$ emerge -va dev-lang/go

These are the packages that would be merged, in order:

Calculating dependencies               ... done!
[ebuild  N     ] dev-lang/go-1.8:0/1.8::gentoo_prefix  USE="-gccgo" 68725 KiB

Total: 1 package (1 new), Size of downloads: 68725 KiB

Would you like to merge these packages? [Yes/No] 

>>> Verifying ebuild manifests
>>> Running pre-merge checks for dev-lang/go-1.8

>>> Emerging (1 of 1) dev-lang/go-1.8::gentoo_prefix
>>> Downloading 'http://distfiles.gentoo.org/distfiles/go1.8.src.tar.gz'
--2017-02-22 15:29:08--  http://distfiles.gentoo.org/distfiles/go1.8.src.tar.gz
Resolving distfiles.gentoo.org (distfiles.gentoo.org)... 64.50.233.100, 216.165.129.135, 137.226.34.46, ...
Connecting to distfiles.gentoo.org (distfiles.gentoo.org)|64.50.233.100|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 15320083 (15M) [application/x-gzip]
Saving to: '/opt/gentoo/var/cache/portage/dist/go1.8.src.tar.gz'

/opt/gentoo/var/cac 100%[===================>]  14.61M  3.02MB/s    in 5.3s    

2017-02-22 15:29:15 (2.76 MB/s) - '/opt/gentoo/var/cache/portage/dist/go1.8.src.tar.gz' saved [15320083/15320083]

 * go1.8.src.tar.gz SHA256 SHA512 WHIRLPOOL size ;-) ...                                                                                                                    [ ok ]
>>> Downloading 'http://distfiles.gentoo.org/distfiles/go-darwin-amd64-bootstrap-1.8.tbz'
--2017-02-22 15:29:15--  http://distfiles.gentoo.org/distfiles/go-darwin-amd64-bootstrap-1.8.tbz
Resolving distfiles.gentoo.org (distfiles.gentoo.org)... 64.50.233.100, 216.165.129.135, 137.226.34.46, ...
Connecting to distfiles.gentoo.org (distfiles.gentoo.org)|64.50.233.100|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 55053831 (53M) [application/x-troff-man]
Saving to: '/opt/gentoo/var/cache/portage/dist/go-darwin-amd64-bootstrap-1.8.tbz'

/opt/gentoo/var/cac 100%[===================>]  52.50M  5.74MB/s    in 12s     

2017-02-22 15:29:27 (4.46 MB/s) - '/opt/gentoo/var/cache/portage/dist/go-darwin-amd64-bootstrap-1.8.tbz' saved [55053831/55053831]

 * go-darwin-amd64-bootstrap-1.8.tbz SHA256 SHA512 WHIRLPOOL size ;-) ...                                                                                                   [ ok ]
>>> Unpacking source...
>>> Unpacking go1.8.src.tar.gz to /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work
>>> Unpacking go-darwin-amd64-bootstrap-1.8.tbz to /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work
>>> Source unpacked in /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work
>>> Preparing source in /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go ...
>>> Source prepared.
>>> Configuring source in /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go ...
>>> Source configured.
>>> Compiling source in /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go ...
 * GOROOT_BOOTSTRAP is /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go-darwin-amd64-bootstrap
##### Building Go bootstrap tool.
cmd/dist

##### Building Go toolchain using /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go-darwin-amd64-bootstrap.
bootstrap/cmd/internal/dwarf
bootstrap/cmd/internal/bio
bootstrap/cmd/internal/sys
bootstrap/cmd/compile/internal/syntax
bootstrap/math/big
bootstrap/debug/pe
bootstrap/cmd/internal/gcprog
bootstrap/cmd/asm/internal/flags
bootstrap/cmd/internal/obj
bootstrap/cmd/internal/obj/arm64
bootstrap/cmd/internal/obj/mips
bootstrap/cmd/internal/obj/arm
bootstrap/cmd/internal/obj/ppc64
bootstrap/cmd/internal/obj/x86
bootstrap/cmd/internal/obj/s390x
bootstrap/cmd/asm/internal/lex
bootstrap/cmd/link/internal/ld
bootstrap/cmd/compile/internal/ssa
bootstrap/cmd/asm/internal/arch
bootstrap/cmd/asm/internal/asm
bootstrap/cmd/asm
bootstrap/cmd/link/internal/amd64
bootstrap/cmd/link/internal/arm
bootstrap/cmd/link/internal/arm64
bootstrap/cmd/link/internal/mips
bootstrap/cmd/link/internal/mips64
bootstrap/cmd/link/internal/ppc64
bootstrap/cmd/link/internal/s390x
bootstrap/cmd/link/internal/x86
bootstrap/cmd/link
bootstrap/cmd/compile/internal/gc
bootstrap/cmd/compile/internal/arm
bootstrap/cmd/compile/internal/amd64
bootstrap/cmd/compile/internal/arm64
bootstrap/cmd/compile/internal/mips
bootstrap/cmd/compile/internal/mips64
bootstrap/cmd/compile/internal/ppc64
bootstrap/cmd/compile/internal/s390x
bootstrap/cmd/compile/internal/x86
bootstrap/cmd/compile

