William Stein wrote: > On Sun, Nov 22, 2009 at 5:41 AM, Dr. David Kirkby > <david.kir...@onetel.net> wrote: >> In a recentish update to the prereq script (from 0.3 0.4) >> >> http://trac.sagemath.org/sage_trac/ticket/7021 >> >> I added a check on gcc version. The following happens. >> >> 1) gcc 4.0.0 exits, saying its buggy. >> 2) gcc >= 4.0.1, runs ok >> 3) gcc < 4.3, saying its too old. >> 4) 4.3.x, issues a warning, but allows to continue. >> >> >> I've just run it on my Ultra 27, and without changing the compilers, it uses >> the >> default gcc (a 3.4.x), and so I got to case 4. >> >> The warning is as clear as I could make it. >> >> checking gcc version... 3.4.3 >> checking if g++ accepts -dumpversion option... yes >> checking g++ version... 3.4.3 >> configure: Good, gcc and g++ are the same version (3.4.3) >> configure: Later, it will be checked if GCC 3.4.3 is suitable >> configure: WARNING: ****************************************************** >> configure: WARNING: ****************************************************** >> configure: WARNING: ****************************************************** >> configure: WARNING: GCC 3.4.3 is too old and can not build Sage. >> configure: WARNING: Please use a gcc of at least 4.0.1 >> configure: WARNING: if you just want Sage to build without problems. >> configure: WARNING: >> configure: WARNING: However, rather than exit as this point, the Sage >> configure: WARNING: build will continue, in case you want to debug >> configure: WARNING: a package, that will not build without a later GCC, >> configure: WARNING: but you want to try getting it to work with >> configure: WARNING: GCC 3.4.3. At the time of writing, (28th Sept 2009) >> configure: WARNING: 'ratpoints' was a program, needing GCC 4.0.1 >> configure: WARNING: which is later than would be ideal. >> configure: WARNING: ****************************************************** >> configure: WARNING: ****************************************************** >> configure: WARNING: ****************************************************** >> >> >> That is pretty clear, but it flies past so quick on my Ultra 27 that I think >> it >> could easily be missed. I'm wondering if we should exit if gcc < 4.0.1, and >> only >> allow gcc 4.3.x versions to continue if some environment variable is set. >> >> So it instead issues a message telling someone to set the environment >> variable >> >> SAGE_LET_ME_USE_OLD_GCC to "yes" if they wish to use a gcc 4.3.x. >> > > Can we reuse and existing environment variable? E.g,. SAGE_PORT="yes" > allows you to do anything. > > William >
No, since to build on Solaris x86, (on any other unsupported platform), one already needs to have SAGE_PORT set to something non-empty. Since I was building on Solaris x86, I'd already needed to set SAGE_PORT. But on a fast x86 box, the warning about an old gcc will not be seen. I did consider insisting SAGE_PORT was set to something specific, like "SAGE_PORT=permit_old_gcc", but the fact SAGE_PORT is then non-empty, would mean a ton of other checks would not be performed, or would at least need complicated re-writes. I know its not a good idea to add endless environment variables, but in this case, we do not even need to bother documenting SAGE_LET_ME_USE_OLD_GCC, as the configure script would essentially be self-documenting. I'd suggest something like: configure: WARNING: GCC 3.4.3 is too old and can not build Sage. configure: WARNING: Please use a gcc of at least 4.0.1 configure: WARNING: if you just want Sage to build without problems. configure: WARNING: configure: WARNING: If you insist on using a gcc which is known to configure: WARNING: fail to build Sage, then set the configure: WARNING: environment variable PERMIT_OLD_GCC to "yes". configure: WARNING: configure: WARNING: The only reason to do this, would be if you want to configure: WARNING: make changes to Sage which allow it to build configure: WARNING: with older versions of gcc. configure: WARNING: configure: ERROR: Exiting, as gcc is too old. (I think 'PERMIT_OLD_GCC' or 'SAGE_PERMIT_OLD_GCC', is better than 'SAGE_LET_ME_USE_OLD_GCC'). From a practical point of view, is anyone actually going to try to get Sage working with gcc 3.4.x? If not, simply exiting with no option to override it might be acceptable, though I would personally prefer to give someone the option of overriding if they want to try. I thought at one point it would be advantageous to get Sage building with 3.4.3 on Solaris, as it would allow Sage to be built with the Sun supplied compiler. But then I realised that the compiler supplied by Sun does not support Fortran, so it will never build Sage anyway. So even on Solaris, one *must* install gcc 4.0.1 or later with Fortran support. Whatever we do, I do not believe the current situation is satisfactory. With computers getting faster and faster, warnings like this will have even less chance of being seen. On Solaris, it has a fairly high probability of being generated too, as the only compiler supplied is too old. On a related point, on Solaris one *must* install a GCC with Fortran support, as the sage_fortran binary in Sage has no compiler for Solaris. In which case, perhaps we should consider exiting on Solaris, AIX, HP-UX, IRIX and Tru64 unless there is a Fortran compiler. (i.e. if gcc is used, we check it supports Fortran). I'm not sure what binaries that does contain (Linux and OS X perhaps??). Dave -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
