[CMake] Visual Studio 2010 generator and custom command

[Campbell Barton]

On Wed, Sep 29, 2010 at 10:02 AM, elizabeta petreska
<elizabeta.petreska at gmail.com> wrote:
> Hi,
>
> I asked this question some time ago in the mailing list. Unfortunately, I
> did not try to resolve this issue since then, so I am trying again. :)
>
> I am using Visual Studio 2010 generator and cmake 2.8.2.
>
> Why the following custom command is runing all the time, although the input
> dependency ( myfile.txt ) is not changed ? With Visual Studio 2005 it is
> working ok.
>
> CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
> PROJECT(quick_test)
>
> ADD_CUSTOM_COMMAND(
>  OUTPUT "${PROJECT_BINARY_DIR}/$(ConfigurationName)/generated.txt"
>  COMMAND ${CMAKE_COMMAND} -E copy
>   "${PROJECT_SOURCE_DIR}/myfile.txt"
>   "${PROJECT_BINARY_DIR}/$(ConfigurationName)/generated.txt"
>  DEPENDS "${PROJECT_SOURCE_DIR}/myfile.txt"
>  )
> ADD_CUSTOM_TARGET(${PROJECT_NAME} DEPENDS
> "${PROJECT_BINARY_DIR}/$(ConfigurationName)/generated.txt")

Was just about to mail this list with the same problem, but using
Makefiles on linux so its probably not build system spesific.
Basically the command to generate always runs even if the inputs are
older then the outputs.

The only work around I can think of is to write a cmake script which
is called rather then the generator directly, this cmake script can do
the file comparisons to work out if generating the files is really
needed, but would prefer if this wasnt needed.