x/debug/cmd/viewcore: does not build on aix-ppc64

[bcmills]

The x/debug build is consistently failing on the aix-ppc64 builder.
It appears that x/debug depends on github.com/chzyer/readline, but that package is missing an aix implementation.

CC @chzyer @Helflym

aix-ppc64 at 67f181bfd84dfd5942fe9a29d8a20c9ce5eb2fea building debug at 621e2d3f35dac46daf912f8d9d2fabd57d022520

:: Running /ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/bin/go with args ["/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/bin/go" "test" "-short" "golang.org/x/debug/..."] and env ["TERM=dumb" "AUTHSTATE=compat" "SHELL=/usr/bin/ksh" "HOME=/" "USER=root" "PATH=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go/bin:/opt/freeware/bin:/usr/bin:/etc:/usr/sbin:/usr/ucb:/usr/bin/X11:/sbin:/usr/java7_64/jre/bin:/usr/java7_64/bin" "TZ=CST6CDT" "LANG=en_US" "LOCPATH=/usr/lib/nls/loc" "LC__FASTMSG=true" "ODMDIR=/etc/objrepos" "CLCMD_PASSTHRU=1" "LOGNAME=root" "LOGIN=root" "META_BUILDLET_BINARY_URL=https://storage.googleapis.com/go-builder-data/buildlet.aix-ppc64" "GO_STAGE0_NET_DELAY=300ms" "GO_STAGE0_DL_DELAY=100ms" "NLSPATH=/usr/lib/nls/msg/%L/%N:/usr/lib/nls/msg/%L/%N.cat:/usr/lib/nls/msg/%l.%c/%N:/usr/lib/nls/msg/%l.%c/%N.cat" "WORKDIR=/ramdisk8GB/workdir-host-aix-ppc64-osuosl" "GOROOT_BOOTSTRAP=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go1.4" "GO_BUILDER_NAME=aix-ppc64" "GOROOT_BOOTSTRAP=/opt/freeware/lib/golang" "PATH=/opt/freeware/bin:/usr/bin:/etc:/usr/sbin:/usr/ucb:/usr/bin/X11:/sbin:/usr/java7_64/jre/bin:/usr/java7_64/bin" "GOROOT=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/go" "GOPATH=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/gopath" "GOPROXY=http://10.240.0.23:30157" "GOPROXY=https://proxy.golang.org" "TMPDIR=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/tmp" "GOCACHE=/ramdisk8GB/workdir-host-aix-ppc64-osuosl/gocache"] in dir /ramdisk8GB/workdir-host-aix-ppc64-osuosl/gopath/src/golang.org/x/debug

go: downloading github.com/spf13/cobra v0.0.3
go: downloading github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
go: extracting github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
go: extracting github.com/spf13/cobra v0.0.3
go: downloading github.com/spf13/pflag v1.0.3
go: extracting github.com/spf13/pflag v1.0.3
go: finding github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e
go: finding github.com/spf13/pflag v1.0.3
go: finding github.com/spf13/cobra v0.0.3
# github.com/chzyer/readline
../../../../pkg/mod/github.com/chzyer/readline@v0.0.0-20180603132655-2972be24d48e/utils.go:241:9: undefined: State
ok  	golang.org/x/debug/internal/core	0.031s

[bcmills]

@golang/osp-team, should we simply disable the aix-ppc64 on this repo for now?

[dmitshur]

In #31564 (comment), @Helflym said "my aim is to have all x/ packages working for 1.13." If that still holds and applies to x/debug, we can do the same as for x/net and make the builders require Go 1.13. That'll buy time, and if we want to disable it completely later, we can do that.

[dmitshur]

Doing what I said above is trickier than I thought. The current version of cmd/coordinator has atLeastGo1 helper to conditionally limit to a specific version of Go. But it doesn't exclude master branch. I understand atLeastGo1 was designed to cut off too-old versions of Go, not to target not-yet-released future versions of Go.

The difference with x/net is that x/net is passing on master branch, but not Go 1.12 release branch. But x/debug is failing on all branches, including master.

So for now our option is to disable it completely and update that as x/debug gains aix-ppc64 support. I'll wait a bit to give aix-ppc64 owners a chance to comment on their plans for x/debug support before sending that CL.

[Helflym]

I've already created a PR in chzyer/readline package in order to add AIX support (chzyer/readline#175). However, this package seems no longer supported..
This is the only problem with this package (at least locally).

Note that if it's happening with AIX, it might happen to every new GOOS/GOARCH. I'm not sure having a subrepos package depending on a external package is a good idea. If we want all subrepos to be green, we should be able to submit patches and fixes directly inside Gerrit.

Anyway, if you wish to disable it until either the PR is accepted or a better solution is created, go for it.

[bcmills]

The dependency comes from cmd/viewcore/main.go in CL 115597 (CC @hyangah, @randall77, @heschik).

[gopherbot]

Change https://golang.org/cl/192322 mentions this issue: cmd/viewcore: skip build on aix

[millerresearch]

github.com/chzyer/readline doesn't build on Plan 9 either. I'll submit a CL with a +build !plan9 to stop the x/debug repo builder tests failing on Plan 9.

[gopherbot]

Change https://golang.org/cl/229877 mentions this issue: cmd/viewcore: skip build on plan9