Re: [Doxygen-users] Compare with already existing and identical output file and *not* refresh its *filesystem* timestamp?

[Marc H. <mar...@gm...>]

> Short of actually implementing complex incremental builds, there's
> another, unrelated and also much simpler optimization Doxygen could do:
> just vaguely keep track of modified times on *input* files.
> [..]
> This would make a huge difference for incremental builds that involve not
> just doxygen but other (and faster) tools too; they could just skip running
> doxygen when not needed.
>
> PS: If anyone has ideas on how to emulate this with a small number of
> lines of CMake then please share. For instance this could generate an empty
> file right before starting doxygen as a decent approximation.
>
>
OK, emulating this in CMake was much easier than I thought. It would still
be simpler and safer if Doxygen provided it for any build system...

set(DOXYGEN_RUN_STAMP build/doxygen_run_tstamp)

# Duplicates Doxyfile, must be kept in sync manually
file(GLOB_RECURSE .  DOXYGEN_SOURCES
../include/*.[c,h]
../tests/*.[c,h]
 ...
)

add_custom_command(
   OUTPUT ${DOXYGEN_RUN_STAMP}
   COMMAND cmake -E touch ${DOXYGEN_RUN_STAMP}
   COMMAND doxygen ...
   ...
   DEPENDS ${DOXYGEN_SOURCES}
)