##### Building go_bootstrap for host, darwin/amd64.
runtime/internal/sys
runtime/internal/atomic
runtime
internal/syscall/windows/sysdll
sync/atomic
unicode/utf16
unicode/utf8
unicode
encoding
math
internal/race
errors
sync
internal/singleflight
io
syscall
hash
strings
bytes
hash/adler32
strconv
bufio
path
internal/syscall/windows
internal/syscall/windows/registry
crypto
encoding/base64
reflect
time
crypto/sha1
os
os/signal
encoding/binary
fmt
sort
path/filepath
regexp/syntax
container/heap
io/ioutil
context
compress/flate
net/url
debug/dwarf
encoding/json
text/template/parse
log
go/token
flag
os/exec
go/scanner
regexp
go/ast
compress/zlib
text/template
debug/macho
debug/elf
go/parser
go/doc
go/build
cmd/go

##### Building packages and commands for darwin/amd64.
runtime/internal/sys
runtime/internal/atomic
runtime
errors
internal/race
sync/atomic
unicode
unicode/utf8
math
container/list
container/ring
crypto/subtle
crypto/internal/cipherhw
internal/nettrace
vendor/golang_org/x/crypto/curve25519
encoding
unicode/utf16
vendor/golang_org/x/crypto/poly1305
image/color
internal/syscall/windows
internal/syscall/windows/registry
internal/syscall/windows/sysdll
runtime/race
sync
cmd/compile/internal/test
cmd/vet/internal/whitelist
image/color/palette
io
syscall
internal/singleflight
bytes
strings
hash
crypto/cipher
runtime/trace
hash/adler32
hash/fnv
crypto/hmac
hash/crc64
hash/crc32
bufio
text/tabwriter
vendor/golang_org/x/text/transform
html
path
strconv
math/rand
math/cmplx
time
reflect
crypto/aes
crypto
crypto/rc4
encoding/base64
encoding/ascii85
encoding/base32
image
crypto/sha512
crypto/sha1
crypto/md5
crypto/sha256
os
image/internal/imageutil
image/draw
image/jpeg
os/signal
vendor/golang_org/x/net/route
fmt
encoding/binary
sort
path/filepath
regexp/syntax
compress/bzip2
container/heap
encoding/pem
runtime/debug
cmd/internal/sys
crypto/des
vendor/golang_org/x/crypto/chacha20poly1305/internal/chacha20
vendor/golang_org/x/crypto/chacha20poly1305
io/ioutil
cmd/internal/dwarf
flag
log
debug/dwarf
compress/flate
debug/gosym
debug/plan9obj
cmd/vendor/golang.org/x/arch/arm/armasm
cmd/vendor/golang.org/x/arch/x86/x86asm
archive/tar
compress/lzw
context
cmd/vendor/golang.org/x/arch/ppc64/ppc64asm
math/big
encoding/hex
go/token
regexp
os/exec
database/sql/driver
cmd/internal/obj
go/scanner
database/sql
encoding/csv
compress/zlib
archive/zip
compress/gzip
go/ast
encoding/gob
encoding/json
encoding/xml
vendor/golang_org/x/net/http2/hpack
vendor/golang_org/x/net/idna
vendor/golang_org/x/text/unicode/norm
debug/elf
debug/macho
debug/pe
cmd/internal/goobj
vendor/golang_org/x/text/width
mime
mime/quotedprintable
net/http/internal
net/url
text/template/parse
text/scanner
image/gif
image/png
index/suffixarray
internal/pprof/profile
cmd/internal/objfile
testing
internal/trace
net/internal/socktest
go/parser
go/printer
testing/iotest
crypto/dsa
crypto/elliptic
encoding/asn1
crypto/rand
go/constant
testing/quick
text/template
cmd/internal/obj/arm
cmd/addr2line
internal/testenv
crypto/rsa
cmd/internal/obj/arm64
cmd/internal/obj/mips
cmd/internal/obj/ppc64
cmd/internal/obj/s390x
cmd/internal/obj/x86
crypto/ecdsa
crypto/x509/pkix
go/types
cmd/asm/internal/flags
cmd/cgo
go/format
runtime/pprof/internal/protopprof
cmd/asm/internal/lex
