From 4213c203626a3f57e99eb178cfdd3e753ad34687 Mon Sep 17 00:00:00 2001
From: Andrew Z Allen <me@andrewzallen.com>
Date: Tue, 26 May 2020 23:36:33 -0600
Subject: [PATCH 1/9] Create Gazelle language for Starlark

---
 BUILD                                         |  25 ++
 WORKSPACE                                     |  35 +++
 gazelle/BUILD                                 |  51 ++++
 gazelle/README.md                             |  13 +
 gazelle/gazelle.go                            | 263 ++++++++++++++++++
 gazelle/gazelle_test.go                       | 129 +++++++++
 gazelle/testdata/README.md                    |  52 ++++
 gazelle/testdata/defaultvisibility/BUILD.in   |   0
 gazelle/testdata/defaultvisibility/BUILD.out  |   6 +
 gazelle/testdata/defaultvisibility/WORKSPACE  |   0
 gazelle/testdata/defaultvisibility/foo.bzl    |   1 +
 .../defaultvisibility/nested/dir/BUILD.in     |   1 +
 .../defaultvisibility/nested/dir/BUILD.out    |   7 +
 .../defaultvisibility/nested/dir/bar.bzl      |   2 +
 gazelle/testdata/external/BUILD.in            |   6 +
 gazelle/testdata/external/BUILD.out           |  13 +
 gazelle/testdata/external/WORKSPACE           |   0
 gazelle/testdata/external/foo.bzl             |   1 +
 gazelle/testdata/import/BUILD.in              |   0
 gazelle/testdata/import/BUILD.out             |  12 +
 gazelle/testdata/import/WORKSPACE             |   0
 gazelle/testdata/import/bar.bzl               |   2 +
 gazelle/testdata/import/foo.bzl               |   1 +
 gazelle/testdata/multidir/BUILD.in            |   0
 gazelle/testdata/multidir/BUILD.out           |   6 +
 gazelle/testdata/multidir/WORKSPACE           |   0
 gazelle/testdata/multidir/foo.bzl             |   1 +
 .../testdata/multidir/nested/dir/BUILD.out    |   6 +
 gazelle/testdata/multidir/nested/dir/bar.bzl  |   2 +
 gazelle/testdata/nobuildfiles/BUILD.out       |   5 +
 gazelle/testdata/nobuildfiles/WORKSPACE       |   0
 gazelle/testdata/nobuildfiles/foo.bzl         |   0
 gazelle/testdata/private/BUILD.in             |   0
 gazelle/testdata/private/BUILD.out            |   6 +
 gazelle/testdata/private/WORKSPACE            |   0
 gazelle/testdata/private/foo.bzl              |   1 +
 .../testdata/private/nested/private/BUILD.out |   5 +
 .../testdata/private/nested/private/bar.bzl   |   2 +
 gazelle/testdata/simple/BUILD.in              |   6 +
 gazelle/testdata/simple/BUILD.out             |  12 +
 gazelle/testdata/simple/WORKSPACE             |   0
 gazelle/testdata/simple/foo.bzl               |   0
 gazelle/testdata/tests/BUILD.in               |   6 +
 gazelle/testdata/tests/BUILD.out              |  12 +
 gazelle/testdata/tests/WORKSPACE              |   0
 gazelle/testdata/tests/foo.bzl                |   0
 gazelle/testdata/tests/foo_tests.bzl          |   0
 lib/BUILD                                     |   5 +
 rules/BUILD                                   |   5 +
 49 files changed, 700 insertions(+)
 create mode 100644 gazelle/BUILD
 create mode 100644 gazelle/README.md
 create mode 100644 gazelle/gazelle.go
 create mode 100644 gazelle/gazelle_test.go
 create mode 100644 gazelle/testdata/README.md
 create mode 100644 gazelle/testdata/defaultvisibility/BUILD.in
 create mode 100644 gazelle/testdata/defaultvisibility/BUILD.out
 create mode 100644 gazelle/testdata/defaultvisibility/WORKSPACE
 create mode 100644 gazelle/testdata/defaultvisibility/foo.bzl
 create mode 100644 gazelle/testdata/defaultvisibility/nested/dir/BUILD.in
 create mode 100644 gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
 create mode 100644 gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
 create mode 100644 gazelle/testdata/external/BUILD.in
 create mode 100644 gazelle/testdata/external/BUILD.out
 create mode 100644 gazelle/testdata/external/WORKSPACE
 create mode 100644 gazelle/testdata/external/foo.bzl
 create mode 100644 gazelle/testdata/import/BUILD.in
 create mode 100644 gazelle/testdata/import/BUILD.out
 create mode 100644 gazelle/testdata/import/WORKSPACE
 create mode 100644 gazelle/testdata/import/bar.bzl
 create mode 100644 gazelle/testdata/import/foo.bzl
 create mode 100644 gazelle/testdata/multidir/BUILD.in
 create mode 100644 gazelle/testdata/multidir/BUILD.out
 create mode 100644 gazelle/testdata/multidir/WORKSPACE
 create mode 100644 gazelle/testdata/multidir/foo.bzl
 create mode 100644 gazelle/testdata/multidir/nested/dir/BUILD.out
 create mode 100644 gazelle/testdata/multidir/nested/dir/bar.bzl
 create mode 100644 gazelle/testdata/nobuildfiles/BUILD.out
 create mode 100644 gazelle/testdata/nobuildfiles/WORKSPACE
 create mode 100644 gazelle/testdata/nobuildfiles/foo.bzl
 create mode 100644 gazelle/testdata/private/BUILD.in
 create mode 100644 gazelle/testdata/private/BUILD.out
 create mode 100644 gazelle/testdata/private/WORKSPACE
 create mode 100644 gazelle/testdata/private/foo.bzl
 create mode 100644 gazelle/testdata/private/nested/private/BUILD.out
 create mode 100644 gazelle/testdata/private/nested/private/bar.bzl
 create mode 100644 gazelle/testdata/simple/BUILD.in
 create mode 100644 gazelle/testdata/simple/BUILD.out
 create mode 100644 gazelle/testdata/simple/WORKSPACE
 create mode 100644 gazelle/testdata/simple/foo.bzl
 create mode 100644 gazelle/testdata/tests/BUILD.in
 create mode 100644 gazelle/testdata/tests/BUILD.out
 create mode 100644 gazelle/testdata/tests/WORKSPACE
 create mode 100644 gazelle/testdata/tests/foo.bzl
 create mode 100644 gazelle/testdata/tests/foo_tests.bzl

diff --git a/BUILD b/BUILD
index c0ccdcd6..ec378c67 100644
--- a/BUILD
+++ b/BUILD
@@ -4,6 +4,10 @@ licenses(["notice"])
 
 package(default_visibility = ["//visibility:public"])
 
+# gazelle:exclude internal_deps.bzl
+# gazelle:exclude internal_setup.bzl
+# gazelle:exclude skylark_library.bzl
+
 exports_files(["LICENSE"])
 
 filegroup(
@@ -45,6 +49,16 @@ bzl_library(
     srcs = ["bzl_library.bzl"],
 )
 
