possible to adjust OPTIONS_DEFAULT based on COMPILER_TYPE?

[Don Lewis]

On 11 Mar, Mathieu Arnold wrote:
> +--On 10 mars 2015 16:30:35 -0700 Don Lewis <truckman at FreeBSD.org> wrote:
> | I've run into a situation where I'd like to change OPTIONS_DEFAULT based
> | on the value of the value of COMPILER_TYPE.  I'm setting USE_GCC=yes. If
> | the base compiler is gcc, then I can enable a particular option to make
> | the port more featureful.  If the base compiler is clang, then some of
> | the other ports the option depends on are C++ code that gets compiled
> | with clang and the port breaks because of the libstdc++ vs. libc++
> | conflict.  In that case, I'd like to disable the option to at least have
> | working binary packages available, even though they aren't as
> | featureful.
> | 
> | This doesn't look possible, though.  OPTIONS_DEFAULT needs to be set
> | before the .include <bsd.port.options.mk>, and COMPILER_TYPE isn't set
> | until after that, or possibly even after bsd.port.pre.mk.
> 
> Mmmm, yes, you're kinda stuck, I've already had a look, and it's not
> possible to have options working including port.options and also be able to
> change stuff after it.
> 
> Though, USE_GCC=yes will never use the old base gcc, but always lang/gcc
> (well, the one defined in bsd.default-versions, which if left alone is
> lang/gcc), USE_GCC=any will use gcc from base though, but I'm not sure you
> can have a good reason to use it.

At present, I always need to compile with gcc from ports, which is why I
use USE_GCC=yes.  On systems where clang is the base compiler, many
ports with C++ code will use clang as their compiler and I need to avoid
bringing in any of those because they will drag in libc++, which
conflicts with libstdc++ that we use when compiling with gcc.  One of
the options for this port (that I want to enable by default) brings in
one of those libraries, so I want to disable that option by default.

I've come up with a workaround.  Basically I'm duplicating the code from
/usr/ports/Mk/Uses/compiler.mk that sets COMPILER_TYPE and adding it to
Makefile before the OPTIONS stuff.  Portlint -a whines about the !=, but
I can live with that since this is hopefully a short term fix until I
can get the port converted to build with clang.