Merge "rust: rust_proc_macro host snapshot support."
diff --git a/rust/prebuilt.go b/rust/prebuilt.go
index 6f17272..6cdd07d 100644
--- a/rust/prebuilt.go
+++ b/rust/prebuilt.go
@@ -22,6 +22,7 @@
 	android.RegisterModuleType("rust_prebuilt_library", PrebuiltLibraryFactory)
 	android.RegisterModuleType("rust_prebuilt_dylib", PrebuiltDylibFactory)
 	android.RegisterModuleType("rust_prebuilt_rlib", PrebuiltRlibFactory)
+	android.RegisterModuleType("rust_prebuilt_proc_macro", PrebuiltProcMacroFactory)
 }
 
 type PrebuiltProperties struct {
@@ -38,8 +39,42 @@
 	Properties PrebuiltProperties
 }
 
+type prebuiltProcMacroDecorator struct {
+	android.Prebuilt
+
+	*procMacroDecorator
+	Properties PrebuiltProperties
+}
+
+func PrebuiltProcMacroFactory() android.Module {
+	module, _ := NewPrebuiltProcMacro(android.HostSupportedNoCross)
+	return module.Init()
+}
+
+type rustPrebuilt interface {
+	prebuiltSrcs() []string
+	prebuilt() *android.Prebuilt
+}
+
+func NewPrebuiltProcMacro(hod android.HostOrDeviceSupported) (*Module, *prebuiltProcMacroDecorator) {
+	module, library := NewProcMacro(hod)
+	prebuilt := &prebuiltProcMacroDecorator{
+		procMacroDecorator: library,
+	}
+	module.compiler = prebuilt
+
+	addSrcSupplier(module, prebuilt)
+
+	return module, prebuilt
+}
+
 var _ compiler = (*prebuiltLibraryDecorator)(nil)
 var _ exportedFlagsProducer = (*prebuiltLibraryDecorator)(nil)
+var _ rustPrebuilt = (*prebuiltLibraryDecorator)(nil)
+
+var _ compiler = (*prebuiltProcMacroDecorator)(nil)
+var _ exportedFlagsProducer = (*prebuiltProcMacroDecorator)(nil)
+var _ rustPrebuilt = (*prebuiltProcMacroDecorator)(nil)
 
 func PrebuiltLibraryFactory() android.Module {
 	module, _ := NewPrebuiltLibrary(android.HostAndDeviceSupported)
@@ -56,7 +91,7 @@
 	return module.Init()
 }
 
-func addSrcSupplier(module android.PrebuiltInterface, prebuilt *prebuiltLibraryDecorator) {
+func addSrcSupplier(module android.PrebuiltInterface, prebuilt rustPrebuilt) {
 	srcsSupplier := func(_ android.BaseModuleContext, _ android.Module) []string {
 		return prebuilt.prebuiltSrcs()
 	}
@@ -152,3 +187,44 @@
 func (prebuilt *prebuiltLibraryDecorator) prebuilt() *android.Prebuilt {
 	return &prebuilt.Prebuilt
 }
+
+func (prebuilt *prebuiltProcMacroDecorator) prebuiltSrcs() []string {
+	srcs := prebuilt.Properties.Srcs
+	return srcs
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) prebuilt() *android.Prebuilt {
+	return &prebuilt.Prebuilt
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) compilerProps() []interface{} {
+	return append(prebuilt.procMacroDecorator.compilerProps(),
+		&prebuilt.Properties)
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) android.Path {
+	prebuilt.flagExporter.exportLinkDirs(android.PathsForModuleSrc(ctx, prebuilt.Properties.Link_dirs).Strings()...)
+	prebuilt.flagExporter.setProvider(ctx)
+
+	srcPath, paths := srcPathFromModuleSrcs(ctx, prebuilt.prebuiltSrcs())
+	if len(paths) > 0 {
+		ctx.PropertyErrorf("srcs", "prebuilt libraries can only have one entry in srcs (the prebuilt path)")
+	}
+	prebuilt.baseCompiler.unstrippedOutputFile = srcPath
+	return srcPath
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) rustdoc(ctx ModuleContext, flags Flags,
+	deps PathDeps) android.OptionalPath {
+
+	return android.OptionalPath{}
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) compilerDeps(ctx DepsContext, deps Deps) Deps {
+	deps = prebuilt.baseCompiler.compilerDeps(ctx, deps)
+	return deps
+}
+
+func (prebuilt *prebuiltProcMacroDecorator) nativeCoverage() bool {
+	return false
+}
diff --git a/rust/proc_macro.go b/rust/proc_macro.go
index 974c096..f8a4bbd 100644
--- a/rust/proc_macro.go
+++ b/rust/proc_macro.go
@@ -33,6 +33,7 @@
 }
 