+bzl_library(
+    name = "version",
+    srcs = ["version.bzl"],
+)
+
+bzl_library(
+    name = "workspace",
+    srcs = ["workspace.bzl"],
+)
+
 # The files needed for distribution.
 # TODO(aiuto): We should strip this from the release, but there is no
 # capability now to generate BUILD.foo from BUILD and have it appear in the
@@ -69,3 +83,14 @@ filegroup(
         "//rules:bins",
     ],
 )
+
+# Below this line is for development purposes only and should thus not be
+# included by dependencies on bazel-skylib nor packaged in the distribution
+# release.
+
+load("@bazel_gazelle//:def.bzl", "gazelle")
+
+gazelle(
+    name = "gazelle",
+    gazelle = "//gazelle:gazelle-skylib",
+)
diff --git a/WORKSPACE b/WORKSPACE
index a6581ec6..cefdfa0a 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -40,3 +40,38 @@ maybe(
         "https://github.com/bazelbuild/rules_cc/archive/cb2dfba6746bfa3c3705185981f3109f0ae1b893.zip",
     ],
 )
+
+# Below are dependencies for the generator.
+
+load("@bazel_federation//:repositories.bzl", "rules_go")
+
+rules_go()
+# Provide a repository hint for Gazelle to inform it that the go package
+# github.com/bazelbuild/rules_go is available from io_bazel_rules_go and it
+# doesn't need to duplicatively fetch it.
+# gazelle:repository go_repository name=io_bazel_rules_go importpath=github.com/bazelbuild/rules_go
+
+load("@bazel_federation//setup:rules_go.bzl", "rules_go_setup")
+
+rules_go_setup()
+
+http_archive(
+    name = "bazel_gazelle",
+    sha256 = "bfd86b3cbe855d6c16c6fce60d76bd51f5c8dbc9cfcaef7a2bb5c1aafd0710e8",
+    urls = [
+        "https://mirror.bazel.build/github.com/bazelbuild/bazel-gazelle/releases/download/v0.21.0/bazel-gazelle-v0.21.0.tar.gz",
+        "https://github.com/bazelbuild/bazel-gazelle/releases/download/v0.21.0/bazel-gazelle-v0.21.0.tar.gz",
+    ],
+)
+# Another Gazelle repository hint.
+# gazelle:repository go_repository name=bazel_gazelle importpath=github.com/bazelbuild/bazel-gazelle/testtools
+
+load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
+
+gazelle_dependencies()
+
+go_repository(
+    name = "net_starlark_go",
+    commit = "0aa95694c76801c1528349fb86033b9098d634fc",
+    importpath = "go.starlark.net",
+)
diff --git a/gazelle/BUILD b/gazelle/BUILD
new file mode 100644
index 00000000..ca23dcf3
--- /dev/null
+++ b/gazelle/BUILD
@@ -0,0 +1,51 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+load("@bazel_gazelle//:def.bzl", "DEFAULT_LANGUAGES", "gazelle_binary")
+
+# gazelle:exclude testdata
+
+go_library(
+    name = "go_default_library",
+    srcs = ["gazelle.go"],
+    importpath = "github.com/bazelbuild/bazel-skylib/gazelle",
+    visibility = ["//visibility:public"],
+    deps = [
+        "@bazel_gazelle//config:go_default_library",
+        "@bazel_gazelle//label:go_default_library",
+        "@bazel_gazelle//language:go_default_library",
+        "@bazel_gazelle//repo:go_default_library",
+        "@bazel_gazelle//resolve:go_default_library",
+        "@bazel_gazelle//rule:go_default_library",
+        "@net_starlark_go//syntax:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["gazelle_test.go"],
+    data = [
+        ":gazelle-skylib",
+    ] + glob([
+        "testdata/**",
+    ]),
+    embed = [":go_default_library"],
+    deps = [
+        "@bazel_gazelle//testtools:go_default_library",
+        "@io_bazel_rules_go//go/tools/bazel:go_default_library",
+    ],
+)
+
+# This gazelle binary is used exclusively for testing the gazelle language
+# extension and thus only has the skylib language installed.
+gazelle_binary(
+    name = "gazelle-skylib",
+    languages = [":go_default_library"],
+    msan = "off",
+    pure = "off",
+    race = "off",
+    static = "off",
+    visibility = [
+        # Also make the binary available in the root of the repo for use, but
+        # not externally.
+        "//:__pkg__",
+    ],
+)
diff --git a/gazelle/README.md b/gazelle/README.md
new file mode 100644
index 00000000..8b7cb7b9
--- /dev/null
+++ b/gazelle/README.md
@@ -0,0 +1,13 @@
+# Gazelle
+
+Gazelle is a `BUILD` file generator for Bazel. This directory contains a
+language extension for the Gazelle generator that allows it to automatically
+parse valid `bzl_library` targets for all `.bzl` files in a repo in which it
+runs. It will additionally include a `deps` entry tracking every `.bzl` that is
+`load`ed into the primary file.
+
+This can be used, for example, to generate
+[`stardoc`](https://github.com/bazelbuild/stardoc) documentation for your
+`.bzl` files, both simplify the task of and improve the quality of
+documentation.
+
diff --git a/gazelle/gazelle.go b/gazelle/gazelle.go
new file mode 100644
index 00000000..9b302008
--- /dev/null
+++ b/gazelle/gazelle.go
@@ -0,0 +1,263 @@
+/* Copyright 2020 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package gazelle generates a `bzl_library` target for every `.bzl` file in
+// each package.
+//
+// The `bzl_library` rule is provided by
+// https://github.com/bazelbuild/bazel-skylib.
+//
+// This extension is experimental and subject to change. It is not included
+// in the default Gazelle binary.
+package gazelle
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"github.com/bazelbuild/bazel-gazelle/config"
+	"github.com/bazelbuild/bazel-gazelle/label"
+	"github.com/bazelbuild/bazel-gazelle/language"
+	"github.com/bazelbuild/bazel-gazelle/repo"
+	"github.com/bazelbuild/bazel-gazelle/resolve"
+	"github.com/bazelbuild/bazel-gazelle/rule"
+
+	"go.starlark.net/syntax"
+)
+
+const languageName = "starlark"
+const fileType = ".bzl"
+
+var ignoreSuffix = suffixes{
+	"_tests.bzl",
+	"_test.bzl",
+}
+
+type suffixes []string
+
+func (s suffixes) Matches(test string) bool {
+	for _, v := range s {
+		if strings.HasSuffix(test, v) {
+			return true
+		}
+	}
+	return false
+}
+
+type bzlLibraryLang struct{}
+
+// NewLanguage is called by Gazelle to install this language extension in a binary.
+func NewLanguage() language.Language {
+	return &bzlLibraryLang{}
+}
+
+// Name returns the name of the language. This should be a prefix of the
+// kinds of rules generated by the language, e.g., "go" for the Go extension
+// since it generates "go_library" rules.
+func (*bzlLibraryLang) Name() string { return languageName }
+
+// The following methods are implemented to satisfy the
+// https://pkg.go.dev/github.com/bazelbuild/bazel-gazelle/resolve?tab=doc#Resolver
+// interface, but are otherwise unused.
+func (*bzlLibraryLang) RegisterFlags(fs *flag.FlagSet, cmd string, c *config.Config) {}
+func (*bzlLibraryLang) CheckFlags(fs *flag.FlagSet, c *config.Config) error          { return nil }
+func (*bzlLibraryLang) KnownDirectives() []string                                    { return nil }
+func (*bzlLibraryLang) Configure(c *config.Config, rel string, f *rule.File)         {}
+
+// Kinds returns a map of maps rule names (kinds) and information on how to
+// match and merge attributes that may be found in rules of those kinds. All
+// kinds of rules generated for this language may be found here.
+func (*bzlLibraryLang) Kinds() map[string]rule.KindInfo {
+	return kinds
+}
+
+// Loads returns .bzl files and symbols they define. Every rule generated by
+// GenerateRules, now or in the past, should be loadable from one of these
+// files.
+func (*bzlLibraryLang) Loads() []rule.LoadInfo { return nil }
+
+// Fix repairs deprecated usage of language-specific rules in f. This is
+// called before the file is indexed. Unless c.ShouldFix is true, fixes
+// that delete or rename rules should not be performed.
+func (*bzlLibraryLang) Fix(c *config.Config, f *rule.File) {}
+
+// Imports returns a list of ImportSpecs that can be used to import the rule
+// r. This is used to populate RuleIndex.
+//
+// If nil is returned, the rule will not be indexed. If any non-nil slice is
+// returned, including an empty slice, the rule will be indexed.
+func (b *bzlLibraryLang) Imports(c *config.Config, r *rule.Rule, f *rule.File) []resolve.ImportSpec {
+	srcs := r.AttrStrings("srcs")
+	imports := make([]resolve.ImportSpec, len(srcs))
+
+	for _, src := range srcs {
+		spec := resolve.ImportSpec{
+			// Lang is the language in which the import string appears (this should
+			// match Resolver.Name).
+			Lang: languageName,
+			// Imp is an import string for the library.
+			Imp: fmt.Sprintf("//%s:%s", f.Pkg, src),
+		}
+
+		imports = append(imports, spec)
+	}
+
+	return imports
+}
+
+// Embeds returns a list of labels of rules that the given rule embeds. If
+// a rule is embedded by another importable rule of the same language, only
+// the embedding rule will be indexed. The embedding rule will inherit
+// the imports of the embedded rule.
+// Since SkyLark doesn't support embedding this should always return nil.
+func (*bzlLibraryLang) Embeds(r *rule.Rule, from label.Label) []label.Label { return nil }
+
+// Resolve translates imported libraries for a given rule into Bazel
+// dependencies. Information about imported libraries is returned for each
+// rule generated by language.GenerateRules in
+// language.GenerateResult.Imports. Resolve generates a "deps" attribute (or
+// the appropriate language-specific equivalent) for each import according to
+// language-specific rules and heuristics.
+func (*bzlLibraryLang) Resolve(c *config.Config, ix *resolve.RuleIndex, rc *repo.RemoteCache, r *rule.Rule, importsRaw interface{}, from label.Label) {
+	imports := importsRaw.([]string)
+
+	r.DelAttr("deps")
+
+	if len(imports) == 0 {
+		return
+	}
+
+	deps := make([]string, 0, len(imports))
+	for _, imp := range imports {
+		if strings.HasPrefix(imp, "@") {
+			// This is a dependency that is external to the current repo.
+			deps = append(deps, strings.TrimSuffix(imp, fileType))
+		} else {
+			res := resolve.ImportSpec{
+				Lang: languageName,
+				Imp:  imp,
+			}
+			matches := ix.FindRulesByImport(res, languageName)
+			fmt.Printf("ix: %v\n", ix)
+
+			if len(matches) == 0 {
+				fmt.Printf("Didn't find match for %q\n", imp)
+			}
+
+			for _, m := range matches {
+				deps = append(deps, m.Label.String())
+			}
+		}
+	}
+
+	sort.Strings(deps)
+	if len(deps) > 0 {
+		r.SetAttr("deps", deps)
+	}
+}
+
+var kinds = map[string]rule.KindInfo{
+	"bzl_library": {
+		NonEmptyAttrs:  map[string]bool{"srcs": true, "deps": true},
+		MergeableAttrs: map[string]bool{"srcs": true},
+	},
+}
+
+// GenerateRules extracts build metadata from source files in a directory.
+// GenerateRules is called in each directory where an update is requested
+// in depth-first post-order.
+//
+// args contains the arguments for GenerateRules. This is passed as a
+// struct to avoid breaking implementations in the future when new
+// fields are added.
+//
+// A GenerateResult struct is returned. Optional fields may be added to this
+// type in the future.
+//
+// Any non-fatal errors this function encounters should be logged using
+// log.Print.
+func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.GenerateResult {
+	var rules []*rule.Rule
+	var imports []interface{}
+	for _, f := range append(args.RegularFiles) {
+		if ignoreSuffix.Matches(f) {
+			continue
+		}
+		if strings.HasSuffix(f, fileType) {
+			name := strings.TrimSuffix(f, fileType)
+			r := rule.NewRule("bzl_library", name)
+
+			r.SetAttr("srcs", []string{f})
+
+			if args.File == nil || !args.File.HasDefaultVisibility() {
+				var inPrivateDir bool
+				for _, d := range strings.Split(args.Dir, string(filepath.Separator)) {
+					if d == "private" {
+						inPrivateDir = true
+					}
+				}
+				if !inPrivateDir {
+					r.SetAttr("visibility", []string{"//visibility:public"})
+				}
+			}
+
+			fullPath := filepath.Join(args.Dir, f)
+			loads, err := getBzlFileLoads(fullPath)
+			if err != nil {
+				fmt.Printf("Error getting getBzlFileLoads(%q, %q): %v", args.Dir, f, err)
+				// Don't `continue` since it is reasonable to create a target even without deps.
+			}
+			fmt.Printf("loads: %v\n", loads)
+
+			rules = append(rules, r)
+			imports = append(imports, loads)
+		}
+	}
+	return language.GenerateResult{
+		Gen:     rules,
+		Imports: imports,
+	}
+}
+
+func getBzlFileLoads(path string) ([]string, error) {
+	f, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("ioutil.ReadFile(%q) error: %v", path, err)
+	}
+	ast, err := syntax.Parse(path, f, 0644)
+	if err != nil {
+		return nil, fmt.Errorf("syntax.Parse(%q) error: %v", f, err)
+	}
+
+	var loads []string
+	syntax.Walk(ast, func(n syntax.Node) bool {
+		if l, ok := n.(*syntax.LoadStmt); ok {
+			val, ok := l.Module.Value.(string)
+			if !ok {
+				fmt.Printf("The load statement at %s:%s is not a simple string. Therefore, bazel targets can not be generated automatically for it.", path, l.Module.TokenPos)
+				return true
+			}
+			loads = append(loads, val)
+		}
+		return true
+	})
+	sort.Strings(loads)
+
+	return loads, nil
+}
diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
new file mode 100644
index 00000000..b4ced390
--- /dev/null
+++ b/gazelle/gazelle_test.go
@@ -0,0 +1,129 @@
+package gazelle
+
+/* Copyright 2020 The Bazel Authors. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+   http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/bazelbuild/bazel-gazelle/testtools"
+	"github.com/bazelbuild/rules_go/go/tools/bazel"
+)
+
+var gazellePath = findGazelle()
+
+const base = "testdata"
+
+// TestGazelleBinary runs a gazelle binary with starlib installed on each
