Initial support for converting jars to java9 system modules

Adds a java_system_modules module type that (when
EXPERIMENTAL_USE_OPENJDK9 is set to true) converts a list of
java library modules and prebuilt jars into system modules,
and plumbs the system modules through to the javac command
line.

Also exports the location of the system modules to make
variables, as well as the name of the default system module.

Test: TestClasspath in java_test.go, runs automatically as part of the build
Bug: 63986449
Change-Id: I27bd5d2010092422a27b69c91568e49010e02f40

1 files changed, 28 insertions, 3 deletions

diff --git a/java/builder.go b/java/builder.go
index 118f23979..8992f681a 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -126,6 +126,7 @@ type javaBuilderFlags struct {
 	dxFlags       string
 	bootClasspath classpath
 	classpath     classpath
+	systemModules classpath
 	desugarFlags  string
 	aidlFlags     string
 	javaVersion   string
@@ -177,7 +178,16 @@ func transformJavaToClasses(ctx android.ModuleContext, srcFiles, srcFileLists an
 	}
 
 	deps = append(deps, srcFileLists...)
-	deps = append(deps, flags.bootClasspath...)
+
+	var bootClasspath string
+	if flags.javaVersion == "1.9" {
+		deps = append(deps, flags.systemModules...)
+		bootClasspath = flags.systemModules.JavaSystemModules(ctx.Device())
+	} else {
+		deps = append(deps, flags.bootClasspath...)
+		bootClasspath = flags.bootClasspath.JavaBootClasspath(ctx.Device())
+	}
+
 	deps = append(deps, flags.classpath...)
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
@@ -188,7 +198,7 @@ func transformJavaToClasses(ctx android.ModuleContext, srcFiles, srcFileLists an
 		Implicits:   deps,
 		Args: map[string]string{
 			"javacFlags":    javacFlags,
-			"bootClasspath": flags.bootClasspath.JavaBootClasspath(ctx.Device()),
+			"bootClasspath": bootClasspath,
 			"classpath":     flags.classpath.JavaClasspath(),
 			"outDir":        android.PathForModuleOut(ctx, "classes"+suffix).String(),
 			"annoDir":       android.PathForModuleOut(ctx, "anno"+suffix).String(),
@@ -259,7 +269,7 @@ func TransformDesugar(ctx android.ModuleContext, classesJar android.Path,
 	dumpDir := android.PathForModuleOut(ctx, "desugar_dumped_classes")
 
 	javaFlags := ""
-	if ctx.AConfig().Getenv("EXPERIMENTAL_USE_OPENJDK9") != "" {
+	if ctx.AConfig().UseOpenJDK9() {
 		javaFlags = "--add-opens java.base/java.lang.invoke=ALL-UNNAMED"
 	}
 
@@ -359,6 +369,21 @@ func (x *classpath) JavaBootClasspath(forceEmpty bool) string {
 	}
 }
 
+// Returns a --system argument in the form javac expects with -source 1.9.  If forceEmpty is true,
+// returns --system=none if the list is empty to ensure javac does not fall back to the default
+// system modules.
+func (x *classpath) JavaSystemModules(forceEmpty bool) string {
+	if len(*x) > 1 {
+		panic("more than one system module")
+	} else if len(*x) == 1 {
+		return "--system=" + strings.TrimSuffix((*x)[0].String(), "lib/modules")
+	} else if forceEmpty {
+		return "--system=none"
+	} else {
+		return ""
+	}
+}
+
 func (x *classpath) DesugarBootClasspath() []string {
 	if x == nil || *x == nil {
 		return nil