Prepend header jar for sharded javac compilation

When compiling without sharding javac will prefer classes built from
source over classes in the classpath.  Compiling with sharding puts
the header classes for all the sources onto the classpath, including
the sources that are not part of the current shard.  Emulate the
behavior when building without sharding by putting the header jar
first on the classpath so classes are resolved from the rest of
the sources before the real classpath.

Also switch to using the header jar without static libs dependencies
merged in, as those will already be present in the classpath.

Test: m framework-minus-apex
Test: m services.core
Test: TestSharding
Change-Id: Id11b39c15d89ce70da27d746a5c7e6b603c3c0f9

2 files changed, 14 insertions, 12 deletions

diff --git a/java/base.go b/java/base.go
index 71b5ac8e0..d9b126059 100644
--- a/java/base.go
+++ b/java/base.go
@@ -1066,7 +1066,7 @@ func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
 	j.compiledSrcJars = srcJars
 
 	enableSharding := false
-	var headerJarFileWithoutJarjar android.Path
+	var headerJarFileWithoutDepsOrJarjar android.Path
 	if ctx.Device() && !ctx.Config().IsEnvFalse("TURBINE_ENABLED") && !deps.disableTurbine {
 		if j.properties.Javac_shard_size != nil && *(j.properties.Javac_shard_size) > 0 {
 			enableSharding = true
@@ -1076,7 +1076,7 @@ func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
 			// allow for the use of annotation processors that do function correctly
 			// with sharding enabled. See: b/77284273.
 		}
-		headerJarFileWithoutJarjar, j.headerJarFile =
+		headerJarFileWithoutDepsOrJarjar, j.headerJarFile =
 			j.compileJavaHeader(ctx, uniqueSrcFiles, srcJars, deps, flags, jarName, kotlinJars)
 		if ctx.Failed() {
 			return
@@ -1105,7 +1105,9 @@ func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
 		}
 
 		if enableSharding {
-			flags.classpath = append(flags.classpath, headerJarFileWithoutJarjar)
+			if headerJarFileWithoutDepsOrJarjar != nil {
+				flags.classpath = append(classpath{headerJarFileWithoutDepsOrJarjar}, flags.classpath...)
+			}
 			shardSize := int(*(j.properties.Javac_shard_size))
 			var shardSrcs []android.Paths
 			if len(uniqueSrcFiles) > 0 {
@@ -1508,7 +1510,7 @@ func CheckKotlincFlags(ctx android.ModuleContext, flags []string) {
 
 func (j *Module) compileJavaHeader(ctx android.ModuleContext, srcFiles, srcJars android.Paths,
 	deps deps, flags javaBuilderFlags, jarName string,
-	extraJars android.Paths) (headerJar, jarjarHeaderJar android.Path) {
+	extraJars android.Paths) (headerJar, jarjarAndDepsHeaderJar android.Path) {
 
 	var jars android.Paths
 	if len(srcFiles) > 0 || len(srcJars) > 0 {
@@ -1519,6 +1521,7 @@ func (j *Module) compileJavaHeader(ctx android.ModuleContext, srcFiles, srcJars
 			return nil, nil
 		}
 		jars = append(jars, turbineJar)
+		headerJar = turbineJar
 	}
 
 	jars = append(jars, extraJars...)
@@ -1532,20 +1535,19 @@ func (j *Module) compileJavaHeader(ctx android.ModuleContext, srcFiles, srcJars
 	combinedJar := android.PathForModuleOut(ctx, "turbine-combined", jarName)
 	TransformJarsToJar(ctx, combinedJar, "for turbine", jars, android.OptionalPath{},
 		false, nil, []string{"META-INF/TRANSITIVE"})
-	headerJar = combinedJar
-	jarjarHeaderJar = combinedJar
+	jarjarAndDepsHeaderJar = combinedJar
 
 	if j.expandJarjarRules != nil {
 		// Transform classes.jar into classes-jarjar.jar
 		jarjarFile := android.PathForModuleOut(ctx, "turbine-jarjar", jarName)
-		TransformJarJar(ctx, jarjarFile, headerJar, j.expandJarjarRules)
-		jarjarHeaderJar = jarjarFile
+		TransformJarJar(ctx, jarjarFile, jarjarAndDepsHeaderJar, j.expandJarjarRules)
+		jarjarAndDepsHeaderJar = jarjarFile
 		if ctx.Failed() {
 			return nil, nil
 		}
 	}
 
-	return headerJar, jarjarHeaderJar
+	return headerJar, jarjarAndDepsHeaderJar
 }
 
 func (j *Module) instrument(ctx android.ModuleContext, flags javaBuilderFlags,
diff --git a/java/java_test.go b/java/java_test.go
index c039f7246..6e4e673ec 100644
--- a/java/java_test.go
+++ b/java/java_test.go
@@ -988,11 +988,11 @@ func TestSharding(t *testing.T) {
 		}
 		`)
 
-	barHeaderJar := filepath.Join("out", "soong", ".intermediates", "bar", "android_common", "turbine-combined", "bar.jar")
+	barHeaderJar := filepath.Join("out", "soong", ".intermediates", "bar", "android_common", "turbine", "bar.jar")
 	for i := 0; i < 3; i++ {
 		barJavac := ctx.ModuleForTests("bar", "android_common").Description("javac" + strconv.Itoa(i))
-		if !strings.Contains(barJavac.Args["classpath"], barHeaderJar) {
-			t.Errorf("bar javac classpath %v does not contain %q", barJavac.Args["classpath"], barHeaderJar)
+		if !strings.HasPrefix(barJavac.Args["classpath"], "-classpath "+barHeaderJar+":") {
+			t.Errorf("bar javac classpath %v does start with %q", barJavac.Args["classpath"], barHeaderJar)
 		}
 	}
 }