Merge changes Icbbf176c,I52beadc8

* changes:
  rust: Add ref to generated sources (aidl, bindgen)
  rust: refactor projectGeneratorSingleton
diff --git a/rust/project_json.go b/rust/project_json.go
index 8310479..8d161b2 100644
--- a/rust/project_json.go
+++ b/rust/project_json.go
@@ -30,16 +30,6 @@
 //
 //   $ SOONG_GEN_RUST_PROJECT=1 m nothing
 
-func init() {
-	android.RegisterSingletonType("rust_project_generator", rustProjectGeneratorSingleton)
-}
-
-func rustProjectGeneratorSingleton() android.Singleton {
-	return &projectGeneratorSingleton{}
-}
-
-type projectGeneratorSingleton struct{}
-
 const (
 	// Environment variables used to control the behavior of this singleton.
 	envVariableCollectRustDeps = "SOONG_GEN_RUST_PROJECT"
@@ -49,6 +39,7 @@
 // The format of rust-project.json is not yet finalized. A current description is available at:
 // https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/manual.adoc#non-cargo-based-projects
 type rustProjectDep struct {
+	// The Crate attribute is the index of the dependency in the Crates array in rustProjectJson.
 	Crate int    `json:"crate"`
 	Name  string `json:"name"`
 }
@@ -71,12 +62,50 @@
 	Deps map[string]int
 }
 
-func mergeDependencies(ctx android.SingletonContext, project *rustProjectJson,
-	knownCrates map[string]crateInfo, module android.Module,
-	crate *rustProjectCrate, deps map[string]int) {
+type projectGeneratorSingleton struct {
+	project     rustProjectJson
+	knownCrates map[string]crateInfo
+}
+
+func rustProjectGeneratorSingleton() android.Singleton {
+	return &projectGeneratorSingleton{}
+}
+
+func init() {
+	android.RegisterSingletonType("rust_project_generator", rustProjectGeneratorSingleton)
+}
+
+// librarySource finds the main source file (.rs) for a crate.
+func librarySource(ctx android.SingletonContext, rModule *Module, rustLib *libraryDecorator) (string, bool) {
+	srcs := rustLib.baseCompiler.Properties.Srcs
+	if len(srcs) != 0 {
+		return path.Join(ctx.ModuleDir(rModule), srcs[0]), true
+	}
+	if !rustLib.source() {
+		return "", false
+	}
+	// It is a SourceProvider module. If this module is host only, uses the variation for the host.
+	// Otherwise, use the variation for the primary target.
+	switch rModule.hod {
+	case android.HostSupported:
+	case android.HostSupportedNoCross:
+		if rModule.Target().String() != ctx.Config().BuildOSTarget.String() {
+			return "", false
+		}
+	default:
+		if rModule.Target().String() != ctx.Config().Targets[android.Android][0].String() {
+			return "", false
+		}
+	}
+	src := rustLib.sourceProvider.Srcs()[0]
+	return src.String(), true
+}
+
+func (singleton *projectGeneratorSingleton) mergeDependencies(ctx android.SingletonContext,
+	module android.Module, crate *rustProjectCrate, deps map[string]int) {
 
 	ctx.VisitDirectDeps(module, func(child android.Module) {
-		childId, childCrateName, ok := appendLibraryAndDeps(ctx, project, knownCrates, child)
+		childId, childCrateName, ok := singleton.appendLibraryAndDeps(ctx, child)
 		if !ok {
 			return
 		}
@@ -88,12 +117,10 @@
 	})
 }
 
-// appendLibraryAndDeps creates a rustProjectCrate for the module argument and
-// appends it to the rustProjectJson struct.  It visits the dependencies of the
-// module depth-first. If the current module is already in knownCrates, its
-// dependencies are merged. Returns a tuple (id, crate_name, ok).
-func appendLibraryAndDeps(ctx android.SingletonContext, project *rustProjectJson,
-	knownCrates map[string]crateInfo, module android.Module) (int, string, bool) {
+// appendLibraryAndDeps creates a rustProjectCrate for the module argument and appends it to singleton.project.
+// It visits the dependencies of the module depth-first so the dependency ID can be added to the current module. If the
+// current module is already in singleton.knownCrates, its dependencies are merged. Returns a tuple (id, crate_name, ok).
+func (singleton *projectGeneratorSingleton) appendLibraryAndDeps(ctx android.SingletonContext, module android.Module) (int, string, bool) {
 	rModule, ok := module.(*Module)
 	if !ok {
 		return 0, "", false
@@ -107,46 +134,45 @@
 	}
 	moduleName := ctx.ModuleName(module)
 	crateName := rModule.CrateName()
-	if cInfo, ok := knownCrates[moduleName]; ok {
+	if cInfo, ok := singleton.knownCrates[moduleName]; ok {
 		// We have seen this crate already; merge any new dependencies.
-		crate := project.Crates[cInfo.ID]
-		mergeDependencies(ctx, project, knownCrates, module, &crate, cInfo.Deps)
-		project.Crates[cInfo.ID] = crate
+		crate := singleton.project.Crates[cInfo.ID]
+		singleton.mergeDependencies(ctx, module, &crate, cInfo.Deps)
+		singleton.project.Crates[cInfo.ID] = crate
 		return cInfo.ID, crateName, true
 	}
 	crate := rustProjectCrate{Deps: make([]rustProjectDep, 0), Cfgs: make([]string, 0)}
-	srcs := rustLib.baseCompiler.Properties.Srcs
-	if len(srcs) == 0 {
+	rootModule, ok := librarySource(ctx, rModule, rustLib)
+	if !ok {
 		return 0, "", false
 	}
-	crate.RootModule = path.Join(ctx.ModuleDir(rModule), srcs[0])
+	crate.RootModule = rootModule
 	crate.Edition = rustLib.baseCompiler.edition()
 
 	deps := make(map[string]int)
-	mergeDependencies(ctx, project, knownCrates, module, &crate, deps)
+	singleton.mergeDependencies(ctx, module, &crate, deps)
 
