Fix behaviour for single non-root go.mod

Also add telemetry so we can prioritise future work on the autobuilder.

go/extractor/cli/go-autobuilder/go-autobuilder.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"sort"
 	"strings"
 
 	"golang.org/x/mod/semver"
@@ -240,28 +241,109 @@ func getSourceDir() string {
 	return srcdir
 }
 
+func getDirs(paths []string) []string {
+	dirs := make([]string, len(paths))
+	for i, path := range paths {
+		dirs[i] = filepath.Dir(path)
+	}
+	return dirs
+}
+
+// Note this has the side effect of sorting `dirs`
+func checkDirsNested(dirs []string) bool {
+	// the paths were generated by a depth-first search so I think they might
+	// be sorted, but we sort them just in case
+	sort.Strings(dirs)
+	for _, dir := range dirs {
+		if !strings.HasPrefix(dir, dirs[0]) {
+			return false
+		}
+	}
+	return true
+}
+
+func findGoModFiles(emitDiagnostics bool) (string, bool) {
+	goModPaths := util.FindAllFilesWithName(".", "go.mod", "vendor")
+	if len(goModPaths) == 0 {
+		// preserve current behaviour
+		return ".", false
+	}
+	goModDirs := getDirs(goModPaths)
+	if util.AnyGoFilesOutsideDirs(".", goModDirs...) {
+		if emitDiagnostics {
+			diagnostics.EmitGoFilesOutsideGoModules(goModPaths)
+		}
+		// preserve current behaviour
+		return ".", true
+	}
+	if len(goModPaths) > 1 {
+		// currently not supported
+		if emitDiagnostics {
+			if checkDirsNested(goModDirs) {
+				diagnostics.EmitMultipleGoModFoundNested(goModPaths)
+			} else {
+				diagnostics.EmitMultipleGoModFoundNotNested(goModPaths)
+			}
+		}
+		// preserve current behaviour
+		return ".", true
+	}
+	if emitDiagnostics {
+		if goModDirs[0] == "." {
+			diagnostics.EmitSingleRootGoModFound(goModPaths[0])
+		} else {
+			diagnostics.EmitSingleNonRootGoModFound(goModPaths[0])
+		}
+	}
+	return goModDirs[0], true
+}
+
 // Returns the appropriate DependencyInstallerMode for the current project
-func getDepMode() DependencyInstallerMode {
-	if util.FileExists("go.mod") {
+func getDepMode(emitDiagnostics bool) (DependencyInstallerMode, string) {
+	if util.FileExists("BUILD") {
+		// currently not supported
+		if emitDiagnostics {
+			diagnostics.EmitBazelBuildFileFound()
+		}
+	}
+
+	goWorkPaths := util.FindAllFilesWithName(".", "go.work", "vendor")
+	if len(goWorkPaths) > 0 {
+		// currently not supported
+		if emitDiagnostics {
+			diagnostics.EmitGoWorkFound(goWorkPaths)
+		}
+	}
+
+	baseDir, goModFound := findGoModFiles(emitDiagnostics)
+	if goModFound {
 		log.Println("Found go.mod, enabling go modules")
-		return GoGetWithModules
+		return GoGetWithModules, baseDir
 	}
+
 	if util.FileExists("Gopkg.toml") {
+		if emitDiagnostics {
+			diagnostics.EmitGopkgTomlFound()
+		}
 		log.Println("Found Gopkg.toml, using dep instead of go get")
-		return Dep
+		return Dep, "."
 	}
+
 	if util.FileExists("glide.yaml") {
+		if emitDiagnostics {
+			diagnostics.EmitGlideYamlFound()
+		}
 		log.Println("Found glide.yaml, using Glide instead of go get")
-		return Glide
+		return Glide, "."
 	}
-	return GoGetNoModules
+	return GoGetNoModules, "."
 }
 