runtime/pprof
cmd/internal/bio
cmd/compile/internal/syntax
go/doc
html/template
testing/internal/testdeps
cmd/internal/gcprog
cmd/internal/browser
cmd/dist
cmd/fix
cmd/gofmt
cmd/link/internal/ld
go/build
cmd/nm
cmd/objdump
cmd/pack
cmd/pprof/internal/plugin
cmd/cover
cmd/doc
cmd/pprof/internal/report
cmd/pprof/internal/svg
cmd/pprof/internal/tempfile
cmd/pprof/internal/symbolizer
cmd/pprof/internal/symbolz
cmd/vet/internal/cfg
cmd/asm/internal/arch
cmd/compile/internal/ssa
cmd/pprof/internal/commands
cmd/pprof/internal/driver
cmd/asm/internal/asm
go/internal/gccgoimporter
go/internal/gcimporter
cmd/api
runtime/cgo
cmd/asm
go/importer
cmd/vet
cmd/link/internal/amd64
cmd/link/internal/arm
cmd/link/internal/arm64
cmd/link/internal/mips
cmd/link/internal/mips64
cmd/link/internal/s390x
cmd/link/internal/ppc64
cmd/link/internal/x86
cmd/link
# runtime/cgo
clang-3.9: error: unsupported option '--gdwarf2'
cmd/compile/internal/gc
cmd/compile/internal/amd64
cmd/compile/internal/arm
cmd/compile/internal/arm64
cmd/compile/internal/mips
cmd/compile/internal/mips64
cmd/compile/internal/ppc64
cmd/compile/internal/s390x
cmd/compile/internal/x86
cmd/compile
 * ERROR: dev-lang/go-1.8::gentoo_prefix failed (compile phase):
 *   build failed
 * 
 * Call stack:
 *     ebuild.sh, line 115:  Called __call-ebuildshell 'src_compile'
 *     ebuild.sh, line 529:  Called src_compile
 *   environment, line 1120:  Called die
 * The specific snippet of code:
 *       ./make.bash || die "build failed"
 * 
 * If you need support, post the output of `emerge --info '=dev-lang/go-1.8::gentoo_prefix'`,
 * the complete build log and the output of `emerge -pqv '=dev-lang/go-1.8::gentoo_prefix'`.
 * The complete build log is located at '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/temp/build.log.gz'.
 * The ebuild environment file is located at '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/temp/environment'.
 * Working directory: '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go/src'
 * S: '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go'

>>> Failed to emerge dev-lang/go-1.8, Log file:

>>>  '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/temp/build.log.gz'

 * Messages for package dev-lang/go-1.8:

 * GOROOT_BOOTSTRAP is /Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go-darwin-amd64-bootstrap
 * ERROR: dev-lang/go-1.8::gentoo_prefix failed (compile phase):
 *   build failed
 * 
 * Call stack:
 *     ebuild.sh, line 115:  Called __call-ebuildshell 'src_compile'
 *     ebuild.sh, line 529:  Called src_compile
 *   environment, line 1120:  Called die
 * The specific snippet of code:
 *       ./make.bash || die "build failed"
 * 
 * If you need support, post the output of `emerge --info '=dev-lang/go-1.8::gentoo_prefix'`,
 * the complete build log and the output of `emerge -pqv '=dev-lang/go-1.8::gentoo_prefix'`.
 * The complete build log is located at '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/temp/build.log.gz'.
 * The ebuild environment file is located at '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/temp/environment'.
 * Working directory: '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go/src'
 * S: '/Volumes/Scratch/tmp/portage/dev-lang/go-1.8/work/go'