greplogs: set more flag defaults when --triage is set

Also omit builders with known issues when --triage is set.

For golang/go#52653.

Author: Bryan C. Mills

Diff for: greplogs/_embed/broken.go

@@ -0,0 +1,26 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Command broken lists the current Go builders with known issues.
+//
+// To test this program, cd to its directory and run:
+// 	go mod init
+// 	go get golang.org/x/build/dashboard@HEAD
+// 	go run .
+// 	rm go.mod go.sum
+package main
+
+import (
+	"fmt"
+
+	"golang.org/x/build/dashboard"
+)
+
+func main() {
+	for _, b := range dashboard.Builders {
+		if len(b.KnownIssues) > 0 {
+			fmt.Println(b.Name)
+		}
+	}
+}

Diff for: greplogs/broken.go

@@ -0,0 +1,76 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	_ "embed"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"strings"
+)
+
+//go:embed _embed/broken.go
+var brokenScript []byte
+
+// listBrokenBuilders returns the builders that are marked
+// as broken in golang.org/x/build/dashboard at HEAD.
+func listBrokenBuilders() (broken []string, err error) {
+	defer func() {
+		if err != nil {
+			err = fmt.Errorf("identifying broken builders: %v", err)
+		}
+	}()
+
+	modDir, err := os.MkdirTemp("", "greplogs")
+	if err != nil {
+		return nil, err
+	}
+	defer func() {
+		removeErr := os.RemoveAll(modDir)
+		if err == nil {
+			err = removeErr
+		}
+	}()
+
+	runCommand := func(name string, args ...string) ([]byte, error) {
+		cmd := exec.Command(name, args...)
+		cmd.Dir = modDir
+		cmd.Env = append(os.Environ(), "GO111MODULE=on", "PWD="+modDir)
+		cmd.Stderr = new(strings.Builder)
+
+		out, err := cmd.Output()
+		if err != nil {
+			return out, fmt.Errorf("%s: %w\nstderr:\n%s", strings.Join(cmd.Args, " "), err, cmd.Stderr)
+		}
+		return out, nil
+	}
+
+	_, err = runCommand("go", "mod", "init", "github.com/aclements/go-misc/greplogs/_embed")
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = runCommand("go", "get", "golang.org/x/build/dashboard@HEAD")
+	if err != nil {
+		return nil, err
+	}
+
+	err = os.WriteFile(filepath.Join(modDir, "broken.go"), brokenScript, 0644)
+	if err != nil {
+		return nil, err
+	}
+
+	out, err := runCommand("go", "run", "broken.go")
+	if err != nil {
+		return nil, err
+	}
+
+	broken = strings.Split(strings.TrimSpace(string(out)), "\n")
+	sort.Strings(broken)
+	return broken, nil
+}

Diff for: greplogs/main.go

@@ -64,6 +64,8 @@ const (
 	colorMatch     = colorBold | colorFgRed
 )
 
+var brokenBuilders []string
+
 func main() {
 	// XXX What I want right now is just to point it at a bunch of
 	// logs and have it extract the failures.
@@ -91,6 +93,29 @@ func main() {
 		os.Exit(2)
 	}
 
+	if *flagTriage {
+		*flagFilesOnly = true
+		if len(failRegexps) == 0 && len(fileRegexps) == 0 {
+			failRegexps.Set(".")
+		}
+
+		if before.Time.IsZero() {
+			year, month, day := time.Now().UTC().Date()
+			before = timeFlag{Time: time.Date(year, month, day, 0, 0, 0, 0, time.UTC)}
+		}
+
+		var err error
+		brokenBuilders, err = listBrokenBuilders()
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+		if len(brokenBuilders) > 0 {
+			fmt.Fprintf(os.Stderr, "omitting builders with known issues:\n\t%s\n\n", strings.Join(brokenBuilders, "\n\t"))
+		}
+
+	}
+
 	status := 1
 	defer func() { os.Exit(status) }()
 
@@ -169,6 +194,11 @@ var pathDateRE = regexp.MustCompile(`^(\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2})-([0-
 func process(path, nicePath string) (found bool, err error) {
 	// If this is from the dashboard, filter by builder and date and get the builder URL.
 	builder := filepath.Base(nicePath)
+	for _, b := range brokenBuilders {
+		if builder == b {
+			return false, nil
+		}
+	}
 	if omit.AnyMatchString(builder) {
 		return false, nil
 	}