Looks like not all source files get installed by ruby-2.4.1-r2.ebuild when installsources and splitdebug features are enabled. For ruby-2.3 source tree looks like this: /usr/src/debug/dev-lang/ruby-2.3.4-r2 └── ruby-2.3.4 ├── addr2line.c ├── addr2line.h ├── array.c ├── bignum.c ├── ccan │ └── list │ └── list.h ├── class.c ... └── vsnprintf.c 57 directories, 348 files For ruby-2.4 source tree looks like this: /usr/src/debug/dev-lang/ruby-2.4.1-r2 └── ruby-2.4.1 ├── include │ └── ruby │ └── ruby.h └── main.c 3 directories, 2 files mandatory emerge --info: Portage 2.3.6 (python 3.4.6-final-0, default/linux/amd64/13.0, gcc-5.4.0, glibc-2.24-r2, 4.9.33-gentoo x86_64) ================================================================= System uname: Linux-4.9.33-gentoo-x86_64-Intel-R-_Core-TM-_i7-6600U_CPU_@_2.60GHz-with-gentoo-2.4.1 KiB Mem: 32854736 total, 27273136 free KiB Swap: 33554428 total, 33554428 free Timestamp of repository gentoo: Sun, 18 Jun 2017 20:00:01 +0000 sh bash 4.4_p12 ld GNU ld (Gentoo 2.27 p1.1) 2.27 distcc 3.2rc1 x86_64-pc-linux-gnu [disabled] app-shells/bash: 4.4_p12::gentoo dev-java/java-config: 2.2.0-r3::gentoo dev-lang/perl: 5.24.1-r2::gentoo dev-lang/python: 2.7.13::gentoo, 3.4.6::gentoo dev-util/cmake: 3.8.2::gentoo dev-util/pkgconfig: 0.29.2::gentoo sys-apps/baselayout: 2.4.1::gentoo sys-apps/openrc: 0.27.2::gentoo sys-apps/sandbox: 2.10-r4::gentoo sys-devel/autoconf: 2.13::gentoo, 2.69-r3::gentoo sys-devel/automake: 1.13.4-r1::gentoo, 1.15-r2::gentoo sys-devel/binutils: 2.27-r1::gentoo, 2.28-r2::gentoo sys-devel/gcc: 5.4.0-r3::gentoo sys-devel/gcc-config: 1.8-r1::gentoo sys-devel/libtool: 2.4.6-r4::gentoo sys-devel/make: 4.2.1-r1::gentoo sys-kernel/linux-headers: 4.9::gentoo (virtual/os-headers) sys-libs/glibc: 2.24-r2::gentoo Repositories: gentoo location: /usr/portage sync-type: rsync sync-uri: rsync://rsync.gentoo.org/gentoo-portage priority: -1000 mlen location: /var/lib/mlen-overlay sync-type: git sync-uri: https://github.com/mlen/gentoo-overlay.git masters: gentoo crossdev location: /usr/local/portage-crossdev masters: gentoo priority: 10 ACCEPT_KEYWORDS="amd64 ~amd64" ACCEPT_LICENSE="* -@EULA" CBUILD="x86_64-pc-linux-gnu" CFLAGS="-march=broadwell -O2 -pipe" CHOST="x86_64-pc-linux-gnu" CONFIG_PROTECT="/etc /usr/lib64/libreoffice/program/sofficerc /usr/share/gnupg/qualified.txt" CONFIG_PROTECT_MASK="/etc/ca-certificates.conf /etc/dconf /etc/env.d /etc/fonts/fonts.conf /etc/gconf /etc/gentoo-release /etc/revdep-rebuild /etc/sandbox.d /etc/terminfo /etc/texmf/language.dat.d /etc/texmf/language.def.d /etc/texmf/updmap.d /etc/texmf/web2c" CXXFLAGS="-march=broadwell -O2 -pipe" DISTDIR="/usr/portage/distfiles" FCFLAGS="-O2 -pipe" FEATURES="assume-digests binpkg-logs cgroup config-protect-if-modified distlocks ebuild-locks fail-clean fixlafiles merge-sync news parallel-fetch preserve-libs protect-owned sandbox sfperms strict unknown-features-warn unmerge-logs unmerge-orphans userfetch userpriv usersandbox usersync xattr" FFLAGS="-O2 -pipe" GENTOO_MIRRORS="http://distfiles.gentoo.org" LANG="en_US.UTF-8" LDFLAGS="-Wl,-O1 -Wl,--as-needed" MAKEOPTS="-j5 -l5" PKGDIR="/usr/portage/packages" PORTAGE_CONFIGROOT="/" PORTAGE_RSYNC_OPTS="--recursive --links --safe-links --perms --times --omit-dir-times --compress --force --whole-file --delete --stats --human-readable --timeout=180 --exclude=/distfiles --exclude=/local --exclude=/packages --exclude=/.git" PORTAGE_TMPDIR="/var/tmp" USE="X aac aacplus acl alsa amd64 audit berkdb bzip2 caps cli consolekit cracklib crypt cryptsetup cups cxx dbus dri dri3 dvd faac flac fortran gconf gdbm geoclue geoloc geolocation gif gnome-keyring gtk gtk3 gtkstyle hidpi hotwording iconv icu idn infinality introspection iproute2 ipv6 jpeg kerberos libedit libnotify llvm lvm mmx modules mp3 mpeg multilib ncurses nls nptl offensive ogg opengl openmp opus oss pam pch pcre pm-utils png policykit pulseaudio python qt5 readline samba sdl sdl2 seccomp session sound sse sse2 ssl startup-notification tcpd theora tiff truetype udev udisks unicode unwind vaapi vim vim-syntax virt-network vorbis vpx webp widgets x264 xattr xft xinerama zlib zsh-completion" 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" 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 isync itrax mtk3301 nmea ntrip navcom oceanserver oldstyle oncore rtcm104v2 rtcm104v3 sirf skytraq superstar2 timing tsip tripmate tnt ublox ubx" INPUT_DEVICES="synaptics evdev" KERNEL="linux" L10N="en" LCD_DEVICES="bayrad cfontz cfontz633 glk hd44780 lb216 lcdm001 mtxorb ncurses text" LIBREOFFICE_EXTENSIONS="presenter-console presenter-minimizer" LINGUAS="en" OFFICE_IMPLEMENTATION="libreoffice" PHP_TARGETS="php5-6" PYTHON_SINGLE_TARGET="python3_4" PYTHON_TARGETS="python2_7 python3_4" QEMU_SOFTMMU_TARGETS="x86_64 i386 arm" QEMU_USER_TARGETS="x86_64 i386 arm" RUBY_TARGETS="ruby21 ruby23 ruby24" USERLAND="GNU" VIDEO_CARDS="intel i965" 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" Unset: CC, CPPFLAGS, CTARGET, CXX, EMERGE_DEFAULT_OPTS, INSTALL_MASK, LC_ALL, PORTAGE_BUNZIP2_COMMAND, PORTAGE_COMPRESS, PORTAGE_COMPRESS_FLAGS, PORTAGE_RSYNC_EXTRA_OPTS, USE_PYTHON
Re-assigning to the portage team since this is a feature of the package manager, not the ebuild.
