Add gazelle:scala_sweep_transitive_deps (#139)

* Add gazelle:scala_sweep_transitive_deps

* Add gazelle:scala_keep_unknown_deps

* Improve log output

* github actions: upgrade to cache v4

* upgrade to bazelbuild/setup-bazelisk@v3

Author: pcj

.github/workflows/ci.yaml

@@ -20,7 +20,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
-      - uses: bazelbuild/setup-bazelisk@v2
+      - uses: bazelbuild/setup-bazelisk@v3
 
       - name: Mount bazel action cache
         uses: actions/cache@v4

.github/workflows/format.yaml

@@ -20,7 +20,7 @@ jobs:
     steps:
       - uses: actions/checkout@v3
 
-      - uses: bazelbuild/setup-bazelisk@v2
+      - uses: bazelbuild/setup-bazelisk@v3
 
       - name: Mount bazel action cache
         uses: actions/cache@v2

language/scala/existing_scala_rule.go

@@ -6,10 +6,13 @@ import (
 	"strings"
 
 	"github.com/bazelbuild/bazel-gazelle/config"
+	"github.com/bazelbuild/bazel-gazelle/label"
 	"github.com/bazelbuild/bazel-gazelle/resolve"
 	"github.com/bazelbuild/bazel-gazelle/rule"
 	"github.com/bazelbuild/buildtools/build"
 
+	"github.com/stackb/scala-gazelle/pkg/bazel"
+	"github.com/stackb/scala-gazelle/pkg/collections"
 	"github.com/stackb/scala-gazelle/pkg/protobuf"
 	"github.com/stackb/scala-gazelle/pkg/scalaconfig"
 	"github.com/stackb/scala-gazelle/pkg/scalarule"
@@ -153,6 +156,72 @@ func (s *existingScalaRule) Resolve(rctx *scalarule.ResolveContext, importsRaw i
 		sc.Exports(exports, rctx.Rule, "exports", rctx.From)
 	}
 
+	if sc.ShouldSweepTransitiveDeps() {
+		if err := s.sweepTransitive("deps", rctx.Rule, rctx.From); err != nil {
+			log.Panicf("transitive sweep failed: %v", err)
+		}
+	}
+
+}
+
+// sweepTransitive iterates through deps marked "TRANSITIVE" and removes them if
+// the target still builds without it.
+func (s *existingScalaRule) sweepTransitive(attrName string, r *rule.Rule, from label.Label) error {
+	expr := r.Attr(attrName)
+	if expr == nil {
+		return nil
+	}
+
+	deps, isList := expr.(*build.ListExpr)
+	if !isList {
+		return nil // some other condition we can't deal with
+	}
+
+	file := s.pkg.GenerateArgs().File
+
+	// target should build first time, otherwise we can't check accurately.
+	log.Println("🧱 transitive sweep:", from)
+
+	if out, exitCode, _ := bazel.ExecCommand("bazel", "build", from.String()); exitCode != 0 {
+		log.Fatalln("sweep failed (must build cleanly on first attempt): %s", string(out))
+	}
+
+	for i := len(deps.List) - 1; i >= 0; i-- {
+		expr := deps.List[i]
+		switch t := expr.(type) {
+		case *build.StringExpr:
+			if len(t.Comments.Suffix) != 1 {
+				continue
+			}
+			if t.Comments.Suffix[0].Token != "# TRANSITIVE" {
+				continue
+			}
+
+			dep, err := label.Parse(t.Value)
+			if err != nil {
+				return err
+			}
+			deps.List = collections.SliceRemoveIndex(deps.List, i)
+
+			if err := file.Save(file.Path); err != nil {
+				return err
+			}
+
+			if _, exitCode, _ := bazel.ExecCommand("bazel", "build", from.String()); exitCode == 0 {
+				log.Println("- 💩 junk:", dep)
+			} else {
+				log.Println("- 👑 keep:", dep)
+				deps.List = collections.SliceInsertAt(deps.List, i, expr)
+			}
+		}
+
+	}
+
+	if err := file.Save(file.Path); err != nil {
+		return err
+	}
+
+	return nil
 }
 
 func makeRuleComments(pb *sppb.Rule) (comments []build.Comment) {

language/scala/language_test.go

@@ -23,6 +23,8 @@ func ExampleLanguage_KnownDirectives() {
 	// scala_debug
 	// scala_log_level
 	// scala_deps_cleaner
+	// scala_keep_unknown_deps
+	// scala_sweep_transitive_deps
 	// scala_fix_wildcard_imports
 	// scala_generate_build_files
 	// scala_rule

language/scala/package_marker_rule.go

@@ -5,13 +5,15 @@ import (
 	"github.com/pcj/mobyprogress"
 )
 
-const packageMarkerRuleKind = "_package_marker"
+const packageMarkerRuleKind = "filegroup"
+const packageMarkerRuleName = "package_marker"
 
