Bugzilla Bug 147033

gfortran -o xfoil xfoil.o xpanel.o xoper.o xtcam.o xgdes.o xqdes.o xmdes.o
xsolv
e.o xbl.o xblsys.o xpol.o xplots.o xgeom.o xutils.o modify.o polplt.o aread.o
na
ca.o spline.o plutil.o iopol.o gui.o sort.o dplot.o profil.o userio.o
../plotlib
/libPlt.a  -L/usr/X11R6/lib -lX11 -lblas
../plotlib/libPlt.a(ps_subs.o): In function `bitpat_':
ps_subs.f:(.text+0x77): undefined reference to `rshift_'
ps_subs.f:(.text+0xee): undefined reference to `rshift_'
collect2: ld returned 1 exit status
make: *** [xfoil] Error 1

!!! ERROR: sci-physics/xfoil-6.94-r1 failed.
Call stack:
  ebuild.sh, line 1539:   Called dyn_compile
  ebuild.sh, line 939:   Called src_compile
  xfoil-6.94-r1.ebuild, line 56:   Called die

!!! failed to build xfoil
!!! If you need support, post the topmost build error, and the call stack if
rel
evant.


This is apparently the result of this gcc issue:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19292

which is a meta-bug report that shows the fortran rshift intrinsic is not yet
implemented in gfortran, the new GCC 4 fortran replacement for the older F77
compiler.

rshift is only being called twice, and it's only right-shifting by 1 each time.
It shouldn't be too hard to fix the source code to avoid the use of the
intrinsic for the time being until the gfortran compiler gets fixed. I'll have
a look at it and see if I can come up with a patch.

Created an attachment (id=96662) [details]
Patch to 6.94-r1 to fix missing rshift intrinsic

I'm no fortran expert, but I found this URL:

http://gcc.gnu.org/onlinedocs/gcc-3.4.1/g77/IShft-Intrinsic.html#IShft%20Intrinsic

which seems to exist in 4.1.1 even though it is not in the online docs yet.
This patch replaces the rshift intrinsic with this ishft intrinsic. This code
seems to compile and run OK. I tried some test cases with this new version
versus the old code compiled with gcc 3.4.6 and everything appears to work. I'm
no expert with this code though so I would hardly call it an exhaustive
analysis. 

On a related note, I notice that xfoil is now at 6.96:

http://web.mit.edu/drela/Public/web/xfoil/

I downloaded this new code and see it has the same rshift issue. Making an
ebuild for this new code will be tricky since it doesn't use autoconfig and
requires Makefile modifications for paths to binaries, compiler, etc. etc.
I'm beginning to wonder if xfoil should even be in portage. It's so specialized
I suspect few Gentoo users even know what it's for. It's a pain to configure,
and if you *really* are going to use it you probably want to run a number of
test cases to verify that the compiler-du-jour on your Gentoo box is actually
producting correct output. If none of the developers have time to stay on top
of it maybe it shouldn't even be in the portage tree.

Thank you very much for the patch :)

Created an attachment (id=118365) [details]
xfoil-6.96.ebuild

Here is an ebuild for a newer version, with some changes and a patch for the
gfortran bug. It compiles fine on my amd64, but I have no idea on how to test
the package. Let me know if it works for you.

Created an attachment (id=118366) [details]
xfoil-6.96-gfortran.patch

fixed in cvs with a few changes from the proposed patch.