+// directory in `testdata/*`. Please see `testdata/README.md` for more
+// information on each test.
+func TestGazelleBinary(t *testing.T) {
+	ds, err := ioutil.ReadDir(base)
+	if err != nil {
+		t.Errorf("ioutil.ReadDir(%q) error: %v", base, err)
+	}
+	for _, d := range ds {
+		if d.IsDir() {
+			t.Run(d.Name(), testPath(d.Name()))
+		}
+	}
+}
+
+func testPath(dir string) func(t *testing.T) {
+	return func(t *testing.T) {
+		var inputs []testtools.FileSpec
+		var goldens []testtools.FileSpec
+
+		if err := filepath.Walk(filepath.Join(base, dir), func(path string, info os.FileInfo, err error) error {
+			// If you were called with an error, don't try to recover, just fail.
+			if err != nil {
+				return err
+			}
+
+			// Skip dirs.
+			if info.IsDir() {
+				return nil
+			}
+
+			content, err := ioutil.ReadFile(path)
+			if err != nil {
+				return err
+			}
+
+			// Now trim the common prefix off.
+			newPath := strings.TrimPrefix(path, filepath.Join(base, dir)+"/")
+
+			if strings.HasSuffix(newPath, ".in") {
+				inputs = append(inputs, testtools.FileSpec{
+					Path:    strings.TrimSuffix(newPath, ".in"),
+					Content: string(content),
+				})
+			} else if strings.HasSuffix(newPath, ".out") {
+				goldens = append(goldens, testtools.FileSpec{
+					Path:    strings.TrimSuffix(newPath, ".out"),
+					Content: string(content),
+				})
+			} else {
+				inputs = append(inputs, testtools.FileSpec{
+					Path:    newPath,
+					Content: string(content),
+				})
+				goldens = append(goldens, testtools.FileSpec{
+					Path:    newPath,
+					Content: string(content),
+				})
+			}
+
+			return nil
+		}); err != nil {
+			t.Errorf("filepath.Walk(%q) error: %v", filepath.Join(base, dir), err)
+		}
+
+		dir, cleanup := testtools.CreateFiles(t, inputs)
+		defer cleanup()
+
+		cmd := exec.Command(gazellePath, "-build_file_name=BUILD")
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		cmd.Dir = dir
+		if err := cmd.Run(); err != nil {
+			t.Fatal(err)
+		}
+
+		testtools.CheckFiles(t, dir, goldens)
+		if t.Failed() {
+			filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
+				if err != nil {
+					return err
+				}
+				t.Logf("%q exists", path)
+				return nil
+			})
+		}
+	}
+}
+
+func findGazelle() string {
+	gazellePath, ok := bazel.FindBinary("gazelle", "gazelle-skylib")
+	if !ok {
+		panic("could not find gazelle binary")
+	}
+	return gazellePath
+}
diff --git a/gazelle/testdata/README.md b/gazelle/testdata/README.md
new file mode 100644
index 00000000..66790434
--- /dev/null
+++ b/gazelle/testdata/README.md
@@ -0,0 +1,52 @@
+# Gazelle test cases
+
+This directory contains a suite of test cases for the Skylark language plugin
+for Gazelle.
+
+Please note that there are no `BUILD` or `BUILD.bazel` files in subdirs, insted
+there are `BUILD.in` and `BUILD.out` describing what the `BUILD` should look
+like initially and what the `BUILD` file should look like after the run. These
+names are special because they are not recognized by Bazel as a proper `BUILD`
+file, and therefore are included in the data dependency by the recursive data
+glob in `//gazelle:go_default_test`. If you would like to include any extremely
+complicated tests that contain proper `BUILD` files you will need to manually
+add them to the `//gazelle:go_default_test` target's `data` section.
+
+## `simple`
+
+Simple is a base test case that was used to validate the parser.
+
+## `nobuildfiles`
+
+A test just like `simple` that has no `BUILD` files at the beginning.
+
+## `import`
+
+Import is a test case that imports a `.bzl` from the same directory.
+
+## `multidir`
+
+Multidir is a test that has a `.bzl` that imports from a different dirrectory.
+
+## `tests`
+
+Using the skylib as an example, this test has `.bzl` files that end in
+`_tests.bzl` which are `load`ed into `BUILD` files and never imported by
+another repo.
+
+## `private`
+
+Using the skylib as an example, this test has `.bzl` files that live in a
+directory called `private` which is used to indicate that they are repo private.
+Note that this is distict from the expectations of go's `internal` where the
+relative position in the hierarchy determines the visibility.
+
+## `defaultvisibility`
+
+If the package declares a `default_visibility` the generated `bzl_library`
+should not set its own `visibility`.
+
+## `external`
+
+This test demonstrates that if you load from another repo, it is able to
+generate a `deps` entry for the dependency.
diff --git a/gazelle/testdata/defaultvisibility/BUILD.in b/gazelle/testdata/defaultvisibility/BUILD.in
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/defaultvisibility/BUILD.out b/gazelle/testdata/defaultvisibility/BUILD.out
new file mode 100644
index 00000000..7e210739
--- /dev/null
+++ b/gazelle/testdata/defaultvisibility/BUILD.out
@@ -0,0 +1,6 @@
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["//nested/dir:bar"],
+)
diff --git a/gazelle/testdata/defaultvisibility/WORKSPACE b/gazelle/testdata/defaultvisibility/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/defaultvisibility/foo.bzl b/gazelle/testdata/defaultvisibility/foo.bzl
new file mode 100644
index 00000000..ef1b937b
--- /dev/null
+++ b/gazelle/testdata/defaultvisibility/foo.bzl
@@ -0,0 +1 @@
+load("//nested/dir:bar.bzl", "asdf")
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.in b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.in
new file mode 100644
index 00000000..830932af
--- /dev/null
+++ b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.in
@@ -0,0 +1 @@
+package(default_visibility = ["//:__pkg__"])
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
new file mode 100644
index 00000000..771dfb62
--- /dev/null
+++ b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
@@ -0,0 +1,7 @@
+package(default_visibility = ["//:__pkg__"])
+
+bzl_library(
+    name = "bar",
+    srcs = ["bar.bzl"],
+)
+
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl b/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
new file mode 100644
index 00000000..3268d8d0
--- /dev/null
+++ b/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
@@ -0,0 +1,2 @@
+def asdf():
+    pass
diff --git a/gazelle/testdata/external/BUILD.in b/gazelle/testdata/external/BUILD.in
new file mode 100644
index 00000000..e267b5a1
--- /dev/null
+++ b/gazelle/testdata/external/BUILD.in
@@ -0,0 +1,6 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
diff --git a/gazelle/testdata/external/BUILD.out b/gazelle/testdata/external/BUILD.out
new file mode 100644
index 00000000..f586c430
--- /dev/null
+++ b/gazelle/testdata/external/BUILD.out
@@ -0,0 +1,13 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
+
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["@external_repo//path/to:file"],
+)
diff --git a/gazelle/testdata/external/WORKSPACE b/gazelle/testdata/external/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/external/foo.bzl b/gazelle/testdata/external/foo.bzl
new file mode 100644
index 00000000..43bec45b
--- /dev/null
+++ b/gazelle/testdata/external/foo.bzl
@@ -0,0 +1 @@
+load("@external_repo//path/to:file.bzl", "func")
diff --git a/gazelle/testdata/import/BUILD.in b/gazelle/testdata/import/BUILD.in
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/import/BUILD.out b/gazelle/testdata/import/BUILD.out
new file mode 100644
index 00000000..dd5822d9
--- /dev/null
+++ b/gazelle/testdata/import/BUILD.out
@@ -0,0 +1,12 @@
+bzl_library(
+    name = "bar",
+    srcs = ["bar.bzl"],
+    visibility = ["//visibility:public"],
+)
+
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["//:bar"],
+)
diff --git a/gazelle/testdata/import/WORKSPACE b/gazelle/testdata/import/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/import/bar.bzl b/gazelle/testdata/import/bar.bzl
new file mode 100644
index 00000000..3268d8d0
--- /dev/null
+++ b/gazelle/testdata/import/bar.bzl
@@ -0,0 +1,2 @@
+def asdf():
+    pass
diff --git a/gazelle/testdata/import/foo.bzl b/gazelle/testdata/import/foo.bzl
new file mode 100644
index 00000000..e7c55148
--- /dev/null
+++ b/gazelle/testdata/import/foo.bzl
@@ -0,0 +1 @@
+load("//:bar.bzl", "asdf")
diff --git a/gazelle/testdata/multidir/BUILD.in b/gazelle/testdata/multidir/BUILD.in
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/multidir/BUILD.out b/gazelle/testdata/multidir/BUILD.out
new file mode 100644
index 00000000..7e210739
--- /dev/null
+++ b/gazelle/testdata/multidir/BUILD.out
@@ -0,0 +1,6 @@
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["//nested/dir:bar"],
+)
diff --git a/gazelle/testdata/multidir/WORKSPACE b/gazelle/testdata/multidir/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/multidir/foo.bzl b/gazelle/testdata/multidir/foo.bzl
new file mode 100644
index 00000000..ef1b937b
--- /dev/null
+++ b/gazelle/testdata/multidir/foo.bzl
@@ -0,0 +1 @@
+load("//nested/dir:bar.bzl", "asdf")
diff --git a/gazelle/testdata/multidir/nested/dir/BUILD.out b/gazelle/testdata/multidir/nested/dir/BUILD.out
new file mode 100644
index 00000000..6477e60c
--- /dev/null
+++ b/gazelle/testdata/multidir/nested/dir/BUILD.out
@@ -0,0 +1,6 @@
+bzl_library(
+    name = "bar",
+    srcs = ["bar.bzl"],
+    visibility = ["//visibility:public"],
+)
+
diff --git a/gazelle/testdata/multidir/nested/dir/bar.bzl b/gazelle/testdata/multidir/nested/dir/bar.bzl
new file mode 100644
index 00000000..3268d8d0
--- /dev/null
+++ b/gazelle/testdata/multidir/nested/dir/bar.bzl
@@ -0,0 +1,2 @@
+def asdf():
+    pass
diff --git a/gazelle/testdata/nobuildfiles/BUILD.out b/gazelle/testdata/nobuildfiles/BUILD.out
new file mode 100644
index 00000000..2d2a8f9e
--- /dev/null
+++ b/gazelle/testdata/nobuildfiles/BUILD.out
@@ -0,0 +1,5 @@
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+)
diff --git a/gazelle/testdata/nobuildfiles/WORKSPACE b/gazelle/testdata/nobuildfiles/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/nobuildfiles/foo.bzl b/gazelle/testdata/nobuildfiles/foo.bzl
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/private/BUILD.in b/gazelle/testdata/private/BUILD.in
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/private/BUILD.out b/gazelle/testdata/private/BUILD.out
new file mode 100644
index 00000000..05d739f4
--- /dev/null
+++ b/gazelle/testdata/private/BUILD.out
@@ -0,0 +1,6 @@
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+    deps = ["//nested/private:bar"],
+)
diff --git a/gazelle/testdata/private/WORKSPACE b/gazelle/testdata/private/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/private/foo.bzl b/gazelle/testdata/private/foo.bzl
new file mode 100644
index 00000000..599e8e2b
--- /dev/null
+++ b/gazelle/testdata/private/foo.bzl
@@ -0,0 +1 @@
+load("//nested/private:bar.bzl", "asdf")
diff --git a/gazelle/testdata/private/nested/private/BUILD.out b/gazelle/testdata/private/nested/private/BUILD.out
new file mode 100644
index 00000000..04dba8d5
--- /dev/null
+++ b/gazelle/testdata/private/nested/private/BUILD.out
@@ -0,0 +1,5 @@
+bzl_library(
+    name = "bar",
+    srcs = ["bar.bzl"],
+)
+
diff --git a/gazelle/testdata/private/nested/private/bar.bzl b/gazelle/testdata/private/nested/private/bar.bzl
new file mode 100644
index 00000000..3268d8d0
--- /dev/null
+++ b/gazelle/testdata/private/nested/private/bar.bzl
@@ -0,0 +1,2 @@
+def asdf():
+    pass
diff --git a/gazelle/testdata/simple/BUILD.in b/gazelle/testdata/simple/BUILD.in
new file mode 100644
index 00000000..e267b5a1
--- /dev/null
+++ b/gazelle/testdata/simple/BUILD.in
@@ -0,0 +1,6 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
diff --git a/gazelle/testdata/simple/BUILD.out b/gazelle/testdata/simple/BUILD.out
new file mode 100644
index 00000000..3e57f6ab
--- /dev/null
+++ b/gazelle/testdata/simple/BUILD.out
@@ -0,0 +1,12 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
+
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+)
diff --git a/gazelle/testdata/simple/WORKSPACE b/gazelle/testdata/simple/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/simple/foo.bzl b/gazelle/testdata/simple/foo.bzl
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/tests/BUILD.in b/gazelle/testdata/tests/BUILD.in
new file mode 100644
index 00000000..e267b5a1
--- /dev/null
+++ b/gazelle/testdata/tests/BUILD.in
@@ -0,0 +1,6 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
diff --git a/gazelle/testdata/tests/BUILD.out b/gazelle/testdata/tests/BUILD.out
new file mode 100644
index 00000000..3e57f6ab
--- /dev/null
+++ b/gazelle/testdata/tests/BUILD.out
@@ -0,0 +1,12 @@
+# Some comment to be preserved
+
+filegroup(
+    name = "allfiles",
+    srcs = glob(["**"]),
+)
+
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+)
diff --git a/gazelle/testdata/tests/WORKSPACE b/gazelle/testdata/tests/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/tests/foo.bzl b/gazelle/testdata/tests/foo.bzl
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/tests/foo_tests.bzl b/gazelle/testdata/tests/foo_tests.bzl
new file mode 100644
index 00000000..e69de29b
diff --git a/lib/BUILD b/lib/BUILD
index c959bcc1..d17caa57 100644
--- a/lib/BUILD
+++ b/lib/BUILD
@@ -93,3 +93,8 @@ filegroup(
         "//distribution:__pkg__",
     ],
 )
+
+bzl_library(
+    name = "old_sets",
+    srcs = ["old_sets.bzl"],
+)
diff --git a/rules/BUILD b/rules/BUILD
index 9c6c047c..bad361b8 100644
--- a/rules/BUILD
+++ b/rules/BUILD
@@ -81,3 +81,8 @@ exports_files(
     glob(["*.bzl"]),
     visibility = ["//:__subpackages__"],
 )
+
+bzl_library(
+    name = "select_file",
+    srcs = ["select_file.bzl"],
+)

