Date: Sat, 28 Oct 2017 12:48:51 +0200 From: Tijl Coosemans <tijl@FreeBSD.org> To: Joseph Mingrone <jrm@FreeBSD.org> Cc: ports-committers@freebsd.org, svn-ports-all@freebsd.org, svn-ports-head@freebsd.org, portmgr@FreeBSD.org Subject: Re: svn commit: r452962 - head/math/libRmath Message-ID: <20171028124843.56f8e8d3@kalimero.tijl.coosemans.org> In-Reply-To: <86d158vcve.fsf@phe.ftfl.ca> References: <201710270052.v9R0qf7A058644@repo.freebsd.org> <20171027125130.39e98c9c@kalimero.tijl.coosemans.org> <86d158vcve.fsf@phe.ftfl.ca>
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On Fri, 27 Oct 2017 12:17:41 -0300 Joseph Mingrone <jrm@FreeBSD.org> wrote: > Tijl Coosemans <tijl@FreeBSD.org> writes: >> I don't see this approach to support flang work. Will this have to be >> added to all Fortran ports? Will you modify all Fortran ports whenever >> flang supports a new architecture? Will users run into problems when >> they select gfortran in some ports and flang in others? Will you allow >> port maintainers to set different defaults in their ports? It all looks >> like high maintenance and highly error prone. Too many modifiable >> variables in too many places. >> >> USES arguments are the wrong mechanism for this in my opinion. >> DEFAULT_VERSIONS seems much better to me. Users can then add >> fortran=gfortran or fortran=flang to DEFAULT_VERSIONS. fortran.mk would >> look at FORTRAN_DEFAULT to determine the fortran compiler instead of >> fortran_ARGS. All ports would simply have USES=fortran and no options. >> That's two variables in two locations: the user's DEFAULT_VERSIONS in >> make.conf and the ports tree FORTRAN_DEFAULT in bsd.default-versions.mk >> (which could eventually be set to flang on amd64 if that turns out to be >> a better default). Advanced users that want to build some ports with >> flang and some with gfortran and think they know what they're doing can >> figure out the if-elseif-else logic needed in their make.conf. Port >> maintainers/committers should not have to deal with the support requests >> resulting from such mixed configurations which is very likely if you >> add per port options like you do in this commit. > > The DEFAULT_VERSIONS solution is cleaner, but switching all Fortran > ports to build with flang would cause breakage and, as you know, flang > is currently only available for amd64. The current, more complicated, > fine-tuned approach is less drastic. If port maintainers do not make > any changes, nothing with their port changes. They have time to test > with flang and make a choice to opt in. For example, math/R defaults to > flang (on amd64) because we have problems with gfortran [1][2] and a > work-in-progress port for Rstudio [3] only works when math/R uses flang. > Hopefully flang will mature and become supported on more architectures, > port maintainers will put in some work to support flang, and it will be > an obvious choice to move to the DEFAULT_VERSIONS approach. This is not > a precedent for choosing the compiler as a port option [4]. > > [1] https://wiki.freebsd.org/libgcc%20problem > [2] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=220359 > [3] https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=221127 > [4] E.G. cad/ghdl games/eduke32 lang/erlang-runtime16 lang/gambit-c > math/opensolaris-libm multimedia/x264 net-p2p/cpuminer net/asterisk11 > www/mod_spdy The Rstudio Makefile is missing USES=fortran. Any port that depends on a port with USES=fortran also needs USES=fortran. Even if it doesn't contain Fortran code it still needs the *FLAGS. I know that's not ideal, but adding a single word to USES is a lot better than the flang stuff added to the port (and math/R) and working on amd64 only. The download problem you have in math/R looks like the problem reported at https://lists.freebsd.org/pipermail/freebsd-current/2017-August/066855.html https://lists.freebsd.org/pipermail/freebsd-current/2017-October/067254.html and is unrelated to Fortran. So I don't think any port actually needs flang right now and nothing would break if we added flang support using DEFAULT_VERSIONS. You could then ask portmgr for an exp-run with the default set to flang to see where the problems are. Point upstream flang developers and anyone else who wants to push flang to the error logs and prioritise fixing ports that cause the biggest fallout. You'll get better results faster that way than when you expect individual port maintainers to experiment with flang or fix flang related issues.
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