net: TestLookupDotsWithLocalSource fails

[darkfeline]

What version of Go are you using (go version)?

$ go version
go version go1.11.4 linux/amd64

Does this issue reproduce with the latest release?

Yes, 1.11.4 is the latest (not counting betas?).

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ionasal/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/ionasal/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/lib/go"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build457575040=/tmp/go-build -gno-record-gcc-switches"

What did you do?

mkdir -p /tmp/tmp3
cd /tmp/tmp3
go mod init example.com/test
cat >main.go <<EOF
package foo

import (
	_ "net"
)
EOF
go test all

What did you expect to see?

All tests pass

What did you see instead?

Test failures:

--- FAIL: TestLookupDotsWithLocalSource (0.00s)
    lookup_test.go:612: netgo: got localhost.; want localhost
FAIL
FAIL	net	29.770s

This appears to be a regression of or related to #15881

[bcmills]

CC @mikioh @bradfitz @ianlancetaylor for net

[bcmills]

This test passes under all recent releases for me on recent Debian; I'm guessing it's something distro-specific. What distribution and version are you running? (Please attach the output of uname -v and lsb_release -a.)

scratch$ go mod init golang.org/issue/scratch
go: creating new go.mod: module golang.org/issue/scratch

scratch$ go1.11.4 test -v -run=TestLookupDotsWithLocalSource net
=== RUN   TestLookupDotsWithLocalSource
--- PASS: TestLookupDotsWithLocalSource (0.00s)
PASS
ok      net     (cached)

scratch$ go1.11.5 test -v -run=TestLookupDotsWithLocalSource net
=== RUN   TestLookupDotsWithLocalSource
--- PASS: TestLookupDotsWithLocalSource (0.00s)
PASS
ok      net     (cached)

scratch$ go1.12beta2 test -v -run=TestLookupDotsWithLocalSource net
=== RUN   TestLookupDotsWithLocalSource
--- PASS: TestLookupDotsWithLocalSource (0.00s)
PASS
ok      net     0.032s

[bcmills]

This test appears to be a regression test for #13564, and was refactored to be more permissive in #14050.

[darkfeline]

This is on Arch Linux.

$ uname -v
#1 SMP PREEMPT Wed Jan 16 22:38:58 UTC 2019
$ uname -a
Linux myhost 4.20.3-arch1-1-ARCH #1 SMP PREEMPT Wed Jan 16 22:38:58 UTC 2019 x86_64 GNU/Linux

(no lsb-release provided by default)

[darkfeline]

I fixed this by adding 127.0.0.1 localhost to /etc/hosts.