From 1a355d66697d0fb904e2494f4390b580980a74f1 Mon Sep 17 00:00:00 2001
From: Andrew Z Allen <me@andrewzallen.com>
Date: Fri, 29 May 2020 17:42:42 -0600
Subject: [PATCH 2/9] Respond to reviewer comments

---
 BUILD                                         |  3 +-
 WORKSPACE                                     |  6 ----
 gazelle/BUILD                                 |  4 +--
 gazelle/gazelle.go                            | 29 ++++++++-----------
 gazelle/testdata/defaultvisibility/foo.bzl    |  8 ++++-
 .../defaultvisibility/nested/dir/BUILD.out    |  1 -
 .../defaultvisibility/nested/dir/bar.bzl      |  4 +++
 gazelle/testdata/external/foo.bzl             |  6 ++++
 gazelle/testdata/import/bar.bzl               |  6 +++-
 gazelle/testdata/import/foo.bzl               |  8 ++++-
 gazelle/testdata/multidir/foo.bzl             |  8 ++++-
 .../testdata/multidir/nested/dir/BUILD.out    |  1 -
 gazelle/testdata/multidir/nested/dir/bar.bzl  |  6 +++-
 gazelle/testdata/private/foo.bzl              |  8 ++++-
 .../testdata/private/nested/private/BUILD.out |  1 -
 .../testdata/private/nested/private/bar.bzl   |  6 +++-
 16 files changed, 68 insertions(+), 37 deletions(-)

diff --git a/BUILD b/BUILD
index ec378c67..1201291f 100644
--- a/BUILD
+++ b/BUILD
@@ -1,4 +1,5 @@
 load("//:bzl_library.bzl", "bzl_library")
+load("@bazel_gazelle//:def.bzl", "gazelle")
 
 licenses(["notice"])
 
@@ -88,8 +89,6 @@ filegroup(
 # included by dependencies on bazel-skylib nor packaged in the distribution
 # release.
 
-load("@bazel_gazelle//:def.bzl", "gazelle")
-
 gazelle(
     name = "gazelle",
     gazelle = "//gazelle:gazelle-skylib",
diff --git a/WORKSPACE b/WORKSPACE
index cefdfa0a..803e3696 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -69,9 +69,3 @@ http_archive(
 load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
 
 gazelle_dependencies()
-
-go_repository(
-    name = "net_starlark_go",
-    commit = "0aa95694c76801c1528349fb86033b9098d634fc",
-    importpath = "go.starlark.net",
-)
diff --git a/gazelle/BUILD b/gazelle/BUILD
index ca23dcf3..bb6d605c 100644
--- a/gazelle/BUILD
+++ b/gazelle/BUILD
@@ -1,5 +1,5 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
-load("@bazel_gazelle//:def.bzl", "DEFAULT_LANGUAGES", "gazelle_binary")
+load("@bazel_gazelle//:def.bzl", "gazelle_binary")
 
 # gazelle:exclude testdata
 
@@ -15,7 +15,7 @@ go_library(
         "@bazel_gazelle//repo:go_default_library",
         "@bazel_gazelle//resolve:go_default_library",
         "@bazel_gazelle//rule:go_default_library",
-        "@net_starlark_go//syntax:go_default_library",
+        "@com_github_bazelbuild_buildtools//build:go_default_library",
     ],
 )
 
diff --git a/gazelle/gazelle.go b/gazelle/gazelle.go
index 9b302008..c114c9ac 100644
--- a/gazelle/gazelle.go
+++ b/gazelle/gazelle.go
@@ -27,6 +27,7 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"log"
 	"path/filepath"
 	"sort"
 	"strings"
@@ -38,7 +39,7 @@ import (
 	"github.com/bazelbuild/bazel-gazelle/resolve"
 	"github.com/bazelbuild/bazel-gazelle/rule"
 