 // generatePackageMarkerRule creates a dummy rule that forces gazelle to run the
 // resolve phase at least once per package; used for tracking progress during
 // the resolve phase.
 func generatePackageMarkerRule(pkgNum int, pkg *scalaPackage) *rule.Rule {
-	r := rule.NewRule(packageMarkerRuleKind, packageMarkerRuleKind)
+	r := rule.NewRule(packageMarkerRuleKind, packageMarkerRuleName)
+	r.SetAttr("srcs", []string{})
 	r.SetPrivateAttr("n", pkgNum)
 	r.SetPrivateAttr("pkg", pkg)
 	return r

language/scala/testdata/maven_provider/BUILD.in

@@ -3,14 +3,16 @@ load("@io_bazel_rules_scala//scala:scala.bzl", "scala_library")
 # gazelle:scala_rule scala_library implementation @io_bazel_rules_scala//scala:scala.bzl%scala_library
 # gazelle:scala_debug imports dep_label_origin
 # gazelle:resolve_with scala javax.xml._ javax.inject
+# gazelle:scala_keep_unknown_deps true
 
 scala_library(
     name = "app",
     srcs = ["Main.scala"],
     deps = [
         # junit is required for compilation but we haven't specified
         # that @atlassian-public deps should be managed by the scala-gazelle
-        # extension (so this is left alone despite no # keep directive)
+        # extension (this is left alone despite no # keep directive because of
+        # scala_keep_unknown_deps)
         "@atlassian-public//:junit_junit",
     ],
 )

language/scala/testdata/maven_provider/BUILD.out

@@ -3,6 +3,7 @@ load("@io_bazel_rules_scala//scala:scala.bzl", "scala_library")
 # gazelle:scala_rule scala_library implementation @io_bazel_rules_scala//scala:scala.bzl%scala_library
 # gazelle:scala_debug imports dep_label_origin
 # gazelle:resolve_with scala javax.xml._ javax.inject
+# gazelle:scala_keep_unknown_deps true
 
 scala_library(
     name = "app",
@@ -13,7 +14,8 @@ scala_library(
     deps = [
         # junit is required for compilation but we haven't specified
         # that @atlassian-public deps should be managed by the scala-gazelle
-        # extension (so this is left alone despite no # keep directive)
+        # extension (this is left alone despite no # keep directive because of
+        # scala_keep_unknown_deps)
         "@atlassian-public//:junit_junit",
         "@maven//:javax_inject_javax_inject",  # IMPLICIT (maven javax.inject <filename unknown>)
         "@maven//:xml_apis_xml_apis",  # DIRECT (maven javax.xml Main.scala)

pkg/bazel/bazel.go

@@ -1,7 +1,6 @@
 package bazel
 
 import (
-	"log"
 	"os"
 	"os/exec"
 	"path"
@@ -33,13 +32,13 @@ func NewTmpDir(prefix string) (string, error) {
 	return os.MkdirTemp("", prefix)
 }
 
-func ExecCommand(bazelExe, command, label string) ([]byte, int, error) {
-	args := []string{command, label}
+func ExecCommand(bazelExe, command string, labels ...string) ([]byte, int, error) {
+	args := append([]string{command}, labels...)
 
 	cmd := exec.Command(bazelExe, args...)
 	cmd.Dir = GetBuildWorkspaceDirectory()
 
-	log.Println("🧱", cmd.String())
+	// log.Println("🧱", cmd.String())
 	output, err := cmd.CombinedOutput()
 	exitCode := procutil.CmdExitCode(cmd, err)
 

pkg/collections/BUILD.bazel

@@ -11,6 +11,7 @@ go_library(
         "net.go",
         "path_trie.go",
         "sha256.go",
+        "slice.go",
         "string_slice.go",
         "string_stack.go",
         "uint32stack.go",
@@ -31,6 +32,7 @@ package_filegroup(
         "net.go",
         "path_trie.go",
         "sha256.go",
+        "slice.go",
         "string_slice.go",
         "string_stack.go",
         "uint32stack.go",

pkg/collections/slice.go

@@ -0,0 +1,28 @@
+package collections
+
+func SliceRemoveIndex[T any](slice []T, i int) []T {
+	// Create a new slice with capacity one less than original
+	result := make([]T, 0, len(slice)-1)
+
+	// Add all elements except the one at index i
+	result = append(result, slice[:i]...)
+	result = append(result, slice[i+1:]...)
+
+	return result
+}
+
+func SliceInsertAt[T any](slice []T, i int, value T) []T {
+	// Create a new slice with capacity one more than original
+	result := make([]T, 0, len(slice)+1)
+
+	// Add elements before index i
+	result = append(result, slice[:i]...)
+
+	// Add the new value
+	result = append(result, value)
+
+	// Add elements after index i
+	result = append(result, slice[i:]...)
+
+	return result
+}