7+ days of dogfood
sgk at troutmask.apl.washington.edu
Wed Feb 13 03:39:37 UTC 2013
On Wed, Feb 13, 2013 at 02:15:08AM +0000, b.f. wrote:
> On 2/13/13, Steve Kargl <sgk at troutmask.apl.washington.edu> wrote:
> > On Wed, Feb 13, 2013 at 12:18:29AM +0000, b.f. wrote:
> >> ># cat /etc/make.conf|grep FFLAGS
> >> >FFLAGS = -O2 -pipe -march=native -mtune=native
> >> Please do _not_ assign flags unconditionally in make.conf.
> > FFLAGS is for compiling Fortran. I'm one of the people who
> > has spent years working/patching gfortran. I think I might
> > have a better understanding of what options to use with
> > gfortran than most people.
> I know you have, but you are giving advice that is liable to be abused
> by those who are less experienced. The flags you are adding are not
> the problem -- it's the way that you are adding them -- specifically,
> the assignment in the first line of your snippet, if it's applied
> unconditionally. You should either be appending all of them, or
> assigning them conditionally, so that they are sure to be assigned
> only once, or -- preferably -- using another makefile that can't be
> re-read multiple times during a build (ports/Mk/bsd.port.mk
> automatically includes several makefiles that can be used for this
> purpose, if you are building a port). You have been lucky not to trip
> over this: every couple of months for the last several years I have
> had to debug errors reported by users that arise from this problem. It
> is more common with CFLAGS and CXXFLAGS but it can happen with FFLAGS,
Try 'find /usr/ports -name Makefile -maxdepth 3 | xargs grep FFLAGS'
Then go read about the options chosen by the various port maintainers.
I specifically set FFLAGS to avoid the questionable options set in
the ports. If -malign-double appears in a port, it should probably
be marked as broken. If a port uses -fdefault-real-8, it should probably
be marked as broken. If a port uses -ffast-math, it may have issues that
are extremely difficult to debug.
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