-	"go.starlark.net/syntax"
+	"github.com/bazelbuild/buildtools/build"
 )
 
 const languageName = "starlark"
@@ -154,10 +155,9 @@ func (*bzlLibraryLang) Resolve(c *config.Config, ix *resolve.RuleIndex, rc *repo
 				Imp:  imp,
 			}
 			matches := ix.FindRulesByImport(res, languageName)
-			fmt.Printf("ix: %v\n", ix)
 
 			if len(matches) == 0 {
-				fmt.Printf("Didn't find match for %q\n", imp)
+				log.Printf("%s: %q was not found in dependency index. Skipping. This may result in an incomplete deps section and require manual BUILD file intervention.\n", from.String(), imp)
 			}
 
 			for _, m := range matches {
@@ -220,10 +220,10 @@ func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.Genera
 			fullPath := filepath.Join(args.Dir, f)
 			loads, err := getBzlFileLoads(fullPath)
 			if err != nil {
-				fmt.Printf("Error getting getBzlFileLoads(%q, %q): %v", args.Dir, f, err)
-				// Don't `continue` since it is reasonable to create a target even without deps.
+				log.Printf("%s: contains symtax errors: %v", fullPath, err)
+				// Don't `continue` since it is reasonable to create a target even
+				// without deps.
 			}
-			fmt.Printf("loads: %v\n", loads)
 
 			rules = append(rules, r)
 			imports = append(imports, loads)
@@ -240,22 +240,17 @@ func getBzlFileLoads(path string) ([]string, error) {
 	if err != nil {
 		return nil, fmt.Errorf("ioutil.ReadFile(%q) error: %v", path, err)
 	}
-	ast, err := syntax.Parse(path, f, 0644)
+	ast, err := build.ParseBuild(path, f)
 	if err != nil {
-		return nil, fmt.Errorf("syntax.Parse(%q) error: %v", f, err)
+		return nil, fmt.Errorf("build.Parse(%q) error: %v", f, err)
 	}
 
 	var loads []string
-	syntax.Walk(ast, func(n syntax.Node) bool {
-		if l, ok := n.(*syntax.LoadStmt); ok {
-			val, ok := l.Module.Value.(string)
-			if !ok {
-				fmt.Printf("The load statement at %s:%s is not a simple string. Therefore, bazel targets can not be generated automatically for it.", path, l.Module.TokenPos)
-				return true
-			}
-			loads = append(loads, val)
+	build.WalkOnce(ast, func(expr *build.Expr) {
+		n := *expr
+		if l, ok := n.(*build.LoadStmt); ok {
+			loads = append(loads, l.Module.Value)
 		}
-		return true
 	})
 	sort.Strings(loads)
 
diff --git a/gazelle/testdata/defaultvisibility/foo.bzl b/gazelle/testdata/defaultvisibility/foo.bzl
index ef1b937b..1191303a 100644
--- a/gazelle/testdata/defaultvisibility/foo.bzl
+++ b/gazelle/testdata/defaultvisibility/foo.bzl
@@ -1 +1,7 @@
-load("//nested/dir:bar.bzl", "asdf")
+"""
+Doc string
+"""
+
+load("//nested/dir:bar.bzl", "func")
+
+func()
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
index 771dfb62..15633a9f 100644
--- a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
+++ b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
@@ -4,4 +4,3 @@ bzl_library(
     name = "bar",
     srcs = ["bar.bzl"],
 )
-
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl b/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
index 3268d8d0..8ab1fcb5 100644
--- a/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
+++ b/gazelle/testdata/defaultvisibility/nested/dir/bar.bzl
@@ -1,2 +1,6 @@
+"""
+Doc string
+"""
+
 def asdf():
     pass
diff --git a/gazelle/testdata/external/foo.bzl b/gazelle/testdata/external/foo.bzl
index 43bec45b..ad548a58 100644
--- a/gazelle/testdata/external/foo.bzl
+++ b/gazelle/testdata/external/foo.bzl
@@ -1 +1,7 @@
+"""
+Test sample code.
+"""
+
 load("@external_repo//path/to:file.bzl", "func")
+
+func()
diff --git a/gazelle/testdata/import/bar.bzl b/gazelle/testdata/import/bar.bzl
index 3268d8d0..7ffea515 100644
--- a/gazelle/testdata/import/bar.bzl
+++ b/gazelle/testdata/import/bar.bzl
@@ -1,2 +1,6 @@
-def asdf():
+"""
+Doc string
+"""
+
+def func():
     pass
diff --git a/gazelle/testdata/import/foo.bzl b/gazelle/testdata/import/foo.bzl
index e7c55148..eb8d33c6 100644
--- a/gazelle/testdata/import/foo.bzl
+++ b/gazelle/testdata/import/foo.bzl
@@ -1 +1,7 @@
-load("//:bar.bzl", "asdf")
+"""
+Doc string
+"""
+
+load("//:bar.bzl", "func")
+
+func()
diff --git a/gazelle/testdata/multidir/foo.bzl b/gazelle/testdata/multidir/foo.bzl
index ef1b937b..1191303a 100644
--- a/gazelle/testdata/multidir/foo.bzl
+++ b/gazelle/testdata/multidir/foo.bzl
@@ -1 +1,7 @@
-load("//nested/dir:bar.bzl", "asdf")
+"""
+Doc string
+"""
+
+load("//nested/dir:bar.bzl", "func")
+
+func()
diff --git a/gazelle/testdata/multidir/nested/dir/BUILD.out b/gazelle/testdata/multidir/nested/dir/BUILD.out
index 6477e60c..a575eba2 100644
--- a/gazelle/testdata/multidir/nested/dir/BUILD.out
+++ b/gazelle/testdata/multidir/nested/dir/BUILD.out
@@ -3,4 +3,3 @@ bzl_library(
     srcs = ["bar.bzl"],
     visibility = ["//visibility:public"],
 )
-
diff --git a/gazelle/testdata/multidir/nested/dir/bar.bzl b/gazelle/testdata/multidir/nested/dir/bar.bzl
index 3268d8d0..7ffea515 100644
--- a/gazelle/testdata/multidir/nested/dir/bar.bzl
+++ b/gazelle/testdata/multidir/nested/dir/bar.bzl
@@ -1,2 +1,6 @@
-def asdf():
+"""
+Doc string
+"""
+
+def func():
     pass
diff --git a/gazelle/testdata/private/foo.bzl b/gazelle/testdata/private/foo.bzl
index 599e8e2b..bf33a05c 100644
--- a/gazelle/testdata/private/foo.bzl
+++ b/gazelle/testdata/private/foo.bzl
@@ -1 +1,7 @@
-load("//nested/private:bar.bzl", "asdf")
+"""
+Test sample code.
+"""
+
+load("//nested/private:bar.bzl", "func")
+
+func()
diff --git a/gazelle/testdata/private/nested/private/BUILD.out b/gazelle/testdata/private/nested/private/BUILD.out
index 04dba8d5..2c7085ab 100644
--- a/gazelle/testdata/private/nested/private/BUILD.out
+++ b/gazelle/testdata/private/nested/private/BUILD.out
@@ -2,4 +2,3 @@ bzl_library(
     name = "bar",
     srcs = ["bar.bzl"],
 )
-
diff --git a/gazelle/testdata/private/nested/private/bar.bzl b/gazelle/testdata/private/nested/private/bar.bzl
index 3268d8d0..c8a48713 100644
--- a/gazelle/testdata/private/nested/private/bar.bzl
+++ b/gazelle/testdata/private/nested/private/bar.bzl
@@ -1,2 +1,6 @@
-def asdf():
+"""
+Test sample code.
+"""
+
+def func():
     pass

From 3cab68cc604a83673356346c20c82169413f0c73 Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 19:37:16 +0000
Subject: [PATCH 3/9] More reviewer comments

---
 BUILD                                         | 10 ---
 CODEOWNERS                                    |  1 +
 WORKSPACE                                     |  2 +-
 gazelle/BUILD                                 | 12 +--
 gazelle/gazelle.go                            | 80 +++++++++++++++----
 gazelle/testdata/README.md                    |  4 +
 gazelle/testdata/defaultvisibility/BUILD.out  |  2 +
 .../defaultvisibility/nested/dir/BUILD.out    |  2 +
 gazelle/testdata/empty/BUILD.in               |  7 ++
 gazelle/testdata/empty/BUILD.out              |  7 ++
 gazelle/testdata/empty/WORKSPACE              |  0
 gazelle/testdata/empty/foo.bzl                |  0
 gazelle/testdata/external/BUILD.in            |  2 +
 gazelle/testdata/external/BUILD.out           |  2 +
 gazelle/testdata/import/BUILD.out             |  2 +
 gazelle/testdata/multidir/BUILD.out           |  2 +
 .../testdata/multidir/nested/dir/BUILD.out    |  2 +
 gazelle/testdata/nobuildfiles/BUILD.out       |  2 +
 gazelle/testdata/private/BUILD.out            |  2 +
 .../testdata/private/nested/private/BUILD.out |  2 +
 gazelle/testdata/simple/BUILD.out             |  2 +
 gazelle/testdata/tests/BUILD.out              |  2 +
 22 files changed, 116 insertions(+), 31 deletions(-)
 create mode 100644 gazelle/testdata/empty/BUILD.in
 create mode 100644 gazelle/testdata/empty/BUILD.out
 create mode 100644 gazelle/testdata/empty/WORKSPACE
 create mode 100644 gazelle/testdata/empty/foo.bzl

diff --git a/BUILD b/BUILD
index 1201291f..ad1dbfb8 100644
--- a/BUILD
+++ b/BUILD
@@ -1,5 +1,4 @@
 load("//:bzl_library.bzl", "bzl_library")
-load("@bazel_gazelle//:def.bzl", "gazelle")
 
 licenses(["notice"])
 
@@ -84,12 +83,3 @@ filegroup(
         "//rules:bins",
     ],
 )
-
-# Below this line is for development purposes only and should thus not be
-# included by dependencies on bazel-skylib nor packaged in the distribution
-# release.
-
-gazelle(
-    name = "gazelle",
-    gazelle = "//gazelle:gazelle-skylib",
-)
diff --git a/CODEOWNERS b/CODEOWNERS
index 2b22b23a..07b74fad 100644
--- a/CODEOWNERS
+++ b/CODEOWNERS
@@ -1,3 +1,4 @@
 * @c-parsons @laurentlb @jin @aiuto
 distribution/ @aiuto @fwe
 rules/ @juliexxia
+gazelle/ @achew22 @jayconrod
diff --git a/WORKSPACE b/WORKSPACE
index 803e3696..c5a2130d 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -66,6 +66,6 @@ http_archive(
 # Another Gazelle repository hint.
 # gazelle:repository go_repository name=bazel_gazelle importpath=github.com/bazelbuild/bazel-gazelle/testtools
 
-load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
+load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")
 
 gazelle_dependencies()
diff --git a/gazelle/BUILD b/gazelle/BUILD
index bb6d605c..d20212cb 100644
--- a/gazelle/BUILD
+++ b/gazelle/BUILD
@@ -1,5 +1,5 @@
 load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
-load("@bazel_gazelle//:def.bzl", "gazelle_binary")
+load("@bazel_gazelle//:def.bzl", "gazelle", "gazelle_binary")
 
