feat: add support for .gitignore

MODULE.bazel

@@ -42,6 +42,7 @@ use_repo(
     "com_github_bazelbuild_buildtools",
     "com_github_bmatcuk_doublestar_v4",
     "com_github_fsnotify_fsnotify",
+    "com_github_go_git_go_git_v5",
     "com_github_google_go_cmp",
     "com_github_pmezard_go_difflib",
     "org_golang_x_mod",

WORKSPACE

@@ -101,6 +101,7 @@ register_unittest_toolchains()
 # gazelle:repository go_repository name=com_github_client9_misspell importpath=github.com/client9/misspell
 # gazelle:repository go_repository name=com_github_envoyproxy_go_control_plane importpath=github.com/envoyproxy/go-control-plane
 # gazelle:repository go_repository name=com_github_envoyproxy_protoc_gen_validate importpath=github.com/envoyproxy/protoc-gen-validate
+# gazelle:repository go_repository name=com_github_go_git_go_git_v5 importpath=github.com/go-git/go-git/v5
 # gazelle:repository go_repository name=com_github_fsnotify_fsnotify importpath=github.com/fsnotify/fsnotify
 # gazelle:repository go_repository name=com_github_gogo_protobuf importpath=github.com/gogo/protobuf
 # gazelle:repository go_repository name=com_github_golang_glog importpath=github.com/golang/glog

deps.bzl

@@ -187,6 +187,13 @@ def gazelle_dependencies(
         sum = "h1:EQciDnbrYxy13PgWoY8AqoxGiPrpgBZ1R8UNe3ddc+A=",
         version = "v0.1.0",
     )
+    _maybe(
+        go_repository,
+        name = "com_github_go_git_go_git_v5",
+        importpath = "github.com/go-git/go-git/v5",
+        sum = "h1:7Md+ndsjrzZxbddRDZjF14qK+NN56sy6wkqaVrjZtys=",
+        version = "v5.12.0",
+    )
     _maybe(
         go_repository,
         name = "com_github_fsnotify_fsnotify",

go.mod

@@ -1,12 +1,15 @@
 module github.com/bazelbuild/bazel-gazelle
 
-go 1.21
+go 1.21.1
+
+toolchain go1.22.4
 
 require (
 	github.com/bazelbuild/buildtools v0.0.0-20240313121412-66c605173954
 	github.com/bazelbuild/rules_go v0.46.0
 	github.com/bmatcuk/doublestar/v4 v4.6.1
 	github.com/fsnotify/fsnotify v1.7.0
+	github.com/go-git/go-git/v5 v5.12.0
 	github.com/google/go-cmp v0.6.0
 	github.com/pmezard/go-difflib v1.0.0
 	golang.org/x/mod v0.16.0

go.sum

@@ -15,6 +15,8 @@ github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.m
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/fsnotify/fsnotify v1.7.0 h1:8JEhPFa5W2WU7YfeZzPNqzMP6Lwt7L2715Ggo0nosvA=
 github.com/fsnotify/fsnotify v1.7.0/go.mod h1:40Bi/Hjc2AVfZrqy+aj+yEI+/bRxZnMJyTJwOpGvigM=
+github.com/go-git/go-git/v5 v5.12.0 h1:7Md+ndsjrzZxbddRDZjF14qK+NN56sy6wkqaVrjZtys=
+github.com/go-git/go-git/v5 v5.12.0/go.mod h1:FTM9VKtnI2m65hNI/TenDDDnUf2Q9FHnXYjuz9i5OEY=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=

vendor/modules.txt

@@ -4,6 +4,7 @@ github.com/bazelbuild/buildtools/build
 github.com/bazelbuild/buildtools/tables
 # github.com/bazelbuild/rules_go v0.46.0
 ## explicit; go 1.21.1
+github.com/bazelbuild/rules_go/go/runfiles
 github.com/bazelbuild/rules_go/go/tools/bazel
 github.com/bazelbuild/rules_go/go/tools/bazel_testing
 github.com/bazelbuild/rules_go/go/tools/internal/txtar
@@ -13,6 +14,8 @@ github.com/bmatcuk/doublestar/v4
 # github.com/fsnotify/fsnotify v1.7.0
 ## explicit; go 1.17
 github.com/fsnotify/fsnotify
+# github.com/go-git/go-git/v5 v5.12.0
+## explicit; go 1.19
 # github.com/google/go-cmp v0.6.0
 ## explicit; go 1.13
 github.com/google/go-cmp/cmp

walk/BUILD.bazel

@@ -13,6 +13,7 @@ go_library(
         "//flag",
         "//rule",
         "@com_github_bmatcuk_doublestar_v4//:doublestar",
+        "@com_github_go_git_go_git_v5//plumbing/format/gitignore",
     ],
 )
 

walk/config.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"io"
 	"io/fs"
 	"log"
 	"os"
@@ -29,6 +30,7 @@ import (
 	"github.com/bazelbuild/bazel-gazelle/config"
 	"github.com/bazelbuild/bazel-gazelle/rule"
 	"github.com/bmatcuk/doublestar/v4"
+	"github.com/go-git/go-git/v5/plumbing/format/gitignore"
 
 	gzflag "github.com/bazelbuild/bazel-gazelle/flag"
 )
@@ -41,6 +43,9 @@ type walkConfig struct {
 	excludes []string
 	ignore   bool
 	follow   []string
+
+	gitignoreEnabled bool
+	gitignore        *gitignoreEntry
 }
 
 const walkName = "_walk"
@@ -56,6 +61,17 @@ func (wc *walkConfig) isExcluded(rel, base string) bool {
 	return matchAnyGlob(wc.excludes, path.Join(rel, base))
 }
 
