1 files changed, 54 insertions, 0 deletions
diff --git a/java/tracereferences.go b/java/tracereferences.go
new file mode 100644
index 000000000..342b6a630
--- /dev/null
+++ b/java/tracereferences.go
@@ -0,0 +1,54 @@
+// Copyright 2025 Google Inc. 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 java
+
+import (
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+)
+
+var traceReferences = pctx.AndroidStaticRule("traceReferences",
+	blueprint.RuleParams{
+		Command: `${config.TraceReferencesCmd} ` +
+			// Note that we suppress missing def errors, as we're only interested
+			// in the direct deps between the sources and target.
+			`--map-diagnostics:MissingDefinitionsDiagnostic error none ` +
+			`--keep-rules ` +
+			`--output ${out} ` +
+			`--target ${in} ` +
+			// `--source` and `--lib` are already prepended to each
+			// jar reference in the sources and libs joined string args.
+			`${sources} ` +
+			`${libs}`,
+		CommandDeps: []string{"${config.TraceReferencesCmd}"},
+	}, "sources", "libs")
+
+// Generates keep rules in output corresponding to any references from sources
+// (a list of jars) onto target (the referenced jar) that are not included in
+// libs (a list of external jars).
+func TraceReferences(ctx android.ModuleContext, sources android.Paths, target android.Path, libs android.Paths,
+	output android.WritablePath) {
+	ctx.Build(pctx, android.BuildParams{
+		Rule:      traceReferences,
+		Input:     target,
+		Output:    output,
+		Implicits: append(sources, libs...),
+		Args: map[string]string{
+			"sources": android.JoinWithPrefix(sources.Strings(), "--source "),
+			"libs":    android.JoinWithPrefix(libs.Strings(), "--lib "),
+		},
+	})
+}