 # gazelle:exclude testdata
 
@@ -12,6 +12,7 @@ go_library(
         "@bazel_gazelle//config:go_default_library",
         "@bazel_gazelle//label:go_default_library",
         "@bazel_gazelle//language:go_default_library",
+        "@bazel_gazelle//pathtools:go_default_library",
         "@bazel_gazelle//repo:go_default_library",
         "@bazel_gazelle//resolve:go_default_library",
         "@bazel_gazelle//rule:go_default_library",
@@ -39,13 +40,14 @@ go_test(
 gazelle_binary(
     name = "gazelle-skylib",
     languages = [":go_default_library"],
-    msan = "off",
-    pure = "off",
-    race = "off",
-    static = "off",
     visibility = [
         # Also make the binary available in the root of the repo for use, but
         # not externally.
         "//:__pkg__",
     ],
 )
+
+gazelle(
+    name = "gazelle",
+    gazelle = "//gazelle:gazelle-skylib",
+)
diff --git a/gazelle/gazelle.go b/gazelle/gazelle.go
index c114c9ac..ec3edc6e 100644
--- a/gazelle/gazelle.go
+++ b/gazelle/gazelle.go
@@ -35,6 +35,7 @@ import (
 	"github.com/bazelbuild/bazel-gazelle/config"
 	"github.com/bazelbuild/bazel-gazelle/label"
 	"github.com/bazelbuild/bazel-gazelle/language"
+	"github.com/bazelbuild/bazel-gazelle/pathtools"
 	"github.com/bazelbuild/bazel-gazelle/repo"
 	"github.com/bazelbuild/bazel-gazelle/resolve"
 	"github.com/bazelbuild/bazel-gazelle/rule"
@@ -91,7 +92,12 @@ func (*bzlLibraryLang) Kinds() map[string]rule.KindInfo {
 // Loads returns .bzl files and symbols they define. Every rule generated by
 // GenerateRules, now or in the past, should be loadable from one of these
 // files.
-func (*bzlLibraryLang) Loads() []rule.LoadInfo { return nil }
+func (*bzlLibraryLang) Loads() []rule.LoadInfo {
+	return []rule.LoadInfo{{
+		Name:    "@bazel_skylib//:bzl_library.bzl",
+		Symbols: []string{"bzl_library"},
+	}}
+}
 
 // Fix repairs deprecated usage of language-specific rules in f. This is
 // called before the file is indexed. Unless c.ShouldFix is true, fixes
@@ -146,8 +152,9 @@ func (*bzlLibraryLang) Resolve(c *config.Config, ix *resolve.RuleIndex, rc *repo
 
 	deps := make([]string, 0, len(imports))
 	for _, imp := range imports {
-		if strings.HasPrefix(imp, "@") {
-			// This is a dependency that is external to the current repo.
+		if strings.HasPrefix(imp, "@") || !c.IndexLibraries {
+			// This is a dependency that is external to the current repo, or indexing
+			// is disabled so take a guess at what hte target name should be.
 			deps = append(deps, strings.TrimSuffix(imp, fileType))
 		} else {
 			res := resolve.ImportSpec{
@@ -195,23 +202,15 @@ var kinds = map[string]rule.KindInfo{
 func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.GenerateResult {
 	var rules []*rule.Rule
 	var imports []interface{}
-	for _, f := range append(args.RegularFiles) {
-		if ignoreSuffix.Matches(f) {
-			continue
-		}
-		if strings.HasSuffix(f, fileType) {
+	for _, f := range append(args.RegularFiles, args.GenFiles...) {
+		if isBzlSourceFile(f) {
 			name := strings.TrimSuffix(f, fileType)
 			r := rule.NewRule("bzl_library", name)
 
 			r.SetAttr("srcs", []string{f})
 
 			if args.File == nil || !args.File.HasDefaultVisibility() {
-				var inPrivateDir bool
-				for _, d := range strings.Split(args.Dir, string(filepath.Separator)) {
-					if d == "private" {
-						inPrivateDir = true
-					}
-				}
+				inPrivateDir := pathtools.Index(args.Rel, "private") >= 0
 				if !inPrivateDir {
 					r.SetAttr("visibility", []string{"//visibility:public"})
 				}
@@ -220,7 +219,7 @@ func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.Genera
 			fullPath := filepath.Join(args.Dir, f)
 			loads, err := getBzlFileLoads(fullPath)
 			if err != nil {
-				log.Printf("%s: contains symtax errors: %v", fullPath, err)
+				log.Printf("%s: contains syntax errors: %v", fullPath, err)
 				// Don't `continue` since it is reasonable to create a target even
 				// without deps.
 			}
@@ -229,9 +228,11 @@ func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.Genera
 			imports = append(imports, loads)
 		}
 	}
+
 	return language.GenerateResult{
 		Gen:     rules,
 		Imports: imports,
+		Empty:   generateEmpty(args),
 	}
 }
 
@@ -256,3 +257,52 @@ func getBzlFileLoads(path string) ([]string, error) {
 
 	return loads, nil
 }
+
+func isBzlSourceFile(f string) bool {
+	return strings.HasSuffix(f, fileType) && !ignoreSuffix.Matches(f)
+}
+
+// generateEmpty generates the list of rules that don't need to exist in the
+// BUILD file any more.
+// For each bzl_library rule in args.File that only has srcs that aren't in
+// args.RegularFiles or args.GenFiles, add a bzl_library with no srcs or deps.
+// That will let Gazelle delete bzl_library rules after the corresponding .bzl
+// files are deleted.
+func generateEmpty(args language.GenerateArgs) []*rule.Rule {
+	var ret []*rule.Rule
+	if args.File == nil {
+		return ret
+	}
+	for _, r := range args.File.Rules {
+		if r.Kind() != "bzl_library" {
+			continue
+		}
+		name := r.AttrString("name")
+		srcs := srcsList(r.AttrStrings("srcs"))
+
+		for _, f := range args.RegularFiles {
+			if srcs.Contains(f) {
+				continue
+			}
+		}
+		for _, f := range args.GenFiles {
+			if srcs.Contains(f) {
+				continue
+			}
+		}
+
+		ret = append(ret, rule.NewRule("bzl_library", name))
+	}
+	return ret
+}
+
+type srcsList []string
+
+func (s srcsList) Contains(m string) bool {
+	for _, e := range s {
+		if e == m {
+			return true
+		}
+	}
+	return false
+}
diff --git a/gazelle/testdata/README.md b/gazelle/testdata/README.md
index 66790434..a6a36031 100644
--- a/gazelle/testdata/README.md
+++ b/gazelle/testdata/README.md
@@ -50,3 +50,7 @@ should not set its own `visibility`.
 
 This test demonstrates that if you load from another repo, it is able to
 generate a `deps` entry for the dependency.
+
+## `empty`
+
+Gazelle has the ability to remove old and unused targets. Test that.
diff --git a/gazelle/testdata/defaultvisibility/BUILD.out b/gazelle/testdata/defaultvisibility/BUILD.out
index 7e210739..44c1495e 100644
--- a/gazelle/testdata/defaultvisibility/BUILD.out
+++ b/gazelle/testdata/defaultvisibility/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "foo",
     srcs = ["foo.bzl"],
diff --git a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
index 15633a9f..8394b9c8 100644
--- a/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
+++ b/gazelle/testdata/defaultvisibility/nested/dir/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 package(default_visibility = ["//:__pkg__"])
 
 bzl_library(
diff --git a/gazelle/testdata/empty/BUILD.in b/gazelle/testdata/empty/BUILD.in
new file mode 100644
index 00000000..80690c9e
--- /dev/null
+++ b/gazelle/testdata/empty/BUILD.in
@@ -0,0 +1,7 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
+bzl_library(
+    name = "weirdly_named_target_that_will_be_renamed",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+)
diff --git a/gazelle/testdata/empty/BUILD.out b/gazelle/testdata/empty/BUILD.out
new file mode 100644
index 00000000..ac0e990f
--- /dev/null
+++ b/gazelle/testdata/empty/BUILD.out
@@ -0,0 +1,7 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
+bzl_library(
+    name = "foo",
+    srcs = ["foo.bzl"],
+    visibility = ["//visibility:public"],
+)
diff --git a/gazelle/testdata/empty/WORKSPACE b/gazelle/testdata/empty/WORKSPACE
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/empty/foo.bzl b/gazelle/testdata/empty/foo.bzl
new file mode 100644
index 00000000..e69de29b
diff --git a/gazelle/testdata/external/BUILD.in b/gazelle/testdata/external/BUILD.in
index e267b5a1..e7bc836e 100644
--- a/gazelle/testdata/external/BUILD.in
+++ b/gazelle/testdata/external/BUILD.in
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Some comment to be preserved
 
 filegroup(
diff --git a/gazelle/testdata/external/BUILD.out b/gazelle/testdata/external/BUILD.out
index f586c430..c70685fe 100644
--- a/gazelle/testdata/external/BUILD.out
+++ b/gazelle/testdata/external/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Some comment to be preserved
 
