Add MdtQtPath CMake module

cmake/CMakeLists.txt

@@ -11,7 +11,7 @@ if(UNIX)
 elseif(WIN32)
   set(MDT_CMAKE_MODULES_INSTALL_DIR "cmake")
 else()
-  message(FATAL "Could not determine install dir for MdtCMakeModules")
+  message(FATAL_ERROR "Could not determine install dir for MdtCMakeModules")
 endif()
 
 # Rules to install the modules
@@ -23,6 +23,7 @@ install(
     "modules/MdtDeployUtils.cmake"
     "modules/MdtInstallCopyTargetsDependenciesScript.cmake.in"
     "modules/MdtInstallDirs.cmake"
+    "modules/MdtQtPath.cmake"
   DESTINATION "${MDT_CMAKE_MODULES_INSTALL_DIR}/modules"
   COMPONENT "${PROJECT_NAME}-cmake"
 )

cmake/modules/MdtQtPath.cmake

@@ -0,0 +1,40 @@
+#.rst:
+# MdtQtPath
+# --------------
+#
+# Get the prefix of the Qt library on which a Mdt installation depends.
+#
+# Result Variables
+# ^^^^^^^^^^^^^^^^
+#
+# Inclusion of this module defines the following variables:
+#
+# ``QT_PREFIX_PATH``
+#
+#   Path to the Qt library on which a Mdt installation depends.
+#
+
+# list(LENGTH CMAKE_PREFIX_PATH _cmake_prefix_path_length)
+# if(${_cmake_prefix_path_length} LESS 1)
+#   message(FATAL_ERROR "")
+# endif()
+
+find_file(
+  _qt_prefix_path_file
+  NAMES "QtPrefixPath.txt"
+  PATHS ${CMAKE_PREFIX_PATH}
+  NO_DEFAULT_PATH
+)
+
+if(NOT EXISTS "${_qt_prefix_path_file}")
+  message(FATAL_ERROR "Could not locate QtPrefixPath.txt. Searched in: ${CMAKE_PREFIX_PATH}")
+endif()
+
+file(STRINGS "${_qt_prefix_path_file}" QT_PREFIX_PATH)
+
+# Check that QT_PREFIX_PATH points to a Qt installation
+if(NOT QT_PREFIX_PATH)
+  message(FATAL_ERROR "QT_PREFIX_PATH was not set, please check that CMAKE_PREFIX_PATH contains a path to a Mdt installation.")
+endif()
+
+message("QT_PREFIX_PATH: ${QT_PREFIX_PATH}")