_MODULE_PATH instead of appended, which means they will
take precedence to any path provided via command line.

Change-Id: I9178d5183a95b3b67bfe1b1fe91d3d3371ffe5c5
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

1 files changed, 14 insertions, 3 deletions

diff --git a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
index 1ebd321753..c7c6f757a4 100644
--- a/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
+++ b/cmake/QtBuildInternals/QtBuildInternalsConfig.cmake
@@ -13,13 +13,24 @@ if(EXISTS "${CMAKE_CURRENT_LIST_DIR}/QtBuildInternalsExtra.cmake")
 endif()
 
 macro(qt_set_up_build_internals_paths)
-    # Set up the paths for the modules.
+    # Set up the paths for the cmake modules located in the build dir. Prepend, so the paths are
+    # least important compared to the source dir ones, but more important than command line
+    # provided ones.
     set(QT_CMAKE_MODULE_PATH "${QT_BUILD_INTERNALS_PATH}/../${QT_CMAKE_EXPORT_NAMESPACE}")
-    list(APPEND CMAKE_MODULE_PATH ${QT_CMAKE_MODULE_PATH})
+    list(PREPEND CMAKE_MODULE_PATH "${QT_CMAKE_MODULE_PATH}")
+
+    # When doing a non-prefix build, prepend the qtbase source cmake directory to CMAKE_MODULE_PATH,
+    # so that if a change is done in cmake/QtBuild.cmake, it gets automatically picked up when
+    # building qtdeclarative, rather than having to build qtbase first (which will copy
+    # QtBuild.cmake to the build dir). This is similar to qmake non-prefix builds, where the
+    # source qtbase/mkspecs directory is used.
+    if(NOT QT_WILL_INSTALL)
+        list(PREPEND CMAKE_MODULE_PATH "${QT_SOURCE_TREE}/cmake")
+    endif()
 
     # If the repo has its own cmake modules, include those in the module path.
     if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
-        list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
+        list(PREPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake")
     endif()
 endmacro()