 // Tries to open `go.mod` and read a go directive, returning the version and whether it was found.
-func tryReadGoDirective(depMode DependencyInstallerMode) (string, bool) {
+func tryReadGoDirective(depMode DependencyInstallerMode, baseDir string) (string, bool) {
 	if depMode == GoGetWithModules {
 		versionRe := regexp.MustCompile(`(?m)^go[ \t\r]+([0-9]+\.[0-9]+)$`)
-		goMod, err := os.ReadFile("go.mod")
+		goMod, err := os.ReadFile(filepath.Join(baseDir, "go.mod"))
 		if err != nil {
 			log.Println("Failed to read go.mod to check for missing Go version")
 		} else {
@@ -277,13 +359,13 @@ func tryReadGoDirective(depMode DependencyInstallerMode) (string, bool) {
 }
 
 // Returns the appropriate ModMode for the current project
-func getModMode(depMode DependencyInstallerMode) ModMode {
+func getModMode(depMode DependencyInstallerMode, baseDir string) ModMode {
 	if depMode == GoGetWithModules {
 		// if a vendor/modules.txt file exists, we assume that there are vendored Go dependencies, and
 		// skip the dependency installation step and run the extractor with `-mod=vendor`
-		if util.FileExists("vendor/modules.txt") {
+		if util.FileExists(baseDir + "/vendor/modules.txt") {
 			return ModVendor
-		} else if util.DirExists("vendor") {
+		} else if util.DirExists(baseDir + "/vendor") {
 			return ModMod
 		}
 	}
@@ -344,25 +426,29 @@ func getNeedGopath(depMode DependencyInstallerMode, importpath string) bool {
 }
 
 // Try to update `go.mod` and `go.sum` if the go version is >= 1.16.
-func tryUpdateGoModAndGoSum(modMode ModMode, depMode DependencyInstallerMode) {
+func tryUpdateGoModAndGoSum(modMode ModMode, depMode DependencyInstallerMode, baseDir string) {
 	// Go 1.16 and later won't automatically attempt to update go.mod / go.sum during package loading, so try to update them here:
 	if modMode != ModVendor && depMode == GoGetWithModules && semver.Compare(getEnvGoSemVer(), "v1.16") >= 0 {
 		// stat go.mod and go.sum
-		beforeGoModFileInfo, beforeGoModErr := os.Stat("go.mod")
+		goModPath := filepath.Join(baseDir, "go.mod")
+		beforeGoModFileInfo, beforeGoModErr := os.Stat(goModPath)
 		if beforeGoModErr != nil {
 			log.Println("Failed to stat go.mod before running `go mod tidy -e`")
 		}
 
-		beforeGoSumFileInfo, beforeGoSumErr := os.Stat("go.sum")
+		goSumPath := filepath.Join(baseDir, "go.sum")
+		beforeGoSumFileInfo, beforeGoSumErr := os.Stat(goSumPath)
 
 		// run `go mod tidy -e`
-		res := util.RunCmd(exec.Command("go", "mod", "tidy", "-e"))
+		cmd := exec.Command("go", "mod", "tidy", "-e")
+		cmd.Dir = baseDir
+		res := util.RunCmd(cmd)
 
 		if !res {
 			log.Println("Failed to run `go mod tidy -e`")
 		} else {
 			if beforeGoModFileInfo != nil {
-				afterGoModFileInfo, afterGoModErr := os.Stat("go.mod")
+				afterGoModFileInfo, afterGoModErr := os.Stat(goModPath)
 				if afterGoModErr != nil {
 					log.Println("Failed to stat go.mod after running `go mod tidy -e`")
 				} else if afterGoModFileInfo.ModTime().After(beforeGoModFileInfo.ModTime()) {
@@ -371,7 +457,7 @@ func tryUpdateGoModAndGoSum(modMode ModMode, depMode DependencyInstallerMode) {
 				}
 			}
 
-			afterGoSumFileInfo, afterGoSumErr := os.Stat("go.sum")
+			afterGoSumFileInfo, afterGoSumErr := os.Stat(goSumPath)
 			if afterGoSumErr != nil {
 				log.Println("Failed to stat go.sum after running `go mod tidy -e`")
 			} else {
@@ -560,7 +646,7 @@ func buildWithCustomCommands(inst string) {
 }
 