+func (wc *walkConfig) isGitIgnored(rel, base string) bool {
+	// .gitignore
+	if wc.gitignoreEnabled && wc.gitignore != nil {
+		if wc.gitignore.isIgnored(strings.Split(path.Join(rel, base), "/")) {
+			return true
+		}
+	}
+
+	return false
+}
+
 func (wc *walkConfig) shouldFollow(rel, base string) bool {
 	return matchAnyGlob(wc.follow, path.Join(rel, base))
 }
@@ -73,7 +89,7 @@ func (*Configurer) RegisterFlags(fs *flag.FlagSet, cmd string, c *config.Config)
 func (*Configurer) CheckFlags(fs *flag.FlagSet, c *config.Config) error { return nil }
 
 func (*Configurer) KnownDirectives() []string {
-	return []string{"exclude", "follow", "ignore"}
+	return []string{"gitignore", "exclude", "follow", "ignore"}
 }
 
 func (cr *Configurer) Configure(c *config.Config, rel string, f *rule.File) {
@@ -99,11 +115,26 @@ func (cr *Configurer) Configure(c *config.Config, rel string, f *rule.File) {
 				wcCopy.follow = append(wcCopy.follow, path.Join(rel, d.Value))
 			case "ignore":
 				wcCopy.ignore = true
+			case "gitignore":
+				wcCopy.gitignoreEnabled = d.Value == "on"
 			}
 		}
 	}
 
 	c.Exts[walkName] = wcCopy
+
+	// TODO: read the gitignore file even if gitignoring is not enabled in this dir
+	// because it might be enabled in a subdir.
+	if wcCopy.gitignoreEnabled {
+		// Collect gitignore style ignore files in this directory.
+		ignoreFilePath := path.Join(c.RepoRoot, rel, ".gitignore")
+
+		// TODO: reuse the fs entry already created by gazelle to avoid os.Open,
+		// see https://github.com/bazelbuild/bazel-gazelle/pull/1737.
+		if ignoreReader, ignoreErr := os.Open(ignoreFilePath); ignoreErr == nil {
+			wcCopy.gitignore = createGitIgnorer(wcCopy.gitignore, rel, ignoreReader)
+		}
+	}
 }
 
 type isIgnoredFunc = func(string) bool
@@ -151,6 +182,47 @@ func loadBazelIgnore(repoRoot string) (isIgnoredFunc, error) {
 	return isIgnored, nil
 }
 
+type gitignoreEntry struct {
+	i      *gitignore.Matcher
+	base   string
+	parent *gitignoreEntry
+}
+
+func createGitIgnorer(parent *gitignoreEntry, rel string, ignoreReader io.Reader) *gitignoreEntry {
+	domain := []string{}
+	if rel != "" {
+		domain = strings.Split(rel, "/")
+	}
+
+	matcherPatterns := make([]gitignore.Pattern, 0)
+
+	reader := bufio.NewScanner(ignoreReader)
+	for reader.Scan() {
+		p := gitignore.ParsePattern(reader.Text(), domain)
+		matcherPatterns = append(matcherPatterns, p)
+	}
+
+	ignore := gitignore.NewMatcher(matcherPatterns)
+
+	return &gitignoreEntry{
+		i:      ignore,
+		base:   rel,
+		parent: parent,
+	}
+}
+
+func (g *gitignoreEntry) isIgnored(p []string) bool {
+	if g.i.Match(p) {
+		return true
+	}
+
+	if g.parent == nil {
+		return false
+	}
+
+	return g.parent.isIgnored(p)
+}
+
 func checkPathMatchPattern(pattern string) error {
 	_, err := doublestar.Match(pattern, "x")
 	return err

walk/walk.go

@@ -155,14 +155,14 @@ func visit(c *config.Config, cexts []config.Configurer, isBazelIgnored isIgnored
 	c = configure(cexts, knownDirectives, c, rel, f)
 	wc := getWalkConfig(c)
 
-	if wc.isExcluded(rel, ".") {
+	if wc.isExcluded(rel, ".") || wc.isGitIgnored(rel, ".") {
 		return
 	}
 
 	var subdirs, regularFiles []string
 	for _, ent := range ents {
 		base := ent.Name()
-		if isBazelIgnored(path.Join(rel, base)) || wc.isExcluded(rel, base) {
+		if isBazelIgnored(path.Join(rel, base)) || wc.isExcluded(rel, base) || wc.isGitIgnored(rel, base) {
 			continue
 		}
 		ent := resolveFileInfo(wc, dir, rel, ent)