build: run 'go mod tidy' check as part of lint

build/ci.go

@@ -349,10 +349,10 @@ func downloadSpecTestFixtures(csdb *build.ChecksumDB, cachedir string) string {
 	return filepath.Join(cachedir, base)
 }
 
-// hashSourceFiles iterates all files under the top-level project directory
+// hashAllSourceFiles iterates all files under the top-level project directory
 // computing the hash of each file (excluding files within the tests
 // subrepo)
-func hashSourceFiles() (map[string]common.Hash, error) {
+func hashAllSourceFiles() (map[string]common.Hash, error) {
 	res := make(map[string]common.Hash)
 	err := filepath.WalkDir(".", func(path string, d os.DirEntry, err error) error {
 		if strings.HasPrefix(path, filepath.FromSlash("tests/testdata")) {
@@ -379,6 +379,56 @@ func hashSourceFiles() (map[string]common.Hash, error) {
 	return res, nil
 }
 
+// hashSourceFiles iterates the provided set of filepaths (relative to the top-level geth project directory)
+// computing the hash of each file.
+func hashSourceFiles(files []string) (map[string]common.Hash, error) {
+	res := make(map[string]common.Hash)
+	for _, filePath := range files {
+		f, err := os.OpenFile(filePath, os.O_RDONLY, 0666)
+		if err != nil {
+			return nil, err
+		}
+		hasher := sha256.New()
+		if _, err := io.Copy(hasher, f); err != nil {
+			return nil, err
+		}
+		res[filePath] = common.Hash(hasher.Sum(nil))
+	}
+	return res, nil
+}
+
+// compareHashedFilesets compares two maps (key is relative file path to top-level geth directory, value is its hash)
+// and returns the list of file paths whose hashes differed.
+func compareHashedFilesets(preHashes map[string]common.Hash, postHashes map[string]common.Hash) []string {
+	updates := []string{}
+	for path, postHash := range postHashes {
+		preHash, ok := preHashes[path]
+		if !ok || preHash != postHash {
+			updates = append(updates, path)
+		}
+	}
+	return updates
+}
+
+func doGoModTidy() {
+	targetFiles := []string{"go.mod", "go.sum"}
+	preHashes, err := hashSourceFiles(targetFiles)
+	if err != nil {
+		log.Fatal("failed to hash go.mod/go.sum", "err", err)
+	}
+	tc := new(build.GoToolchain)
+	c := tc.Go("mod", "tidy")
+	build.MustRun(c)
+	postHashes, err := hashSourceFiles(targetFiles)
+	updates := compareHashedFilesets(preHashes, postHashes)
+	for _, updatedFile := range updates {
+		fmt.Fprintf(os.Stderr, "changed file %s\n", updatedFile)
+	}
+	if len(updates) != 0 {
+		log.Fatal("go.sum and/or go.mod were updated by running 'go mod tidy'")
+	}
+}
+
 // doGenerate ensures that re-generating generated files does not cause
 // any mutations in the source file tree:  i.e. all generated files were
 // updated and committed.  Any stale generated files are updated.
@@ -395,7 +445,7 @@ func doGenerate() {
 	var preHashes map[string]common.Hash
 	if *verify {
 		var err error
-		preHashes, err = hashSourceFiles()
+		preHashes, err = hashAllSourceFiles()
 		if err != nil {
 			log.Fatal("failed to compute map of source hashes", "err", err)
 		}
@@ -410,17 +460,11 @@ func doGenerate() {
 		return
 	}
 	// Check if files were changed.
-	postHashes, err := hashSourceFiles()
+	postHashes, err := hashAllSourceFiles()
 	if err != nil {
 		log.Fatal("error computing source tree file hashes", "err", err)
 	}
-	updates := []string{}
-	for path, postHash := range postHashes {
-		preHash, ok := preHashes[path]
-		if !ok || preHash != postHash {
-			updates = append(updates, path)
-		}
-	}
+	updates := compareHashedFilesets(preHashes, postHashes)
 	for _, updatedFile := range updates {
 		fmt.Fprintf(os.Stderr, "changed file %s\n", updatedFile)
 	}
@@ -443,6 +487,8 @@ func doLint(cmdline []string) {
 	linter := downloadLinter(*cachedir)
 	lflags := []string{"run", "--config", ".golangci.yml"}
 	build.MustRunCommandWithOutput(linter, append(lflags, packages...)...)
+
+	doGoModTidy()
 	fmt.Println("You have achieved perfection.")
 }