dashboard: remove obsolete disabled builders

FreeBSD 9.3, FreeBSD 10.x, and OpenBSD 6.0 have
reached end-of-life and are no longer supported.
Go 1.12 was the last release¹ that ran on FreeBSD 10.x.
Go 1.10 was the last release² that ran on OpenBSD 6.0.

These builders have long since been disabled and won't be needed in
the future, so remove them. This work helped detect golang/go#40563.

Modify TestHostConfigsAllUsed to report errors instead of warnings
when it finds unused host configs. Make a map of known exceptions
with rationale or a linked issue for each entry.

¹ https://golang.org/doc/go1.12#ports
² https://golang.org/doc/go1.10#ports

Updates golang/go#36841.
Updates golang/go#19938.

Change-Id: Id7fcdc671bfacf7e70174f4168c9c9cc46ba53d7
Reviewed-on: https://go-review.googlesource.com/c/build/+/246639
Reviewed-by: Alexander Rakoczy <[email protected]>

Author: dmitshur

dashboard/builders.go

@@ -223,24 +223,6 @@ var Hosts = map[string]*HostConfig{
 		OwnerGithub: "bradfitz", // at home
 		env:         []string{"GOROOT_BOOTSTRAP=/usr/local/goboot"},
 	},
-	"host-openbsd-amd64-60": &HostConfig{
-		VMImage:     "openbsd-amd64-60",
-		machineType: "n1-highcpu-4",
-		// OpenBSD 6.0 requires binaries built with Go 1.10, per https://golang.org/wiki/OpenBSD
-		buildletURLTmpl:    "https://storage.googleapis.com/$BUCKET/buildlet.openbsd-amd64.go1.10",
-		goBootstrapURLTmpl: "https://storage.googleapis.com/$BUCKET/gobootstrap-openbsd-amd64-60.tar.gz",
-		Notes:              "OpenBSD 6.0; GCE VM is built from script in build/env/openbsd-amd64",
-		SSHUsername:        "gopher",
-	},
-	"host-openbsd-386-60": &HostConfig{
-		VMImage:     "openbsd-386-60",
-		machineType: "n1-highcpu-4",
-		// OpenBSD 6.0 requires binaries built with Go 1.10, per https://golang.org/wiki/OpenBSD
-		buildletURLTmpl:    "https://storage.googleapis.com/$BUCKET/buildlet.openbsd-386.go1.10",
-		goBootstrapURLTmpl: "https://storage.googleapis.com/$BUCKET/gobootstrap-openbsd-386-60.tar.gz",
-		Notes:              "OpenBSD 6.0; GCE VM is built from script in build/env/openbsd-386",
-		SSHUsername:        "gopher",
-	},
 	"host-openbsd-amd64-62": &HostConfig{
 		VMImage:            "openbsd-amd64-62",
 		machineType:        "n1-highcpu-4",
@@ -280,30 +262,6 @@ var Hosts = map[string]*HostConfig{
 		env:         []string{"GOROOT_BOOTSTRAP=/usr/local/go"},
 		OwnerGithub: "4a6f656c",
 	},
-	"host-freebsd-93-gce": &HostConfig{
-		VMImage:            "freebsd-amd64-gce93",
-		machineType:        "n1-highcpu-4",
-		buildletURLTmpl:    "https://storage.googleapis.com/$BUCKET/buildlet.freebsd-amd64",
-		goBootstrapURLTmpl: "https://storage.googleapis.com/$BUCKET/go1.4-freebsd-amd64.tar.gz",
-		SSHUsername:        "gopher",
-	},
-	"host-freebsd-10_3": &HostConfig{
-		VMImage:            "freebsd-amd64-103-b",
-		Notes:              "FreeBSD 10.3; GCE VM is built from script in build/env/freebsd-amd64",
-		machineType:        "n1-highcpu-4",
-		buildletURLTmpl:    "https://storage.googleapis.com/$BUCKET/buildlet.freebsd-amd64",
-		goBootstrapURLTmpl: "https://storage.googleapis.com/$BUCKET/go1.4-freebsd-amd64.tar.gz",
-		env:                []string{"CC=clang"},
-		SSHUsername:        "gopher",
-	},
-	"host-freebsd-10_4": &HostConfig{
-		VMImage:            "freebsd-amd64-104",
-		Notes:              "FreeBSD 10.4; GCE VM is built from script in build/env/freebsd-amd64",
-		machineType:        "n1-highcpu-4",
-		buildletURLTmpl:    "https://storage.googleapis.com/$BUCKET/buildlet.freebsd-amd64",
-		goBootstrapURLTmpl: "https://storage.googleapis.com/$BUCKET/go1.4-freebsd-amd64.tar.gz",
-		SSHUsername:        "gopher",
-	},
 	"host-freebsd-11_1": &HostConfig{
 		VMImage:            "freebsd-amd64-111-b",
 		Notes:              "FreeBSD 11.1; GCE VM is built from script in build/env/freebsd-amd64",
@@ -1442,29 +1400,6 @@ func explicitTrySet(projs ...string) func(proj, branch, goBranch string) bool {
 }
 
