On Friday 02 Dec 2016 09:57:14 Daniel Quinn wrote:
> Well the only difference between the output of `emerge -pv
> x11-libs/cairo` on your machine vs. mine is that you appear to be
> building 64 and 32 bit:
> 
> mine: `ABI_X86="64 -32 -x32"`
> yours: `ABI_X86="64 32 -x32"`
> 
> As for the global setting for `threads`, I have it enabled, but isn't
> that a good thing?  Should I disable threads globally?  I removed it
> from make.conf and cairo still won't build, but that's unsurprising,
> since the build makes no mention of that USE flag.
> 
> # emerge --info | grep threads
> USE="X a52 aac acl acpi aes alsa amd64 avx avx2 berkdb bluetooth
> branding bzip2 cairo cdda cdr cli colord cracklib crypt cxx dbus dri dts
> dvd dvdr eds emboss encode evo exif fam firefox flac fma3 fortran fuse
> gdbm gif glamor gnome gnome-keyring gnome-online-accounts gpm gstreamer
> gtk iconv introspection ipv6 jpeg lcms libnotify libsecret mad matroska
> mmx mmxext mng modules mp3 mp4 mpeg mtp multilib nautilus ncurses
> networkmanager nls nptl offensive ogg ogm opengl openmp pam pango pcre
> pdf png policykit popcnt ppds pulseaudio qt3support readline sdl seccomp
> session spell sqlite sse sse2 sse3 sse4_1 sse4_2 ssl ssse3
> startup-notification svg systemd tcpd theora threads tiff truetype udev
> udisks unicode upower usb v4l vaapi vdpau vim-syntax vorbis vpx x264
> x265 xattr xcb xml xpm xv xvid xvmc zlib" ABI_X86="64"
> ALSA_CARDS="ali5451 als4000 atiixp atiixp-modem bt87x ca0106 cmipci
> emu10k1x ens1370 ens1371 es1938 es1968 fm801 hda-intel intel8x0
> intel8x0m maestro3 trident usb-audio via82xx via82xx-modem ymfpci"
> APACHE2_MODULES="authn_core authz_core socache_shmcb unixd actions alias
> auth_basic authn_alias authn_anon authn_dbm authn_default authn_file
> authz_dbm authz_default authz_groupfile authz_host authz_owner
> authz_user autoindex cache cgi cgid dav dav_fs dav_lock deflate dir
> disk_cache env expires ext_filter file_cache filter headers include info
> log_config logio mem_cache mime mime_magic negotiation rewrite setenvif
> speling status unique_id userdir usertrack vhost_alias"
> CALLIGRA_FEATURES="kexi words flow plan sheets stage tables krita karbon
> braindump author" CAMERAS="ptp2" COLLECTD_PLUGINS="df interface irq load
> memory rrdtool swap syslog" CPU_FLAGS_X86="aes avx avx2 fma3 mmx mmxext
> popcnt sse sse2 sse3 sse4_1 sse4_2 ssse3" ELIBC="glibc"
> GPSD_PROTOCOLS="ashtech aivdm earthmate evermore fv18 garmin garmintxt
> gpsclock itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore
> rtcm104v2 rtcm104v3 sirf superstar2 timing tsip tripmate tnt ublox ubx"
> INPUT_DEVICES="libinput" KERNEL="linux" L10N="en-GB en"
> LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb
> ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console
> presenter-minimizer" LINGUAS="en_GB en"
> OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-6"
> PYTHON_SINGLE_TARGET="python2_7" PYTHON_TARGETS="python2_7 python3_4"
> RUBY_TARGETS="ruby20 ruby21" USERLAND="GNU" VIDEO_CARDS="nvidia"
> XTABLES_ADDONS="quota2 psd pknock lscan length2 ipv4options ipset ipp2p
> iface geoip fuzzy condition tee tarpit sysrq steal rawnat logmark ipmark
> dhcpmac delude chaos account"

euse and 'equery hasuse' show me that threads are not enabled globally on my 
machine, but boost sets IUSE="+threads" in the ebuild.

HTH.
-- 
Regards,
Mick