-	id := len(project.Crates)
-	knownCrates[moduleName] = crateInfo{ID: id, Deps: deps}
-	project.Crates = append(project.Crates, crate)
+	id := len(singleton.project.Crates)
+	singleton.knownCrates[moduleName] = crateInfo{ID: id, Deps: deps}
+	singleton.project.Crates = append(singleton.project.Crates, crate)
 	// rust-analyzer requires that all crates belong to at least one root:
 	// https://github.com/rust-analyzer/rust-analyzer/issues/4735.
-	project.Roots = append(project.Roots, path.Dir(crate.RootModule))
+	singleton.project.Roots = append(singleton.project.Roots, path.Dir(crate.RootModule))
 	return id, crateName, true
 }
 
-func (r *projectGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
+func (singleton *projectGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
 	if !ctx.Config().IsEnvTrue(envVariableCollectRustDeps) {
 		return
 	}
 
-	project := rustProjectJson{}
-	knownCrates := make(map[string]crateInfo)
+	singleton.knownCrates = make(map[string]crateInfo)
 	ctx.VisitAllModules(func(module android.Module) {
-		appendLibraryAndDeps(ctx, &project, knownCrates, module)
+		singleton.appendLibraryAndDeps(ctx, module)
 	})
 
 	path := android.PathForOutput(ctx, rustProjectJsonFileName)
-	err := createJsonFile(project, path)
+	err := createJsonFile(singleton.project, path)
 	if err != nil {
 		ctx.Errorf(err.Error())
 	}
diff --git a/rust/project_json_test.go b/rust/project_json_test.go
index 8521940..8c1c436 100644
--- a/rust/project_json_test.go
+++ b/rust/project_json_test.go
@@ -18,6 +18,7 @@
 	"encoding/json"
 	"io/ioutil"
 	"path/filepath"
+	"strings"
 	"testing"
 
 	"android/soong/android"
@@ -100,22 +101,50 @@
 	rust_library {
 		name: "liba",
 		srcs: ["src/lib.rs"],
-		rlibs: ["libbindings"],
+		rlibs: ["libbindings1"],
 		crate_name: "a"
 	}
 	rust_bindgen {
-		name: "libbindings",
-		crate_name: "bindings",
-		source_stem: "bindings",
+		name: "libbindings1",
+		crate_name: "bindings1",
+		source_stem: "bindings1",
 		host_supported: true,
 		wrapper_src: "src/any.h",
 	}
+	rust_library_host {
+		name: "libb",
+		srcs: ["src/lib.rs"],
+		rustlibs: ["libbindings2"],
+		crate_name: "b"
+	}
+	rust_bindgen_host {
+		name: "libbindings2",
+		crate_name: "bindings2",
+		source_stem: "bindings2",
+		wrapper_src: "src/any.h",
+	}
 	` + GatherRequiredDepsForTest()
 	fs := map[string][]byte{
 		"src/lib.rs": nil,
 	}
 	jsonContent := testProjectJson(t, bp, fs)
-	validateJsonCrates(t, jsonContent)
+	crates := validateJsonCrates(t, jsonContent)
+	for _, c := range crates {
+		crate, ok := c.(map[string]interface{})
+		if !ok {
+			t.Fatalf("Unexpected type for crate: %v", c)
+		}
+		rootModule, ok := crate["root_module"].(string)
+		if !ok {
+			t.Fatalf("Unexpected type for root_module: %v", crate["root_module"])
+		}
+		if strings.Contains(rootModule, "libbindings1") && !strings.Contains(rootModule, "android_arm64") {
+			t.Errorf("The source for libbindings1 does not contain android_arm64, got %v", rootModule)
+		}
+		if strings.Contains(rootModule, "libbindings2") && !strings.Contains(rootModule, "linux_glibc") {
+			t.Errorf("The source for libbindings2 does not contain linux_glibc, got %v", rootModule)
+		}
+	}
 }
 
 func TestProjectJsonMultiVersion(t *testing.T) {
diff --git a/rust/testing.go b/rust/testing.go
index ee303ed..42b0da1 100644
--- a/rust/testing.go
+++ b/rust/testing.go
@@ -117,6 +117,7 @@
 	ctx.RegisterModuleType("rust_binary", RustBinaryFactory)
 	ctx.RegisterModuleType("rust_binary_host", RustBinaryHostFactory)
 	ctx.RegisterModuleType("rust_bindgen", RustBindgenFactory)
+	ctx.RegisterModuleType("rust_bindgen_host", RustBindgenHostFactory)
 	ctx.RegisterModuleType("rust_test", RustTestFactory)
 	ctx.RegisterModuleType("rust_test_host", RustTestHostFactory)
 	ctx.RegisterModuleType("rust_library", RustLibraryFactory)