Add the implicit deps of javacRE

This includes
1. the prebuilt javac binary
2. the input .java files
3. the jars that are placed on the classpath during javac

(2) is passed via ${out}.rsp. This rsp file gets populated with the
input java files

For (3), this CL creates a new intermediate file whose content is
comma separated jars available on the classpath (this is the format
expected by rewrapper). This file is then registered in RSPFiles of
javacRE command, so that it gets passed to the rewrapper cmd as
`--input_list_paths`

(rspfiles are necesary for modules like framework-minus-apex to avoid
exceeding cmd line limits)

Bug: 308687455
Test: m framework-minus-apex; # verified that the relevant files are
added as `--inputs` of javac

Change-Id: I2ab9277fc394eb00454ef503c78a9f3451e596ac

java/builder.go

@@ -19,6 +19,7 @@ package java
 // functions.
 
 import (
+	"fmt"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -68,6 +69,8 @@ var (
 		}, map[string]*remoteexec.REParams{
 			"$javaTemplate": &remoteexec.REParams{
 				Labels:       map[string]string{"type": "compile", "lang": "java", "compiler": "javac"},
+				Inputs:       []string{"${config.JavacCmd}"},
+				RSPFiles:     []string{"${out}.rsp", "${javacREClasspathDeps}"},
 				ExecStrategy: "${config.REJavacExecStrategy}",
 				Platform:     map[string]string{remoteexec.PoolKey: "${config.REJavaPool}"},
 			},
@@ -86,7 +89,7 @@ var (
 				Platform:     map[string]string{remoteexec.PoolKey: "${config.REJavaPool}"},
 			},
 		}, []string{"javacFlags", "bootClasspath", "classpath", "processorpath", "processor", "srcJars", "srcJarDir",
-			"outDir", "annoDir", "annoSrcJar", "javaVersion"}, nil)
+			"outDir", "annoDir", "annoSrcJar", "javaVersion"}, []string{"javacREClasspathDeps"})
 
 	_ = pctx.VariableFunc("kytheCorpus",
 		func(ctx android.PackageVarContext) string { return ctx.Config().XrefCorpusName() })
@@ -601,8 +604,35 @@ func transformJavaToClasses(ctx android.ModuleContext, outputFile android.Writab
 		annoDir = filepath.Join(shardDir, annoDir)
 	}
 	rule := javac
+	args := map[string]string{
+		"javacFlags":    flags.javacFlags,
+		"bootClasspath": bootClasspath,
+		"classpath":     classpathArg,
+		"processorpath": flags.processorPath.FormJavaClassPath("-processorpath"),
+		"processor":     processor,
+		"srcJars":       strings.Join(srcJars.Strings(), " "),
+		"srcJarDir":     android.PathForModuleOut(ctx, intermediatesDir, srcJarDir).String(),
+		"outDir":        android.PathForModuleOut(ctx, intermediatesDir, outDir).String(),
+		"annoDir":       android.PathForModuleOut(ctx, intermediatesDir, annoDir).String(),
+		"annoSrcJar":    annoSrcJar.String(),
+		"javaVersion":   flags.javaVersion.String(),
+	}
+
 	if ctx.Config().UseRBE() && ctx.Config().IsEnvTrue("RBE_JAVAC") {
 		rule = javacRE
+
+		// Write the classpath deps to a file that can be passed as an input to javacRE.
+		// Skip the shardIdx if the java library is unsharded
+		shardIdxSuffix := strconv.Itoa(shardIdx)
+		if shardIdx == -1 {
+			shardIdxSuffix = ""
+		}
+		javacREClasspathDepsFile := outputFile.ReplaceExtension(ctx, fmt.Sprintf("javacre.classpathdeps%v", shardIdxSuffix))
+		android.WriteFileRule(ctx, javacREClasspathDepsFile, strings.Join(javacClasspath.Strings(), ",")) // The classpath jars are an implicit dep of javacRE
+		args["javacREClasspathDeps"] = javacREClasspathDepsFile.String()
+
+		// Add the deps file to the implicit inputs
+		deps = append(deps, javacREClasspathDepsFile)
 	}
 	ctx.Build(pctx, android.BuildParams{
 		Rule:           rule,
@@ -611,19 +641,7 @@ func transformJavaToClasses(ctx android.ModuleContext, outputFile android.Writab
 		ImplicitOutput: annoSrcJar,
 		Inputs:         srcFiles,
 		Implicits:      deps,
-		Args: map[string]string{
-			"javacFlags":    flags.javacFlags,
-			"bootClasspath": bootClasspath,
-			"classpath":     classpathArg,
-			"processorpath": flags.processorPath.FormJavaClassPath("-processorpath"),
-			"processor":     processor,
-			"srcJars":       strings.Join(srcJars.Strings(), " "),
-			"srcJarDir":     android.PathForModuleOut(ctx, intermediatesDir, srcJarDir).String(),
-			"outDir":        android.PathForModuleOut(ctx, intermediatesDir, outDir).String(),
-			"annoDir":       android.PathForModuleOut(ctx, intermediatesDir, annoDir).String(),
-			"annoSrcJar":    annoSrcJar.String(),
-			"javaVersion":   flags.javaVersion.String(),
-		},
+		Args:           args,
 	})
 }