 func init() {
-	addBuilder(BuildConfig{
-		Name:       "freebsd-amd64-gce93",
-		HostType:   "host-freebsd-93-gce",
-		buildsRepo: disabledBuilder,
-	})
-	addBuilder(BuildConfig{
-		Name:     "freebsd-amd64-10_3",
-		HostType: "host-freebsd-10_3",
-		buildsRepo: func(repo, branch, goBranch string) bool {
-			return goBranch == "release-branch.go1.12" && buildRepoByDefault(repo)
-		},
-		tryBot: func(repo, branch, goBranch string) bool {
-			return branch == "release-branch.go1.12"
-		},
-	})
-	addBuilder(BuildConfig{
-		Name:     "freebsd-amd64-10_4",
-		HostType: "host-freebsd-10_4",
-		buildsRepo: func(repo, branch, goBranch string) bool {
-			return goBranch == "release-branch.go1.12" && buildRepoByDefault(repo)
-		},
-		tryBot: nil,
-	})
 	addBuilder(BuildConfig{
 		Name:     "freebsd-amd64-11_1",
 		HostType: "host-freebsd-11_1",
@@ -1505,22 +1440,6 @@ func init() {
 		Name:     "freebsd-amd64-race",
 		HostType: "host-freebsd-11_1-big", // TODO(golang.org/issue/40562): Update to newer FreeBSD.
 	})
-	addBuilder(BuildConfig{
-		Name:     "freebsd-386-10_3",
-		HostType: "host-freebsd-10_3",
-		buildsRepo: func(repo, branch, goBranch string) bool {
-			return goBranch == "release-branch.go1.12" && buildRepoByDefault(repo)
-		},
-		env: []string{"GOARCH=386", "GOHOSTARCH=386"},
-	})
-	addBuilder(BuildConfig{
-		Name:     "freebsd-386-10_4",
-		HostType: "host-freebsd-10_4",
-		buildsRepo: func(repo, branch, goBranch string) bool {
-			return goBranch == "release-branch.go1.12" && buildRepoByDefault(repo)
-		},
-		env: []string{"GOARCH=386", "GOHOSTARCH=386"},
-	})
 	addBuilder(BuildConfig{
 		Name:           "freebsd-386-11_1",
 		HostType:       "host-freebsd-11_1",
@@ -1883,6 +1802,7 @@ func init() {
 		HostType: "host-nacl",
 		buildsRepo: func(repo, branch, goBranch string) bool {
 			// nacl support is removed in Go 1.14.
+			// TODO: Remove builder after Go 1.15 is out.
 			return repo == "go" && !atLeastGo1(goBranch, 14) && !strings.HasPrefix(goBranch, "dev.")
 		},
 		numTryTestHelpers: 3,
@@ -1893,6 +1813,7 @@ func init() {
 		HostType: "host-nacl",
 		buildsRepo: func(repo, branch, goBranch string) bool {
 			// nacl support is removed in Go 1.14.
+			// TODO: Remove builder after Go 1.15 is out.
 			return repo == "go" && !atLeastGo1(goBranch, 14) && !strings.HasPrefix(goBranch, "dev.")
 		},
 		tryBot:            explicitTrySet("go"),
@@ -1933,27 +1854,6 @@ func init() {
 			"GO_DISABLE_OUTBOUND_NETWORK=1",
 		},
 	})
-	addBuilder(BuildConfig{
-		Name:              "openbsd-amd64-60",
-		HostType:          "host-openbsd-amd64-60",
-		distTestAdjust:    noTestDirAndNoReboot,
-		buildsRepo:        disabledBuilder,
-		numTestHelpers:    2,
-		numTryTestHelpers: 5,
-	})
-	addBuilder(BuildConfig{
-		Name:           "openbsd-386-60",
-		HostType:       "host-openbsd-386-60",
-		distTestAdjust: noTestDirAndNoReboot,
-		buildsRepo:     disabledBuilder,
-		env: []string{
-			// cmd/go takes ~192 seconds on openbsd-386
-			// now, which is over the 180 second default
-			// dist test timeout. So, bump this builder
-			// up:
-			"GO_TEST_TIMEOUT_SCALE=2",
-		},
-	})
 	addBuilder(BuildConfig{
 		Name:           "openbsd-386-62",
 		HostType:       "host-openbsd-386-62",

