[CMake] How to force package target generate a file before proceeding

[Shyrokov, Sasha]

Hi,

I would like to include a generated file into a package. I have something like that:
include(CPack)

add_custom_command (OUTPUT hgHash.txt
    COMMAND hg --debug id -i >hgHash.txt
    COMMENT "Getting hg hash")

add_custom_target (hg_hash
    DEPENDS hgHash.txt
    COMMENT "hg_hash target")

Now the following would solve my problems, but it does not work:
add_dependencies(package hg_hash)

I get:
Cannot add target-level dependencies to non-existent target "package".

I know I have CPack configured properly, because if I create the file manually it gets included. I also can add the dependency on one of my libraries, but I only want to generate this file when package is executed.

What am I missing?

Thanks,
Sasha