 filegroup(
diff --git a/gazelle/testdata/import/BUILD.out b/gazelle/testdata/import/BUILD.out
index dd5822d9..a19a11aa 100644
--- a/gazelle/testdata/import/BUILD.out
+++ b/gazelle/testdata/import/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "bar",
     srcs = ["bar.bzl"],
diff --git a/gazelle/testdata/multidir/BUILD.out b/gazelle/testdata/multidir/BUILD.out
index 7e210739..44c1495e 100644
--- a/gazelle/testdata/multidir/BUILD.out
+++ b/gazelle/testdata/multidir/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "foo",
     srcs = ["foo.bzl"],
diff --git a/gazelle/testdata/multidir/nested/dir/BUILD.out b/gazelle/testdata/multidir/nested/dir/BUILD.out
index a575eba2..07ec8ce6 100644
--- a/gazelle/testdata/multidir/nested/dir/BUILD.out
+++ b/gazelle/testdata/multidir/nested/dir/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "bar",
     srcs = ["bar.bzl"],
diff --git a/gazelle/testdata/nobuildfiles/BUILD.out b/gazelle/testdata/nobuildfiles/BUILD.out
index 2d2a8f9e..ac0e990f 100644
--- a/gazelle/testdata/nobuildfiles/BUILD.out
+++ b/gazelle/testdata/nobuildfiles/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "foo",
     srcs = ["foo.bzl"],
diff --git a/gazelle/testdata/private/BUILD.out b/gazelle/testdata/private/BUILD.out
index 05d739f4..5709f874 100644
--- a/gazelle/testdata/private/BUILD.out
+++ b/gazelle/testdata/private/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "foo",
     srcs = ["foo.bzl"],
diff --git a/gazelle/testdata/private/nested/private/BUILD.out b/gazelle/testdata/private/nested/private/BUILD.out
index 2c7085ab..eb2e935d 100644
--- a/gazelle/testdata/private/nested/private/BUILD.out
+++ b/gazelle/testdata/private/nested/private/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 bzl_library(
     name = "bar",
     srcs = ["bar.bzl"],
diff --git a/gazelle/testdata/simple/BUILD.out b/gazelle/testdata/simple/BUILD.out
index 3e57f6ab..3c71d561 100644
--- a/gazelle/testdata/simple/BUILD.out
+++ b/gazelle/testdata/simple/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Some comment to be preserved
 
 filegroup(
diff --git a/gazelle/testdata/tests/BUILD.out b/gazelle/testdata/tests/BUILD.out
index 3e57f6ab..3c71d561 100644
--- a/gazelle/testdata/tests/BUILD.out
+++ b/gazelle/testdata/tests/BUILD.out
@@ -1,3 +1,5 @@
+load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+
 # Some comment to be preserved
 
 filegroup(

From 79fe22a4fa0f5ffc8da387aa8a1f083d018e3f15 Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 19:42:21 +0000
Subject: [PATCH 4/9] Fixup for windows

---
 gazelle/gazelle_test.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
index b4ced390..e980ce2c 100644
--- a/gazelle/gazelle_test.go
+++ b/gazelle/gazelle_test.go
@@ -35,7 +35,11 @@ const base = "testdata"
 // directory in `testdata/*`. Please see `testdata/README.md` for more
 // information on each test.
 func TestGazelleBinary(t *testing.T) {
-	ds, err := ioutil.ReadDir(base)
+	testdata, err := bazel.Runfile(base)
+	if err != nil {
+		t.Errorf("bazel.Runfile(%q) error: %v", base, err)
+	}
+	ds, err := ioutil.ReadDir(testdata)
 	if err != nil {
 		t.Errorf("ioutil.ReadDir(%q) error: %v", base, err)
 	}

From a7de5f3f54b48ea2ff9dba6b8794162810bb628a Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 19:49:03 +0000
Subject: [PATCH 5/9] Fixup some lint errors

---
 WORKSPACE                                      | 18 +++++++-----------
 gazelle/gazelle_test.go                        | 12 ++++++------
 gazelle/testdata/private/BUILD.out             |  2 +-
 gazelle/testdata/private/foo.bzl               |  2 +-
 .../private/{nested => }/private/BUILD.out     |  0
 .../private/{nested => }/private/bar.bzl       |  0
 6 files changed, 15 insertions(+), 19 deletions(-)
 rename gazelle/testdata/private/{nested => }/private/BUILD.out (100%)
 rename gazelle/testdata/private/{nested => }/private/bar.bzl (100%)

diff --git a/WORKSPACE b/WORKSPACE
index c5a2130d..c79cb22b 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -10,14 +10,20 @@ maybe(
     url = "https://github.com/bazelbuild/bazel-federation/releases/download/0.0.1/bazel_federation-0.0.1.tar.gz",
 )
 
-load("@bazel_federation//:repositories.bzl", "bazel_skylib_deps")
+load("@bazel_federation//:repositories.bzl", "bazel_skylib_deps", "rules_go")
 
 bazel_skylib_deps()
 
+rules_go()
+
 load("@bazel_federation//setup:bazel_skylib.bzl", "bazel_skylib_setup")
 
 bazel_skylib_setup()
 
+load("@bazel_federation//setup:rules_go.bzl", "rules_go_setup")
+
+rules_go_setup()
+
 # Below this line is for documentation generation only,
 # and should thus not be included by dependencies on
 # bazel-skylib.
@@ -41,20 +47,10 @@ maybe(
     ],
 )
 
-# Below are dependencies for the generator.
-
-load("@bazel_federation//:repositories.bzl", "rules_go")
-
-rules_go()
 # Provide a repository hint for Gazelle to inform it that the go package
 # github.com/bazelbuild/rules_go is available from io_bazel_rules_go and it
 # doesn't need to duplicatively fetch it.
 # gazelle:repository go_repository name=io_bazel_rules_go importpath=github.com/bazelbuild/rules_go
-
-load("@bazel_federation//setup:rules_go.bzl", "rules_go_setup")
-
-rules_go_setup()
-
 http_archive(
     name = "bazel_gazelle",
     sha256 = "bfd86b3cbe855d6c16c6fce60d76bd51f5c8dbc9cfcaef7a2bb5c1aafd0710e8",
diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
index e980ce2c..f3f63145 100644
--- a/gazelle/gazelle_test.go
+++ b/gazelle/gazelle_test.go
@@ -29,7 +29,7 @@ import (
 
 var gazellePath = findGazelle()
 
-const base = "testdata"
+const base = "gazelle/testdata"
 
 // TestGazelleBinary runs a gazelle binary with starlib installed on each
 // directory in `testdata/*`. Please see `testdata/README.md` for more
@@ -45,17 +45,17 @@ func TestGazelleBinary(t *testing.T) {
 	}
 	for _, d := range ds {
 		if d.IsDir() {
-			t.Run(d.Name(), testPath(d.Name()))
+			t.Run(d.Name(), testPath(testdata, d.Name()))
 		}
 	}
 }
 
-func testPath(dir string) func(t *testing.T) {
+func testPath(testdata string, dir string) func(t *testing.T) {
 	return func(t *testing.T) {
 		var inputs []testtools.FileSpec
 		var goldens []testtools.FileSpec
 
-		if err := filepath.Walk(filepath.Join(base, dir), func(path string, info os.FileInfo, err error) error {
+		if err := filepath.Walk(filepath.Join(testdata, dir), func(path string, info os.FileInfo, err error) error {
 			// If you were called with an error, don't try to recover, just fail.
 			if err != nil {
 				return err
@@ -72,7 +72,7 @@ func testPath(dir string) func(t *testing.T) {
 			}
 
 			// Now trim the common prefix off.
-			newPath := strings.TrimPrefix(path, filepath.Join(base, dir)+"/")
+			newPath := strings.TrimPrefix(path, filepath.Join(testdata, dir)+"/")
 
 			if strings.HasSuffix(newPath, ".in") {
 				inputs = append(inputs, testtools.FileSpec{
@@ -97,7 +97,7 @@ func testPath(dir string) func(t *testing.T) {
 
 			return nil
 		}); err != nil {
-			t.Errorf("filepath.Walk(%q) error: %v", filepath.Join(base, dir), err)
+			t.Errorf("filepath.Walk(%q) error: %v", filepath.Join(testdata, dir), err)
 		}
 
 		dir, cleanup := testtools.CreateFiles(t, inputs)
diff --git a/gazelle/testdata/private/BUILD.out b/gazelle/testdata/private/BUILD.out
index 5709f874..e65b00f8 100644
--- a/gazelle/testdata/private/BUILD.out
+++ b/gazelle/testdata/private/BUILD.out
@@ -4,5 +4,5 @@ bzl_library(
     name = "foo",
     srcs = ["foo.bzl"],
     visibility = ["//visibility:public"],
-    deps = ["//nested/private:bar"],
+    deps = ["//private:bar"],
 )
diff --git a/gazelle/testdata/private/foo.bzl b/gazelle/testdata/private/foo.bzl
index bf33a05c..7e1dcd1f 100644
--- a/gazelle/testdata/private/foo.bzl
+++ b/gazelle/testdata/private/foo.bzl
@@ -2,6 +2,6 @@
 Test sample code.
 """
 
-load("//nested/private:bar.bzl", "func")
+load("//private:bar.bzl", "func")
 
 func()
diff --git a/gazelle/testdata/private/nested/private/BUILD.out b/gazelle/testdata/private/private/BUILD.out
similarity index 100%
rename from gazelle/testdata/private/nested/private/BUILD.out
rename to gazelle/testdata/private/private/BUILD.out
diff --git a/gazelle/testdata/private/nested/private/bar.bzl b/gazelle/testdata/private/private/bar.bzl
similarity index 100%
rename from gazelle/testdata/private/nested/private/bar.bzl
rename to gazelle/testdata/private/private/bar.bzl

From 990d75932a3b53dc6586d4b2cdad379d1ba29b5f Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 19:57:04 +0000
Subject: [PATCH 6/9] Make error output better

---
 gazelle/gazelle_test.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
index f3f63145..bb501be6 100644
--- a/gazelle/gazelle_test.go
+++ b/gazelle/gazelle_test.go
@@ -41,7 +41,7 @@ func TestGazelleBinary(t *testing.T) {
 	}
 	ds, err := ioutil.ReadDir(testdata)
 	if err != nil {
-		t.Errorf("ioutil.ReadDir(%q) error: %v", base, err)
+		t.Errorf("ioutil.ReadDir(%q) error: %v", testdata, err)
 	}
 	for _, d := range ds {
 		if d.IsDir() {

From 760a9dc8e3ba113d0664313faa510572e883029f Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 20:06:08 +0000
Subject: [PATCH 7/9] Try another way of doing runfiles

This might make windows work?
---
 gazelle/gazelle_test.go | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
index bb501be6..73d5ee33 100644
--- a/gazelle/gazelle_test.go
+++ b/gazelle/gazelle_test.go
@@ -29,19 +29,18 @@ import (
 
 var gazellePath = findGazelle()
 
