I was playing with the unsupported (is it still?) -flto CFLAG and saw a lot of compilation breakages. It seems that there is a very easy fix for many of them. It is enough to put the plugin build by gcc in a place, where ld sees it by: mkdir -p /usr/x86_64-pc-linux-gnu/binutils-bin/lib/bfd-plugins ln -s /usr/libexec/gcc/x86_64-pc-linux-gnu/4.9.2/liblto_plugin.so /usr/x86_64-pc-linux-gnu/binutils-bin/lib/bfd-plugins/ I'll demonstrate the problem on gzip package. More details e.g.: http://marxin.github.io/posts/gentoo-linux-packages-with-gcc-4-dot-9-lto I have sys-devel/binutils-2.25 and it is fine. Reproducible: Always Steps to Reproduce: 1. place -flto in CFLAGS and LDFLAGS in /etc/portage/make.conf 2. emerge --oneshot gzip Actual Results: .... CC glthread/lock.o AR libgzip.a BFD: c-ctype.o: plugin needed to handle lto object BFD: c-strcasecmp.o: plugin needed to handle lto object BFD: c-strncasecmp.o: plugin needed to handle lto object BFD: cloexec.o: plugin needed to handle lto object BFD: close-stream.o: plugin needed to handle lto object BFD: closein.o: plugin needed to handle lto object BFD: closeout.o: plugin needed to handle lto object BFD: opendir-safer.o: plugin needed to handle lto object BFD: dirname-lgpl.o: plugin needed to handle lto object BFD: basename-lgpl.o: plugin needed to handle lto object BFD: stripslash.o: plugin needed to handle lto object BFD: exitfail.o: plugin needed to handle lto object BFD: creat-safer.o: plugin needed to handle lto object BFD: open-safer.o: plugin needed to handle lto object BFD: fd-hook.o: plugin needed to handle lto object BFD: filenamecat-lgpl.o: plugin needed to handle lto object BFD: freading.o: plugin needed to handle lto object BFD: gettime.o: plugin needed to handle lto object BFD: localcharset.o: plugin needed to handle lto object BFD: glthread/lock.o: plugin needed to handle lto object BFD: math.o: plugin needed to handle lto object BFD: openat-die.o: plugin needed to handle lto object BFD: printf-frexp.o: plugin needed to handle lto object BFD: printf-frexpl.o: plugin needed to handle lto object BFD: quotearg.o: plugin needed to handle lto object BFD: save-cwd.o: plugin needed to handle lto object BFD: savedir.o: plugin needed to handle lto object BFD: stat-time.o: plugin needed to handle lto object BFD: glthread/threadlib.o: plugin needed to handle lto object BFD: timespec.o: plugin needed to handle lto object BFD: unistd.o: plugin needed to handle lto object BFD: dup-safer.o: plugin needed to handle lto object BFD: fd-safer.o: plugin needed to handle lto object BFD: pipe-safer.o: plugin needed to handle lto object BFD: utimens.o: plugin needed to handle lto object BFD: wctype-h.o: plugin needed to handle lto object BFD: xmalloc.o: plugin needed to handle lto object ..... GEN zmore GEN znew AR libver.a BFD: version.o: plugin needed to handle lto object BFD: version.o: plugin needed to handle lto object CCLD gzip /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `progerror.lto_priv.43': ccj4A3N3.ltrans0.o:(.text+0x28): undefined reference to `rpl_fprintf' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `license': ccj4A3N3.ltrans0.o:(.text+0x5a): undefined reference to `Version' ccj4A3N3.ltrans0.o:(.text+0x6c): undefined reference to `_rpl_printf' ccj4A3N3.ltrans0.o:(.text+0x81): undefined reference to `_rpl_printf' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `version': ccj4A3N3.ltrans0.o:(.text+0xa1): undefined reference to `_rpl_printf' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `help': ccj4A3N3.ltrans0.o:(.text+0xd5): undefined reference to `_rpl_printf' ccj4A3N3.ltrans0.o:(.text+0xea): undefined reference to `_rpl_printf' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `try_help': ccj4A3N3.ltrans0.o:(.text+0x53a): undefined reference to `rpl_fprintf' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `treat_stdin': ccj4A3N3.ltrans0.o:(.text+0x617): undefined reference to `rpl_fprintf' ccj4A3N3.ltrans0.o:(.text+0x6eb): undefined reference to `get_stat_mtime' ccj4A3N3.ltrans0.o:(.text+0x725): undefined reference to `gettime' /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans0.ltrans.o: In function `treat_file.lto_priv.42': ccj4A3N3.ltrans0.o:(.text+0x93c): undefined reference to `rpl_fprintf' ccj4A3N3.ltrans0.o:(.text+0x98e): undefined reference to `rpl_fprintf' ccj4A3N3.ltrans0.o:(.text+0x9ed): undefined reference to `get_stat_mtime' .... /var/tmp/portage/app-arch/gzip-1.6/temp/ccj4A3N3.ltrans6.ltrans.o:ccj4A3N3.ltrans6.o:(.text+0x145): more undefined references to `rpl_fprintf' follow collect2: error: ld returned 1 exit status Makefile:1545: recipe for target 'gzip' failed make[2]: *** [gzip] Error 1 make[2]: Leaving directory '/var/tmp/portage/app-arch/gzip-1.6/work/gzip-1.6' Makefile:1669: recipe for target 'all-recursive' failed make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory '/var/tmp/portage/app-arch/gzip-1.6/work/gzip-1.6' Makefile:1455: recipe for target 'all' failed make: *** [all] Error 2 * ERROR: app-arch/gzip-1.6::gentoo failed (compile phase): * emake failed * * If you need support, post the output of `emerge --info '=app-arch/gzip-1.6::gentoo'`, * the complete build log and the output of `emerge -pqv '=app-arch/gzip-1.6::gentoo'`. * The complete build log is located at '/var/tmp/portage/app-arch/gzip-1.6/temp/build.log'. * The ebuild environment file is located at '/var/tmp/portage/app-arch/gzip-1.6/temp/environment'. * Working directory: '/var/tmp/portage/app-arch/gzip-1.6/work/gzip-1.6' * S: '/var/tmp/portage/app-arch/gzip-1.6/work/gzip-1.6' Expected Results: 1. mkdir -p /usr/x86_64-pc-linux-gnu/binutils-bin/lib/bfd-plugins 2. ln -s /usr/libexec/gcc/x86_64-pc-linux-gnu/4.9.2/liblto_plugin.so /usr/x86_64-pc-linux-gnu/binutils-bin/lib/bfd-plugins/ 3. place -flto in CFLAGS and LDFLAGS in /etc/portage/make.conf 4. emerge --oneshot gzip Calculating dependencies... done! >>> Verifying ebuild manifests >>> Emerging (1 of 1) app-arch/gzip-1.6::gentoo >>> Installing (1 of 1) app-arch/gzip-1.6::gentoo >>> Jobs: 1 of 1 complete Load avg: 0.91, 0.60, 0.43 >>> Auto-cleaning packages... >>> No outdated packages were found on your system. it is interesting that ld.gold also looks in bfd-plugins folder and does not look in gold-plugins the advantage of -flto: ls -l /bin/gzip ld.bfd without -flto 98064 ld.bfd with -flto 89776 ld.gold without -flto 96000 ld.gold with -flto 87768
*** This bug has been marked as a duplicate of bug 494228 ***
