proper DOXYGEN option default value

[Steve Wills]

On Wed, Mar 04, 2015 at 02:41:48PM -0800, Don Lewis wrote:
> I maintain a number of ports that use doxygen to generate their
> documentation.  They all list DOXYGEN in OPTIONS_DEFAULT so that
> the packages will include documentation.
> 
> I recently received a PR for one of those ports that mentioned that most
> users don't require the documentation and pointed out that anyone
> building the port will find it is very painful because of the amount of
> time it takes to build doxygen and all of its dependencies (primarily
> all the TeX stuff).
> 
> It's been my experience that there is enough churn in the dependencies
> that the whole mess needs to get rebuilt fairly frequently.
> 
> As I see it, the pros and cons of listing DOXYGEN in OPTIONS_DEFAULT
> are:
>   Pros:
>     * Users who need the documentation can use the binary packages if
>       they desire
>     * This option gets regular exercise on the build cluster
>   Cons:
>       * A bit of extra load on the ports build cluster to install
>         doxygen and its dependencies as a BUILD_DEPENDS for each
>         supported OS version and architecture
>       * The packages are a bit larger
>       * A bit more space is consumed on the user's machine because
>         documentation is installed, even if they don't need it
>       * Users building from ports have to build and install doxygen
>         and it's dependencies unless they take measures to avoid it,
>         either by disabling the option for each port or adding
>         OPTIONS_UNSET=DOXYGEN to their /etc/make.conf to do this
>         globally
> 
> The pros and cons of removing DOXYGEN from OPTIONS_DEFAULT:
>   Pros:
>      * Less load on the ports build cluster
>      * Smaller packages
>      * Less space consumed on most user machines
>      * Users building from ports who do not need the documentation don't
>        pay the doxygen penalty without taking any special measures
>   Cons:
>      * Anyone who does need the documentation has to build from the
>        port and pay the cost of building and installing doxygen and its
>        dependencies.
>      * The DOXYGEN option would not get regular testing and could be
>        subject to bit rot.
> 
> Ideally, the documentation could be built and packaged separately.  It
> could even be NO_ARCH.   Unfortunately, at this time this would require
> adding a bunch of new ports just for the documentation.
> 
> Since these ports only generate HTML documentation, it might be helpful
> to have a doxygen-lite port that has GRAPHVIZ and LATEX disabled, and
> use that as a BUILD_DEPENDS.  That introduces the problem of conflicts
> between doxygen and doxygen-lite if someone who builds from ports needs
> the full featured doxygen for other purposes.
> 
> Since we have neither of the above, should I leave my ports as-is, or
> should I disable DOXYGEN by default?

Personally I would tend to lean towards leaving DOXYGEN off by default,
especially if there is other accompanying documentation. This is the case for
lang/ruby* for example.

But beward that this may mean it is more likely that the DOXYGEN parts of the
plist may become outdated when the doxygen port is updated. So keep testing
that option.

Steve