dashboard/builders_test.go

@@ -356,21 +356,9 @@ func TestBuilderConfig(t *testing.T) {
 		// go1.12.html: "Go 1.12 is the last release that is
 		// supported on FreeBSD 10.x [... and 11.1]"
 		// But golang.org/issue/40563 happened.
-		{b("freebsd-386-10_3", "go"), none},
-		{b("freebsd-386-10_3", "net"), none},
-		{b("freebsd-386-10_3", "mobile"), none},
-		{b("freebsd-amd64-10_3", "go"), none},
-		{b("freebsd-amd64-10_3", "net"), none},
-		{b("freebsd-amd64-10_3", "mobile"), none},
 		{b("freebsd-amd64-11_1", "go"), none},
 		{b("freebsd-amd64-11_1", "net"), none},
 		{b("freebsd-amd64-11_1", "mobile"), none},
-		{b("[email protected]", "go"), both},
-		{b("[email protected]", "[email protected]"), both},
-		{b("[email protected]", "mobile"), none},
-		{b("[email protected]", "go"), isBuilder},
-		{b("[email protected]", "net"), isBuilder},
-		{b("[email protected]", "mobile"), none},
 		{b("[email protected]", "go"), isBuilder},
 		{b("[email protected]", "net"), isBuilder},
 		{b("[email protected]", "mobile"), none},
@@ -425,6 +413,8 @@ func TestBuilderConfig(t *testing.T) {
 		{b("android-amd64-emu", "go"), isBuilder},
 		{b("android-386-emu", "go"), isBuilder},
 
+		// golang.org/doc/go1.13: "Go 1.13 is the last release
+		// that will run on Native Client (NaCl)."
 		{b("nacl-386", "go"), none},
 		{b("[email protected]", "go"), none},
 		{b("[email protected]", "go"), onlyPost},
@@ -487,13 +477,9 @@ func TestBuilderConfig(t *testing.T) {
 		{b("darwin-amd64-10_15", "exp"), onlyPost},
 		// ... but not on most others:
 		{b("darwin-amd64-10_12", "exp"), none},
-		{b("[email protected]", "exp"), none},
-		{b("[email protected]", "exp"), none},
 		{b("[email protected]", "exp"), none},
 		{b("freebsd-386-11_2", "exp"), none},
 		{b("freebsd-386-12_0", "exp"), none},
-		{b("[email protected]", "exp"), none},
-		{b("[email protected]", "exp"), none},
 		{b("[email protected]", "exp"), none},
 		{b("freebsd-amd64-11_2", "exp"), none},
 		{b("freebsd-amd64-12_0", "exp"), none},
@@ -519,8 +505,6 @@ func TestBuilderConfig(t *testing.T) {
 		{b("linux-amd64-sid", "build"), none},
 		{b("linux-amd64-nocgo", "build"), none},
 		{b("linux-386-longtest", "build"), none},
-		{b("freebsd-386-10_3", "build"), none},
-		{b("freebsd-386-10_4", "build"), none},
 		{b("freebsd-386-11_1", "build"), none},
 		{b("js-wasm", "build"), none},
 		{b("android-386-emu", "build"), none},
@@ -606,16 +590,27 @@ func TestBuilderConfig(t *testing.T) {
 }
 
 func TestHostConfigsAllUsed(t *testing.T) {
-	used := map[string]bool{}
+	knownUnused := map[string]bool{
+		// Currently host-linux-armhf-cross and host-linux-armel-cross aren't
+		// referenced, but the coordinator hard-codes them, so don't make
+		// these two an error for now.
+		"host-linux-armhf-cross": true,
+		"host-linux-armel-cross": true,
+
+		"host-linux-x86-alpine": true, // TODO(golang.org/issue/19938): Fix the Alpine builder, or remove it.
+		"host-linux-arm64-aws":  true, // TODO(golang.org/issue/36841): Add a builder that uses this host, or remove it.
+	}
+
+	used := make(map[string]bool)
 	for _, conf := range Builders {
 		used[conf.HostType] = true
 	}
 	for hostType := range Hosts {
-		if !used[hostType] {
-			// Currently host-linux-armhf-cross and host-linux-armel-cross aren't
-			// referenced, but the coordinator hard-codes them, so don't make
-			// this an error for now.
-			t.Logf("warning: host type %q is not referenced from any build config", hostType)
+		if !used[hostType] && !knownUnused[hostType] {
+			t.Errorf("host type %q is not referenced from any build config", hostType)
+		}
+		if used[hostType] && knownUnused[hostType] {
+			t.Errorf("host type %q should not be listed in knownUnused since it's in use", hostType)
 		}
 	}
 }