 type procMacroInterface interface {
+	ProcMacro() bool
 }
 
 var _ compiler = (*procMacroDecorator)(nil)
@@ -90,6 +91,10 @@
 	return rlibAutoDep
 }
 
+func (procMacro *procMacroDecorator) ProcMacro() bool {
+	return true
+}
+
 func (procMacro *procMacroDecorator) everInstallable() bool {
 	// Proc_macros are never installed
 	return false
diff --git a/rust/rust.go b/rust/rust.go
index 1c718a4..d627261 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -27,6 +27,7 @@
 	cc_config "android/soong/cc/config"
 	"android/soong/fuzz"
 	"android/soong/rust/config"
+	"android/soong/snapshot"
 )
 
 var pctx = android.NewPackageContext("android/soong/rust")
@@ -806,6 +807,13 @@
 	return mod.Properties.Installable
 }
 
+func (mod *Module) ProcMacro() bool {
+	if pm, ok := mod.compiler.(procMacroInterface); ok {
+		return pm.ProcMacro()
+	}
+	return false
+}
+
 func (mod *Module) toolchain(ctx android.BaseModuleContext) config.Toolchain {
 	if mod.cachedToolchain == nil {
 		mod.cachedToolchain = config.FindToolchain(ctx.Os(), ctx.Arch())
@@ -920,12 +928,13 @@
 		}
 
 		apexInfo := actx.Provider(android.ApexInfoProvider).(android.ApexInfo)
-		if !proptools.BoolDefault(mod.Installable(), mod.EverInstallable()) {
+		if !proptools.BoolDefault(mod.Installable(), mod.EverInstallable()) && !mod.ProcMacro() {
 			// If the module has been specifically configure to not be installed then
 			// hide from make as otherwise it will break when running inside make as the
 			// output path to install will not be specified. Not all uninstallable
 			// modules can be hidden from make as some are needed for resolving make
-			// side dependencies.
+			// side dependencies. In particular, proc-macros need to be captured in the
+			// host snapshot.
 			mod.HideFromMake()
 		} else if !mod.installable(apexInfo) {
 			mod.SkipInstall()
@@ -1046,7 +1055,7 @@
 }
 
 func (mod *Module) Prebuilt() *android.Prebuilt {
-	if p, ok := mod.compiler.(*prebuiltLibraryDecorator); ok {
+	if p, ok := mod.compiler.(rustPrebuilt); ok {
 		return p.prebuilt()
 	}
 	return nil
@@ -1501,6 +1510,7 @@
 }
 
 var _ android.HostToolProvider = (*Module)(nil)
+var _ snapshot.RelativeInstallPath = (*Module)(nil)
 
