Provide a reasonable warning message when a directory artifact crosse…

…s a package boundary.

We probably shouldn't cross package boundaries when collecting these entries in the first place, but we might as well put lipstick on this pig.

Closes bazelbuild#12527

PiperOrigin-RevId: 346344693

src/main/java/com/google/devtools/build/lib/skyframe/ArtifactFunction.java

@@ -282,13 +282,14 @@ private static SkyValue createSourceValue(Artifact artifact, Environment env)
       //
       // In the future, we need to make this result the source of truth for the files available to
       // the action so that we at least have consistency.
-      TraversalRequest request = TraversalRequest.create(
-          DirectTraversalRoot.forRootedPath(path),
-          /*isRootGenerated=*/ false,
-          PackageBoundaryMode.CROSS,
-          /*strictOutputFiles=*/ true,
-          /*skipTestingForSubpackage=*/ true,
-          /*errorInfo=*/ null);
+      TraversalRequest request =
+          TraversalRequest.create(
+              DirectTraversalRoot.forRootedPath(path),
+              /*isRootGenerated=*/ false,
+              PackageBoundaryMode.CROSS,
+              /*strictOutputFiles=*/ true,
+              /*skipTestingForSubpackage=*/ true,
+              /*errorInfo=*/ "Directory artifact " + artifact.prettyPrint());
       RecursiveFilesystemTraversalValue value;
       try {
         value =

src/test/shell/integration/execution_phase_tests.sh

@@ -384,4 +384,13 @@ function test_resource_flags_syntax() {
       || fail "Empty build failed"
 }
 
+function test_track_directory_crossing_package() {
+  mkdir -p foo/dir/subdir
+  touch foo/dir/subdir/BUILD
+  echo "filegroup(name = 'foo', srcs = ['dir'])" > foo/BUILD
+  bazel --host_jvm_args=-DBAZEL_TRACK_SOURCE_DIRECTORIES=1 build //foo \
+      >& "$TEST_log" || fail "Expected success"
+  expect_log "WARNING: Directory artifact foo/dir crosses package boundary into"
+}
+
 run_suite "Integration tests of ${PRODUCT_NAME} using the execution phase."