Define Soong phony rules in Make

To support dist-for-goals in Soong, we need to define all phony rules
in Make so that dist-for-goals can insert additional dependencies on
them.  Collect all the phony rules in phonySingleton and write them
out as Make rules when Soong is embedded in Make, or as blueprint.Phony
rules when Soong is run standalone.

Test: m checkbuild
Change-Id: I68201eff30744b0f487fc4f11f033767b53a627d

android/makevars.go

@@ -17,12 +17,11 @@ package android
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
-	"os"
 	"strconv"
 	"strings"
 
 	"github.com/google/blueprint"
+	"github.com/google/blueprint/pathtools"
 	"github.com/google/blueprint/proptools"
 )
 
@@ -84,6 +83,11 @@ type MakeVarsContext interface {
 	// builder whenever a file matching the pattern as added or removed, without rerunning if a
 	// file that does not match the pattern is added to a searched directory.
 	GlobWithDeps(pattern string, excludes []string) ([]string, error)
+
+	// Phony creates a phony rule in Make, which will allow additional DistForGoal
+	// dependencies to be added to it.  Phony can be called on the same name multiple
+	// times to add additional dependencies.
+	Phony(names string, deps ...Path)
 }
 
 var _ PathContext = MakeVarsContext(nil)
@@ -130,9 +134,10 @@ var makeVarsProviders []makeVarsProvider
 
 type makeVarsContext struct {
 	SingletonContext
-	config Config
-	pctx   PackageContext
-	vars   []makeVarsVariable
+	config  Config
+	pctx    PackageContext
+	vars    []makeVarsVariable
+	phonies []phony
 }
 
 var _ MakeVarsContext = &makeVarsContext{}
@@ -144,6 +149,11 @@ type makeVarsVariable struct {
 	strict bool
 }
 
+type phony struct {
+	name string
+	deps []string
+}
+
 func (s *makeVarsSingleton) GenerateBuildActions(ctx SingletonContext) {
 	if !ctx.Config().EmbeddedInMake() {
 		return
@@ -152,11 +162,15 @@ func (s *makeVarsSingleton) GenerateBuildActions(ctx SingletonContext) {
 	outFile := absolutePath(PathForOutput(ctx,
 		"make_vars"+proptools.String(ctx.Config().productVariables.Make_suffix)+".mk").String())
 
+	lateOutFile := absolutePath(PathForOutput(ctx,
+		"late"+proptools.String(ctx.Config().productVariables.Make_suffix)+".mk").String())
+
 	if ctx.Failed() {
 		return
 	}
 
 	vars := []makeVarsVariable{}
+	var phonies []phony
 	for _, provider := range makeVarsProviders {
 		mctx := &makeVarsContext{
 			SingletonContext: ctx,
@@ -166,6 +180,7 @@ func (s *makeVarsSingleton) GenerateBuildActions(ctx SingletonContext) {
 		provider.call(mctx)
 
 		vars = append(vars, mctx.vars...)
+		phonies = append(phonies, mctx.phonies...)
 	}
 
 	if ctx.Failed() {
@@ -174,17 +189,16 @@ func (s *makeVarsSingleton) GenerateBuildActions(ctx SingletonContext) {
 
 	outBytes := s.writeVars(vars)
 
-	if _, err := os.Stat(absolutePath(outFile)); err == nil {
-		if data, err := ioutil.ReadFile(absolutePath(outFile)); err == nil {
-			if bytes.Equal(data, outBytes) {
-				return
-			}
-		}
-	}
-
-	if err := ioutil.WriteFile(absolutePath(outFile), outBytes, 0666); err != nil {
+	if err := pathtools.WriteFileIfChanged(outFile, outBytes, 0666); err != nil {
 		ctx.Errorf(err.Error())
 	}
+
+	lateOutBytes := s.writeLate(phonies)
+
+	if err := pathtools.WriteFileIfChanged(lateOutFile, lateOutBytes, 0666); err != nil {
+		ctx.Errorf(err.Error())
+	}
+
 }
 
 func (s *makeVarsSingleton) writeVars(vars []makeVarsVariable) []byte {
@@ -263,6 +277,26 @@ my_check_failed :=
 
 	fmt.Fprintln(buf, "\nsoong-compare-var :=")
 
+	fmt.Fprintln(buf)
+
+	return buf.Bytes()
+}
+
+func (s *makeVarsSingleton) writeLate(phonies []phony) []byte {
+	buf := &bytes.Buffer{}
+
+	fmt.Fprint(buf, `# Autogenerated file
+
+# Values written by Soong read after parsing all Android.mk files.
+
+
+`)
+
+	for _, phony := range phonies {
+		fmt.Fprintf(buf, ".PHONY: %s\n", phony.name)
+		fmt.Fprintf(buf, "%s: %s\n", phony.name, strings.Join(phony.deps, "\\\n  "))
+	}
+
 	return buf.Bytes()
 }
 
@@ -299,6 +333,10 @@ func (c *makeVarsContext) addVariable(name, ninjaStr string, strict, sort bool)
 	c.addVariableRaw(name, value, strict, sort)
 }
 
+func (c *makeVarsContext) addPhony(name string, deps []string) {
+	c.phonies = append(c.phonies, phony{name, deps})
+}
+
 func (c *makeVarsContext) Strict(name, ninjaStr string) {
 	c.addVariable(name, ninjaStr, true, false)
 }
@@ -318,3 +356,7 @@ func (c *makeVarsContext) CheckSorted(name, ninjaStr string) {
 func (c *makeVarsContext) CheckRaw(name, value string) {
 	c.addVariableRaw(name, value, false, false)
 }
+
+func (c *makeVarsContext) Phony(name string, deps ...Path) {
+	c.addPhony(name, Paths(deps).Strings())
+}