Add a systemModules utility type

Storing system modules in a classpath is clumsy, as there should
only ever be one system modules, and it needs to store both a
directory to pass as the argument and a set of generated files
to use as dependencies.  Store them in a separate systemModules
type instead.

Test: m checkbuild
Change-Id: I020556c736bd5091865bcca51dc0fb9e4db6b45b

java/builder.go

@@ -148,16 +148,15 @@ func init() {
 }
 
 type javaBuilderFlags struct {
-	javacFlags        string
-	bootClasspath     classpath
-	classpath         classpath
-	processorPath     classpath
-	processor         string
-	systemModules     classpath
-	systemModulesDeps android.Paths
-	aidlFlags         string
-	aidlDeps          android.Paths
-	javaVersion       string
+	javacFlags    string
+	bootClasspath classpath
+	classpath     classpath
+	processorPath classpath
+	processor     string
+	systemModules *systemModules
+	aidlFlags     string
+	aidlDeps      android.Paths
+	javaVersion   string
 
 	errorProneExtraJavacFlags string
 	errorProneProcessorPath   classpath
@@ -249,8 +248,9 @@ func transformJavaToClasses(ctx android.ModuleContext, outputFile android.Writab
 
 	var bootClasspath string
 	if flags.javaVersion == "1.9" {
-		deps = append(deps, flags.systemModulesDeps...)
-		bootClasspath = flags.systemModules.FormJavaSystemModulesPath("--system=", ctx.Device())
+		var systemModuleDeps android.Paths
+		bootClasspath, systemModuleDeps = flags.systemModules.FormJavaSystemModulesPath(ctx.Device())
+		deps = append(deps, systemModuleDeps...)
 	} else {
 		deps = append(deps, flags.bootClasspath...)
 		if len(flags.bootClasspath) == 0 && ctx.Device() {
@@ -424,21 +424,6 @@ func (x *classpath) FormJavaClassPath(optName string) 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) FormJavaSystemModulesPath(optName string, forceEmpty bool) string {
-	if len(*x) > 1 {
-		panic("more than one system module")
-	} else if len(*x) == 1 {
-		return optName + (*x)[0].String()
-	} else if forceEmpty {
-		return optName + "none"
-	} else {
-		return ""
-	}
-}
-
 func (x *classpath) FormTurbineClasspath(optName string) []string {
 	if x == nil || *x == nil {
 		return nil
@@ -466,3 +451,21 @@ func (x *classpath) Strings() []string {
 	}
 	return ret
 }
+
+type systemModules struct {
+	dir  android.Path
+	deps android.Paths
+}
+
+// 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 *systemModules) FormJavaSystemModulesPath(forceEmpty bool) (string, android.Paths) {
+	if x != nil {
+		return "--system=" + x.dir.String(), x.deps
+	} else if forceEmpty {
+		return "--system=none", nil
+	} else {
+		return "", nil
+	}
+}

java/droiddoc.go

@@ -636,8 +636,7 @@ func (j *Javadoc) collectDeps(ctx android.ModuleContext) deps {
 			if sm.outputDir == nil && len(sm.outputDeps) == 0 {
 				panic("Missing directory for system module dependency")
 			}
-			deps.systemModules = sm.outputDir
-			deps.systemModulesDeps = sm.outputDeps
+			deps.systemModules = &systemModules{sm.outputDir, sm.outputDeps}
 		}
 	})
 	// do not pass exclude_srcs directly when expanding srcFiles since exclude_srcs
@@ -714,13 +713,10 @@ func (j *Javadoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 
 	javaVersion := getJavaVersion(ctx, String(j.properties.Java_version), sdkContext(j))
 	if len(deps.bootClasspath) > 0 {
-		var systemModules classpath
-		if deps.systemModules != nil {
-			systemModules = append(systemModules, deps.systemModules)
-		}
-		implicits = append(implicits, deps.systemModulesDeps...)
-		bootClasspathArgs = systemModules.FormJavaSystemModulesPath("--system ", ctx.Device())
+		var systemModulesDeps android.Paths
+		bootClasspathArgs, systemModulesDeps = deps.systemModules.FormJavaSystemModulesPath(ctx.Device())
 		bootClasspathArgs = bootClasspathArgs + " --patch-module java.base=."
+		implicits = append(implicits, systemModulesDeps...)
 	}
 	if len(deps.classpath.Strings()) > 0 {
 		classpathArgs = "-classpath " + strings.Join(deps.classpath.Strings(), ":")

java/java.go

@@ -632,8 +632,7 @@ type deps struct {
 	aidlIncludeDirs    android.Paths
 	srcs               android.Paths
 	srcJars            android.Paths
-	systemModules      android.Path
-	systemModulesDeps  android.Paths
+	systemModules      *systemModules
 	aidlPreprocess     android.OptionalPath
 	kotlinStdlib       android.Paths
 	kotlinAnnotations  android.Paths
@@ -844,8 +843,7 @@ func (j *Module) collectDeps(ctx android.ModuleContext) deps {
 				if sm.outputDir == nil || len(sm.outputDeps) == 0 {
 					panic("Missing directory for system module dependency")
 				}
-				deps.systemModules = sm.outputDir
-				deps.systemModulesDeps = sm.outputDeps
+				deps.systemModules = &systemModules{sm.outputDir, sm.outputDeps}
 			}
 		}
 	})
@@ -973,10 +971,7 @@ func (j *Module) collectBuilderFlags(ctx android.ModuleContext, deps deps) javaB
 	}
 
 	// systemModules
-	if deps.systemModules != nil {
-		flags.systemModules = append(flags.systemModules, deps.systemModules)
-		flags.systemModulesDeps = append(flags.systemModulesDeps, deps.systemModulesDeps...)
-	}
+	flags.systemModules = deps.systemModules
 
 	// aidl flags.
 	flags.aidlFlags, flags.aidlDeps = j.aidlFlags(ctx, deps.aidlPreprocess, deps.aidlIncludeDirs)