Allow to build examples as standalone project

Create CMake config files which can be used from the very same CMake
project. These CMake config files simply do not create any targets,
controlled via the QT_NO_CREATE_TARGETS.

This patch also allows to build qtbase.git:examples as a standalone
project, against an already-built Qt.

Ran this:
  ag -s "QT " examples -l -0 | xargs -0 -n 1 .../util/cmake/pro2cmake.py --is-example

Task-number: QTBUG-74713
Change-Id: I44cce5a4048618b30f890c5b789592c227a8b47d
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>

1 files changed, 22 insertions, 19 deletions

diff --git a/src/corelib/Qt5CoreConfigExtras.cmake.in b/src/corelib/Qt5CoreConfigExtras.cmake.in
index 3775fc64b9..81d89ccd68 100644
--- a/src/corelib/Qt5CoreConfigExtras.cmake.in
+++ b/src/corelib/Qt5CoreConfigExtras.cmake.in
@@ -1,8 +1,3 @@
-set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_QT_MAJOR_VERSION @PROJECT_MAJOR_VERSION@)
-set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_QT_COORD_TYPE $$QT_COORD_TYPE)
-set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY
-  COMPATIBLE_INTERFACE_STRING QT_MAJOR_VERSION QT_COORD_TYPE
-)
 
 # include(\"${CMAKE_CURRENT_LIST_DIR}/Qt5CoreConfigExtrasMkspecDir.cmake\")
 #
@@ -14,19 +9,27 @@ set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY
 # set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${_qt5_corelib_extra_includes})
 # set(_qt5_corelib_extra_includes)
 
-# On x86 and x86-64 systems with ELF binaries (especially Linux), due to
-# a new optimization in GCC 5.x in combination with a recent version of
-# GNU binutils, compiling Qt applications with -fPIE is no longer
-# enough.
-# Applications now need to be compiled with the -fPIC option if the Qt option
-# \"reduce relocations\" is active. For backward compatibility only, Qt accepts
-# the use of -fPIE for GCC 4.x versions.
-if (CMAKE_CXX_COMPILER MATCHES "icc.*$" OR CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
-    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_OPTIONS "-fPIC")
-endif()
+if (NOT QT_NO_CREATE_TARGETS)
+    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_QT_MAJOR_VERSION @PROJECT_MAJOR_VERSION@)
+    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_QT_COORD_TYPE $$QT_COORD_TYPE)
+    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY
+      COMPATIBLE_INTERFACE_STRING QT_MAJOR_VERSION QT_COORD_TYPE
+    )
+
+    # On x86 and x86-64 systems with ELF binaries (especially Linux), due to
+    # a new optimization in GCC 5.x in combination with a recent version of
+    # GNU binutils, compiling Qt applications with -fPIE is no longer
+    # enough.
+    # Applications now need to be compiled with the -fPIC option if the Qt option
+    # \"reduce relocations\" is active. For backward compatibility only, Qt accepts
+    # the use of -fPIE for GCC 4.x versions.
+    if (CMAKE_CXX_COMPILER MATCHES "icc.*$" OR CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
+        set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_OPTIONS "-fPIC")
+    endif()
 
-if (NOT "@QT_NAMESPACE@" STREQUAL "")
-    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS QT_NAMESPACE=@QT_NAMESPACE@)
+    if (NOT "@QT_NAMESPACE@" STREQUAL "")
+        set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS QT_NAMESPACE=@QT_NAMESPACE@)
+    endif()
+    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>)
+    set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_COMPILE_FEATURES cxx_decltype)
 endif()
-set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core APPEND PROPERTY INTERFACE_COMPILE_DEFINITIONS $<$<NOT:$<CONFIG:Debug>>:QT_NO_DEBUG>)
-set_property(TARGET @QT_CMAKE_EXPORT_NAMESPACE@::Core PROPERTY INTERFACE_COMPILE_FEATURES cxx_decltype)