Bugzilla Bug 131320

The bug is reproducible and happens when trying to "emerge kde". I'm using
altivec option and ACCEPT_KEYWORD="~ppc" in my make.conf

The compiling fails only under "double" part of fftw source.
Below the output of emerge command:

 * econf: updating fftw-3.1.1-double/config.guess with
/usr/share/gnuconfig/config.guess
 * econf: updating fftw-3.1.1-double/config.sub with
/usr/share/gnuconfig/config.sub
 * econf: updating fftw-3.1.1-single/config.guess with
/usr/share/gnuconfig/config.guess
 * econf: updating fftw-3.1.1-single/config.sub with
/usr/share/gnuconfig/config.sub
./configure --prefix=/usr --host=powerpc-unknown-linux-gnu
--mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share
--sysconfdir=/etc --localstatedir=/var/lib --enable-shared --enable-threads
--enable-altivec --build=powerpc-unknown-linux-gnu
checking for a BSD-compatible install... /bin/install -c
checking whether build environment is sane... yes
checking for gawk... gawk
checking whether make sets $(MAKE)... yes
checking whether to enable maintainer-specific portions of Makefiles... no
checking build system type... powerpc-unknown-linux-gnu
checking host system type... powerpc-unknown-linux-gnu
configure: error: requested SIMD type does not match selected precision

!!! Please attach the following file when filing a report to bugs.gentoo.org:
!!! /var/tmp/portage/fftw-3.1.1/work/fftw-3.1.1-double/config.log

!!! ERROR: sci-libs/fftw-3.1.1 failed.
Call stack:
  ebuild.sh, line 1525:   Called dyn_compile
  ebuild.sh, line 928:   Called src_compile
  fftw-3.1.1.ebuild, line 62:   Called econf '--enable-shared'
'--enable-threads' '--enable-altivec'
  ebuild.sh, line 526:   Called die

And this is the emerge --info output:

Portage 2.1_pre9-r4 (default-linux/ppc/ppc32/2006.0/G4, gcc-3.4.6,
glibc-2.3.6-r3, 2.6.15-gentoo-r5 ppc)
=================================================================
System uname: 2.6.15-gentoo-r5 ppc 7450, altivec supported
Gentoo Base System version 1.12.0_pre18
dev-lang/python:     2.4.2-r1
sys-apps/sandbox:    1.2.17
sys-devel/autoconf:  2.13, 2.59-r7
sys-devel/automake:  1.4_p6, 1.5, 1.6.3, 1.7.9-r1, 1.8.5-r3, 1.9.6-r2
sys-devel/binutils:  2.16.1-r2
sys-devel/libtool:   1.5.22
virtual/os-headers:  2.6.11-r4
ACCEPT_KEYWORDS="ppc ~ppc"
AUTOCLEAN="yes"
CBUILD="powerpc-unknown-linux-gnu"
CFLAGS="-O2 -mcpu=G4 -mtune=G4 -maltivec -mabi=altivec -fno-strict-aliasing
-pipe"
CHOST="powerpc-unknown-linux-gnu"
CONFIG_PROTECT="/etc /usr/kde/2/share/config /usr/kde/3.5/env
/usr/kde/3.5/share/config /usr/kde/3.5/shutdown /usr/kde/3/share/config
/usr/share/X11/xkb /usr/share/config /var/qmail/control"
CONFIG_PROTECT_MASK="/etc/eselect/compiler /etc/gconf /etc/revdep-rebuild
/etc/terminfo /etc/env.d"
CXXFLAGS="-O2 -mcpu=G4 -mtune=G4 -maltivec -mabi=altivec -fno-strict-aliasing
-pipe"
DISTDIR="/usr/portage/distfiles"
FEATURES="autoconfig distlocks metadata-transfer sandbox sfperms strict"
GENTOO_MIRRORS="http://distfiles.gentoo.org
http://distro.ibiblio.org/pub/linux/distributions/gentoo"
PKGDIR="/usr/portage/packages"
PORTAGE_TMPDIR="/var/tmp"
PORTDIR="/usr/portage"
SYNC="rsync://rsync.gentoo.org/gentoo-portage"
USE="ppc X alsa altivec apache2 apm arts berkdb bitmap-fonts bonobo cdr cli
crypt cups dri dvd eds emboss encode esd foomaticdb fortran gdbm gif gpm
gstreamer gtk2 gtkhtml imlib ipv6 isdnlog jpeg kde ldap libg++ libwww mad
mikmod motif mozilla mp3 mpeg ncurses nls nptl ogg opengl pam pcre pdflib perl
png pppd python qt quicktime readline reflection ruby sdl session spell spl ssl
tcpd truetype truetype-fonts type1-fonts udev unicode vorbis xml xmms xorg xv
zlib elibc_glibc kernel_linux userland_GNU"
Unset:  ASFLAGS, CTARGET, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LANG, LC_ALL,
LDFLAGS, LINGUAS, MAKEOPTS, PORTDIR_OVERLAY

I noticed in double/simd/simd-altivec.h file, the following statement:

#ifndef FFTW_SINGLE
  #error "ALTIVEC only works only in single precision"
#endif

so i modified the ebuild file to force the single precision even in the
"double" case with --enable-float flag, in this way:

elif use altivec; then
   myconfdouble="$myconfdouble --enable-float"
fi

In this way the configure process doesn't fail, but I'm not sure this is the
correct way to fix the problem.

No, that fix is not correct. The correct fix is to not use altivec for double
or higher precision.

I've fixed this in the tree now.