 // Install dependencies using the given dependency installer mode.
-func installDependencies(depMode DependencyInstallerMode) {
+func installDependencies(depMode DependencyInstallerMode, baseDir string) {
 	// automatically determine command to install dependencies
 	var install *exec.Cmd
 	if depMode == Dep {
@@ -606,31 +692,28 @@ func installDependencies(depMode DependencyInstallerMode) {
 
 		// get dependencies
 		install = exec.Command("go", "get", "-v", "./...")
-		log.Println("Installing dependencies using `go get -v ./...`.")
+		install.Dir = baseDir
+		log.Printf("Installing dependencies using `go get -v ./...` in `%s`.\n", baseDir)
 	}
 	util.RunCmd(install)
 }
 
 // Run the extractor.
-func extract(depMode DependencyInstallerMode, modMode ModMode) {
+func extract(depMode DependencyInstallerMode, modMode ModMode, baseDir string) {
 	extractor, err := util.GetExtractorPath()
 	if err != nil {
 		log.Fatalf("Could not determine path of extractor: %v.\n", err)
 	}
 
-	cwd, err := os.Getwd()
-	if err != nil {
-		log.Fatalf("Unable to determine current directory: %s\n", err.Error())
-	}
-
 	extractorArgs := []string{}
 	if depMode == GoGetWithModules {
 		extractorArgs = append(extractorArgs, modMode.argsForGoVersion(getEnvGoSemVer())...)
 	}
 	extractorArgs = append(extractorArgs, "./...")
 
-	log.Printf("Running extractor command '%s %v' from directory '%s'.\n", extractor, extractorArgs, cwd)
+	log.Printf("Running extractor command '%s %v' from directory '%s'.\n", extractor, extractorArgs, baseDir)
 	cmd := exec.Command(extractor, extractorArgs...)
+	cmd.Dir = baseDir
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 	err = cmd.Run()
@@ -650,21 +733,21 @@ func installDependenciesAndBuild() {
 
 	// determine how to install dependencies and whether a GOPATH needs to be set up before
 	// extraction
-	depMode := getDepMode()
+	depMode, baseDir := getDepMode(true)
 	if _, present := os.LookupEnv("GO111MODULE"); !present {
 		os.Setenv("GO111MODULE", "auto")
 	}
 
-	goModVersion, goModVersionFound := tryReadGoDirective(depMode)
+	goModVersion, goModVersionFound := tryReadGoDirective(depMode, baseDir)
 
 	if semver.Compare("v"+goModVersion, getEnvGoSemVer()) >= 0 {
 		diagnostics.EmitNewerGoVersionNeeded()
 	}
 
-	modMode := getModMode(depMode)
+	modMode := getModMode(depMode, baseDir)
 	modMode = fixGoVendorIssues(modMode, depMode, goModVersionFound)
 
-	tryUpdateGoModAndGoSum(modMode, depMode)
+	tryUpdateGoModAndGoSum(modMode, depMode, baseDir)
 
 	importpath := getImportPath()
 	needGopath := getNeedGopath(depMode, importpath)
@@ -707,11 +790,11 @@ func installDependenciesAndBuild() {
 		if modMode == ModVendor {
 			log.Printf("Skipping dependency installation because a Go vendor directory was found.")
 		} else {
-			installDependencies(depMode)
+			installDependencies(depMode, baseDir)
 		}
 	}
 
-	extract(depMode, modMode)
+	extract(depMode, modMode, baseDir)
 }
 
 const minGoVersion = "1.11"
@@ -976,8 +1059,8 @@ func isGoInstalled() bool {
 // Get the version of Go to install and output it to stdout as json.
 func identifyEnvironment() {
 	var v versionInfo
-	depMode := getDepMode()
-	v.goModVersion, v.goModVersionFound = tryReadGoDirective(depMode)
+	depMode, baseDir := getDepMode(false)
+	v.goModVersion, v.goModVersionFound = tryReadGoDirective(depMode, baseDir)
 
 	v.goEnvVersionFound = isGoInstalled()
 	if v.goEnvVersionFound {