Hi, we are running into problems when using add_custom_command() without inputs. The semantics of this is documented as "If DEPENDS is not specified the command will run whenever the OUTPUT is missing", which is exactly what we need. This is working everywhere, but not (cleanly) with VisualStudio generators, which introduce the rule file.
The documented behavior is violated if the custom command's output existed before the CMake generator runs. VisualStudio will then always trigger the command, as its input (the rule file) is newer than the outputs. Unfortunately, some of our generators notice that the output does not change and does not touch the output timestamp. This prevents dependent targets from rebuilding, but the generators will be triggered, which is time-consuming. We can think of a number of workarounds for this, but I wanted to see whether there is general agreement that the behavior between non-VS and the VS generators should be identical and according to documentation. A fix in the CMake code could force "old" rule files, which then would never trigger the command on their own. Please let me know, what you think, Mike -- Powered by www.kitware.com Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Kitware offers various services to support the CMake community. For more information on each offering, please visit: CMake Support: http://cmake.org/cmake/help/support.html CMake Consulting: http://cmake.org/cmake/help/consulting.html CMake Training Courses: http://cmake.org/cmake/help/training.html Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Follow this link to subscribe/unsubscribe: http://public.kitware.com/mailman/listinfo/cmake-developers