-const base = "gazelle/testdata"
-
 // TestGazelleBinary runs a gazelle binary with starlib installed on each
 // directory in `testdata/*`. Please see `testdata/README.md` for more
 // information on each test.
 func TestGazelleBinary(t *testing.T) {
-	testdata, err := bazel.Runfile(base)
+	runfilesPath, err := bazel.RunfilesPath()
 	if err != nil {
-		t.Errorf("bazel.Runfile(%q) error: %v", base, err)
+		t.Fatalf("bazel.RunfilesPath() error: %v", err)
 	}
+	testdata := filepath.Join(runfilesPath, "gazelle", "testdata")
 	ds, err := ioutil.ReadDir(testdata)
 	if err != nil {
-		t.Errorf("ioutil.ReadDir(%q) error: %v", testdata, err)
+		t.Fatalf("ioutil.ReadDir(%q) error: %v", testdata, err)
 	}
 	for _, d := range ds {
 		if d.IsDir() {

From a1575d87a35b49c633780cd0085eb3579b12d522 Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Tue, 9 Jun 2020 20:24:28 +0000
Subject: [PATCH 8/9] One more try for windows

---
 gazelle/gazelle.go              | 61 ++++++++++++++++-------------
 gazelle/gazelle_test.go         | 68 ++++++++++++++++++---------------
 gazelle/testdata/empty/BUILD.in |  6 +++
 3 files changed, 78 insertions(+), 57 deletions(-)

diff --git a/gazelle/gazelle.go b/gazelle/gazelle.go
index ec3edc6e..b45ef3d8 100644
--- a/gazelle/gazelle.go
+++ b/gazelle/gazelle.go
@@ -203,30 +203,31 @@ func (*bzlLibraryLang) GenerateRules(args language.GenerateArgs) language.Genera
 	var rules []*rule.Rule
 	var imports []interface{}
 	for _, f := range append(args.RegularFiles, args.GenFiles...) {
-		if isBzlSourceFile(f) {
-			name := strings.TrimSuffix(f, fileType)
-			r := rule.NewRule("bzl_library", name)
-
-			r.SetAttr("srcs", []string{f})
+		if !isBzlSourceFile(f) {
+			continue
+		}
+		name := strings.TrimSuffix(f, fileType)
+		r := rule.NewRule("bzl_library", name)
 
-			if args.File == nil || !args.File.HasDefaultVisibility() {
-				inPrivateDir := pathtools.Index(args.Rel, "private") >= 0
-				if !inPrivateDir {
-					r.SetAttr("visibility", []string{"//visibility:public"})
-				}
-			}
+		r.SetAttr("srcs", []string{f})
 
-			fullPath := filepath.Join(args.Dir, f)
-			loads, err := getBzlFileLoads(fullPath)
-			if err != nil {
-				log.Printf("%s: contains syntax errors: %v", fullPath, err)
-				// Don't `continue` since it is reasonable to create a target even
-				// without deps.
+		if args.File == nil || !args.File.HasDefaultVisibility() {
+			inPrivateDir := pathtools.Index(args.Rel, "private") >= 0
+			if !inPrivateDir {
+				r.SetAttr("visibility", []string{"//visibility:public"})
 			}
+		}
 
-			rules = append(rules, r)
-			imports = append(imports, loads)
+		fullPath := filepath.Join(args.Dir, f)
+		loads, err := getBzlFileLoads(fullPath)
+		if err != nil {
+			log.Printf("%s: contains syntax errors: %v", fullPath, err)
+			// Don't `continue` since it is reasonable to create a target even
+			// without deps.
 		}
+
+		rules = append(rules, r)
+		imports = append(imports, loads)
 	}
 
 	return language.GenerateResult{
@@ -278,20 +279,26 @@ func generateEmpty(args language.GenerateArgs) []*rule.Rule {
 			continue
 		}
 		name := r.AttrString("name")
-		srcs := srcsList(r.AttrStrings("srcs"))
 
+		exists := make(map[string]bool)
 		for _, f := range args.RegularFiles {
-			if srcs.Contains(f) {
-				continue
-			}
+			exists[f] = true
 		}
 		for _, f := range args.GenFiles {
-			if srcs.Contains(f) {
-				continue
+			exists[f] = true
+		}
+		for _, r := range args.File.Rules {
+			srcsExist := false
+			for _, f := range r.AttrStrings("srcs") {
+				if exists[f] {
+					srcsExist = true
+					break
+				}
+			}
+			if !srcsExist {
+				ret = append(ret, rule.NewRule("bzl_library", name))
 			}
 		}
-
-		ret = append(ret, rule.NewRule("bzl_library", name))
 	}
 	return ret
 }
diff --git a/gazelle/gazelle_test.go b/gazelle/gazelle_test.go
index 73d5ee33..a22f7f65 100644
--- a/gazelle/gazelle_test.go
+++ b/gazelle/gazelle_test.go
@@ -29,74 +29,82 @@ import (
 
 var gazellePath = findGazelle()
 
+const testDataPath = "gazelle/testdata/"
+
 // TestGazelleBinary runs a gazelle binary with starlib installed on each
 // directory in `testdata/*`. Please see `testdata/README.md` for more
 // information on each test.
 func TestGazelleBinary(t *testing.T) {
-	runfilesPath, err := bazel.RunfilesPath()
-	if err != nil {
-		t.Fatalf("bazel.RunfilesPath() error: %v", err)
-	}
-	testdata := filepath.Join(runfilesPath, "gazelle", "testdata")
-	ds, err := ioutil.ReadDir(testdata)
+	tests := map[string][]bazel.RunfileEntry{}
+
+	files, err := bazel.ListRunfiles()
 	if err != nil {
-		t.Fatalf("ioutil.ReadDir(%q) error: %v", testdata, err)
+		t.Fatalf("bazel.ListRunfiles() error: %v", err)
 	}
-	for _, d := range ds {
-		if d.IsDir() {
-			t.Run(d.Name(), testPath(testdata, d.Name()))
+	for _, f := range files {
+		if strings.HasPrefix(f.ShortPath, testDataPath) {
+			relativePath := strings.TrimPrefix(f.ShortPath, testDataPath)
+			parts := strings.SplitN(relativePath, "/", 2)
+			if len(parts) < 2 {
+				// This file is not a part of a testcase since it must be in a dir that
+				// is the test case and then have a path inside of that.
+				continue
+			}
+
+			tests[parts[0]] = append(tests[parts[0]], f)
 		}
 	}
+
+	for testName, files := range tests {
+		testPath(t, testName, files)
+	}
 }
 
-func testPath(testdata string, dir string) func(t *testing.T) {
-	return func(t *testing.T) {
+func testPath(t *testing.T, name string, files []bazel.RunfileEntry) {
+	t.Run(name, func(t *testing.T) {
 		var inputs []testtools.FileSpec
 		var goldens []testtools.FileSpec
 
-		if err := filepath.Walk(filepath.Join(testdata, dir), func(path string, info os.FileInfo, err error) error {
-			// If you were called with an error, don't try to recover, just fail.
+		for _, f := range files {
+			path := f.Path
+			trim := testDataPath + name + "/"
+			shortPath := strings.TrimPrefix(f.ShortPath, trim)
+			info, err := os.Stat(path)
 			if err != nil {
-				return err
+				t.Fatalf("os.Stat(%q) error: %v", path, err)
 			}
 
 			// Skip dirs.
 			if info.IsDir() {
-				return nil
+				continue
 			}
 
 			content, err := ioutil.ReadFile(path)
 			if err != nil {
-				return err
+				t.Errorf("ioutil.ReadFile(%q) error: %v", path, err)
 			}
 
 			// Now trim the common prefix off.
-			newPath := strings.TrimPrefix(path, filepath.Join(testdata, dir)+"/")
-
-			if strings.HasSuffix(newPath, ".in") {
+			if strings.HasSuffix(shortPath, ".in") {
 				inputs = append(inputs, testtools.FileSpec{
-					Path:    strings.TrimSuffix(newPath, ".in"),
+					Path:    strings.TrimSuffix(shortPath, ".in"),
 					Content: string(content),
 				})
-			} else if strings.HasSuffix(newPath, ".out") {
+			} else if strings.HasSuffix(shortPath, ".out") {
 				goldens = append(goldens, testtools.FileSpec{
-					Path:    strings.TrimSuffix(newPath, ".out"),
+					Path:    strings.TrimSuffix(shortPath, ".out"),
 					Content: string(content),
 				})
 			} else {
 				inputs = append(inputs, testtools.FileSpec{
-					Path:    newPath,
+					Path:    shortPath,
 					Content: string(content),
 				})
 				goldens = append(goldens, testtools.FileSpec{
-					Path:    newPath,
+					Path:    shortPath,
 					Content: string(content),
 				})
 			}
-
-			return nil
-		}); err != nil {
-			t.Errorf("filepath.Walk(%q) error: %v", filepath.Join(testdata, dir), err)
 		}
 
 		dir, cleanup := testtools.CreateFiles(t, inputs)
@@ -120,7 +128,7 @@ func testPath(testdata string, dir string) func(t *testing.T) {
 				return nil
 			})
 		}
-	}
+	})
 }
 
 func findGazelle() string {
diff --git a/gazelle/testdata/empty/BUILD.in b/gazelle/testdata/empty/BUILD.in
index 80690c9e..e1e154cb 100644
--- a/gazelle/testdata/empty/BUILD.in
+++ b/gazelle/testdata/empty/BUILD.in
@@ -1,5 +1,11 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
 
+bzl_library(
+    name = "weirdly_named_target_that_will_be_removed",
+    srcs = ["nonexistant.bzl"],
+    visibility = ["//visibility:public"],
+)
+
 bzl_library(
     name = "weirdly_named_target_that_will_be_renamed",
     srcs = ["foo.bzl"],

From 5da107a17525608134249f55901f972d651c3a9e Mon Sep 17 00:00:00 2001
From: Andrew Allen <achew@stairwell.com>
Date: Wed, 24 Jun 2020 22:44:30 +0000
Subject: [PATCH 9/9] Fix lint error

---
 BUILD | 1 +
 1 file changed, 1 insertion(+)

diff --git a/BUILD b/BUILD
index ad1dbfb8..bec32f56 100644
--- a/BUILD
+++ b/BUILD
@@ -6,6 +6,7 @@ package(default_visibility = ["//visibility:public"])
 
 # gazelle:exclude internal_deps.bzl
 # gazelle:exclude internal_setup.bzl
+# buildifier: disable=skylark-comment
 # gazelle:exclude skylark_library.bzl
 
 exports_files(["LICENSE"])