Make .desktop file validation optional

CMakeLists.txt

@@ -268,10 +268,11 @@ endif(${intltool_merge_BIN} STREQUAL "intltool_merge_BIN-NOTFOUND")
 # we need desktop-file-validate to check darktable.desktop
 find_program(desktop_file_validate_BIN desktop-file-validate)
 if(${desktop_file_validate_BIN} STREQUAL "desktop_file_validate_BIN-NOTFOUND")
-  message(STATUS "Missing desktop-file-validate")
-  set(EXTERNAL_PROGRAMS_FOUND 0)
+  message(STATUS "Missing desktop-file-validate, problems in darktable.desktop might go unnoticed")
+  set(VALIDATE_DESKTOP_FILE 0)
 else(${desktop_file_validate_BIN} STREQUAL "desktop_file_validate_BIN-NOTFOUND")
   message(STATUS "Found desktop-file-validate")
+  set(VALIDATE_DESKTOP_FILE 1)
 endif(${desktop_file_validate_BIN} STREQUAL "desktop_file_validate_BIN-NOTFOUND")
 
 # we need an xslt interpreter to generate preferences_gen.h and darktablerc

data/CMakeLists.txt

@@ -55,14 +55,17 @@ add_custom_command(
 		MAIN_DEPENDENCY ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop.in
 		DEPENDS ${PO_FILES}
 )
-add_custom_target(
-  validate_darktable_desktop ALL
-  COMMAND ${desktop_file_validate_BIN} --warn-kde ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop
-  DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop
-  WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/
-  COMMENT "Checking validity of darktable.desktop"
-  )
-add_custom_target(darktable.desktop_file ALL DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop validate_darktable_desktop)
+add_custom_target(darktable.desktop_file ALL DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop)
+if(${VALIDATE_DESKTOP_FILE})
+  add_custom_target(
+    validate_darktable_desktop ALL
+    COMMAND ${desktop_file_validate_BIN} --warn-kde ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/
+    COMMENT "Checking validity of darktable.desktop"
+    )
+  add_dependencies(darktable.desktop_file validate_darktable_desktop)
+endif()
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/darktable.desktop DESTINATION ./share/applications)
 
 add_custom_command(