 func (mod *Module) HostToolPath() android.OptionalPath {
 	if !mod.Host() {
@@ -1508,6 +1518,10 @@
 	}
 	if binary, ok := mod.compiler.(*binaryDecorator); ok {
 		return android.OptionalPathForPath(binary.baseCompiler.path)
+	} else if pm, ok := mod.compiler.(*procMacroDecorator); ok {
+		// Even though proc-macros aren't strictly "tools", since they target the compiler
+		// and act as compiler plugins, we treat them similarly.
+		return android.OptionalPathForPath(pm.baseCompiler.path)
 	}
 	return android.OptionalPath{}
 }
diff --git a/snapshot/host_fake_snapshot.go b/snapshot/host_fake_snapshot.go
index 6b4e12b..1a75f3a 100644
--- a/snapshot/host_fake_snapshot.go
+++ b/snapshot/host_fake_snapshot.go
@@ -114,13 +114,13 @@
 		if !apexInfo.IsForPlatform() {
 			return
 		}
-		path := hostBinToolPath(module)
+		path := hostToolPath(module)
 		if path.Valid() && path.String() != "" {
 			outFile := filepath.Join(c.snapshotDir, path.String())
 			if !seen[outFile] {
 				seen[outFile] = true
 				outputs = append(outputs, WriteStringToFileRule(ctx, "", outFile))
-				jsonData = append(jsonData, *hostBinJsonDesc(module))
+				jsonData = append(jsonData, *hostJsonDesc(module))
 			}
 		}
 	})
diff --git a/snapshot/host_snapshot.go b/snapshot/host_snapshot.go
index 09a382e..75b5e88 100644
--- a/snapshot/host_snapshot.go
+++ b/snapshot/host_snapshot.go
@@ -19,6 +19,7 @@
 	"fmt"
 	"path/filepath"
 	"sort"
+	"strings"
 
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
@@ -62,6 +63,11 @@
 	installDir android.InstallPath
 }
 
+type ProcMacro interface {
+	ProcMacro() bool
+	CrateName() string
+}
+
 func hostSnapshotFactory() android.Module {
 	module := &hostSnapshot{}
 	initHostToolsModule(module)
@@ -94,7 +100,7 @@
 
 	// Create JSON file based on the direct dependencies
 	ctx.VisitDirectDeps(func(dep android.Module) {
-		desc := hostBinJsonDesc(dep)
+		desc := hostJsonDesc(dep)
 		if desc != nil {
 			jsonData = append(jsonData, *desc)
 		}
@@ -183,7 +189,7 @@
 }
 
 // Get host tools path and relative install string helpers
-func hostBinToolPath(m android.Module) android.OptionalPath {
+func hostToolPath(m android.Module) android.OptionalPath {
 	if provider, ok := m.(android.HostToolProvider); ok {
 		return provider.HostToolPath()
 	}
@@ -198,18 +204,30 @@
 	return outString
 }
 
-// Create JSON description for given module, only create descriptions for binary modueles which
-// provide a valid HostToolPath
-func hostBinJsonDesc(m android.Module) *SnapshotJsonFlags {
-	path := hostBinToolPath(m)
+// Create JSON description for given module, only create descriptions for binary modules
+// and rust_proc_macro modules which provide a valid HostToolPath
+func hostJsonDesc(m android.Module) *SnapshotJsonFlags {
+	path := hostToolPath(m)
 	relPath := hostRelativePathString(m)
+	procMacro := false
+	moduleStem := filepath.Base(path.String())
+	crateName := ""
+
+	if pm, ok := m.(ProcMacro); ok && pm.ProcMacro() {
+		procMacro = pm.ProcMacro()
+		moduleStem = strings.TrimSuffix(moduleStem, filepath.Ext(moduleStem))
+		crateName = pm.CrateName()
+	}
+
 	if path.Valid() && path.String() != "" {
 		return &SnapshotJsonFlags{
 			ModuleName:          m.Name(),
-			ModuleStemName:      filepath.Base(path.String()),
+			ModuleStemName:      moduleStem,
 			Filename:            path.String(),
 			Required:            append(m.HostRequiredModuleNames(), m.RequiredModuleNames()...),
 			RelativeInstallPath: relPath,
+			RustProcMacro:       procMacro,
+			CrateName:           crateName,
 		}
 	}
 	return nil
diff --git a/snapshot/snapshot_base.go b/snapshot/snapshot_base.go
index 79d3cf6..4a14f2e 100644
--- a/snapshot/snapshot_base.go
+++ b/snapshot/snapshot_base.go
@@ -114,6 +114,8 @@
 	RelativeInstallPath string `json:",omitempty"`
 	Filename            string `json:",omitempty"`
 	ModuleStemName      string `json:",omitempty"`
+	RustProcMacro       bool   `json:",omitempty"`
+	CrateName           string `json:",omitempty"`
 
 	// dependencies
 	Required []string `json:",omitempty"`