Revert "Remove desugar support"

This reverts commit 000280bb0e13902b2d19fd102ecf68d0dbbabfba.

Reason for revert: broke art veridex build

Change-Id: I9f7d7cdbe8e34671614687ac0b34c0338ef240e7
diff --git a/java/dex.go b/java/dex.go
index f729bad..642dee4 100644
--- a/java/dex.go
+++ b/java/dex.go
@@ -22,6 +22,78 @@
 	"android/soong/android"
 )
 
+var desugar = pctx.AndroidStaticRule("desugar",
+	blueprint.RuleParams{
+		Command: `rm -rf $dumpDir && mkdir -p $dumpDir && ` +
+			`${config.JavaCmd} ` +
+			`-Djdk.internal.lambda.dumpProxyClasses=$$(cd $dumpDir && pwd) ` +
+			`$javaFlags ` +
+			`-jar ${config.DesugarJar} $classpathFlags $desugarFlags ` +
+			`-i $in -o $out`,
+		CommandDeps: []string{"${config.DesugarJar}", "${config.JavaCmd}"},
+	},
+	"javaFlags", "classpathFlags", "desugarFlags", "dumpDir")
+
+func (j *Module) desugar(ctx android.ModuleContext, flags javaBuilderFlags,
+	classesJar android.Path, jarName string) android.Path {
+
+	desugarFlags := []string{
+		"--min_sdk_version " + j.minSdkVersionNumber(ctx),
+		"--desugar_try_with_resources_if_needed=false",
+		"--allow_empty_bootclasspath",
+	}
+
+	if inList("--core-library", j.deviceProperties.Dxflags) {
+		desugarFlags = append(desugarFlags, "--core_library")
+	}
+
+	desugarJar := android.PathForModuleOut(ctx, "desugar", jarName)
+	dumpDir := android.PathForModuleOut(ctx, "desugar", "classes")
+
+	javaFlags := ""
+	if ctx.Config().UseOpenJDK9() {
+		javaFlags = "--add-opens java.base/java.lang.invoke=ALL-UNNAMED"
+	}
+
+	var classpathFlags []string
+	classpathFlags = append(classpathFlags, flags.bootClasspath.FormDesugarClasspath("--bootclasspath_entry")...)
+	classpathFlags = append(classpathFlags, flags.classpath.FormDesugarClasspath("--classpath_entry")...)
+
+	var deps android.Paths
+	deps = append(deps, flags.bootClasspath...)
+	deps = append(deps, flags.classpath...)
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        desugar,
+		Description: "desugar",
+		Output:      desugarJar,
+		Input:       classesJar,
+		Implicits:   deps,
+		Args: map[string]string{
+			"dumpDir":        dumpDir.String(),
+			"javaFlags":      javaFlags,
+			"classpathFlags": strings.Join(classpathFlags, " "),
+			"desugarFlags":   strings.Join(desugarFlags, " "),
+		},
+	})
+
+	return desugarJar
+}
+
+var dx = pctx.AndroidStaticRule("dx",
+	blueprint.RuleParams{
+		Command: `rm -rf "$outDir" && mkdir -p "$outDir" && ` +
+			`${config.DxCmd} --dex --output=$outDir $dxFlags $in && ` +
+			`${config.SoongZipCmd} -o $outDir/classes.dex.jar -C $outDir -D $outDir && ` +
+			`${config.MergeZipsCmd} -D -stripFile "*.class" $out $outDir/classes.dex.jar $in`,
+		CommandDeps: []string{
+			"${config.DxCmd}",
+			"${config.SoongZipCmd}",
+			"${config.MergeZipsCmd}",
+		},
+	},
+	"outDir", "dxFlags")
+
 var d8 = pctx.AndroidStaticRule("d8",
 	blueprint.RuleParams{
 		Command: `rm -rf "$outDir" && mkdir -p "$outDir" && ` +
@@ -53,24 +125,39 @@
 	},
 	"outDir", "outDict", "dxFlags", "r8Flags")
 
-func (j *Module) dxFlags(ctx android.ModuleContext) []string {
+func (j *Module) dxFlags(ctx android.ModuleContext, fullD8 bool) []string {
 	flags := j.deviceProperties.Dxflags
-	// Translate all the DX flags to D8 ones until all the build files have been migrated
-	// to D8 flags. See: b/69377755
-	flags = android.RemoveListFromList(flags,
-		[]string{"--core-library", "--dex", "--multi-dex"})
+	if fullD8 {
+		// Translate all the DX flags to D8 ones until all the build files have been migrated
+		// to D8 flags. See: b/69377755
+		flags = android.RemoveListFromList(flags,
+			[]string{"--core-library", "--dex", "--multi-dex"})
+	}
 
 	if ctx.Config().Getenv("NO_OPTIMIZE_DX") != "" {
-		flags = append(flags, "--debug")
+		if fullD8 {
+			flags = append(flags, "--debug")
+		} else {
+			flags = append(flags, "--no-optimize")
+		}
 	}
 
 	if ctx.Config().Getenv("GENERATE_DEX_DEBUG") != "" {
 		flags = append(flags,
 			"--debug",
 			"--verbose")
+		if !fullD8 {
+			flags = append(flags,
+				"--dump-to="+android.PathForModuleOut(ctx, "classes.lst").String(),
+				"--dump-width=1000")
+		}
 	}
 
-	flags = append(flags, "--min-api "+j.minSdkVersionNumber(ctx))
+	if fullD8 {
+		flags = append(flags, "--min-api "+j.minSdkVersionNumber(ctx))
+	} else {
+		flags = append(flags, "--min-sdk-version="+j.minSdkVersionNumber(ctx))
+	}
 	return flags
 }
 
@@ -79,7 +166,7 @@
 
 	// When an app contains references to APIs that are not in the SDK specified by
 	// its LOCAL_SDK_VERSION for example added by support library or by runtime
-	// classes added by desugaring, we artifically raise the "SDK version" "linked" by
+	// classes added by desugar, we artifically raise the "SDK version" "linked" by
 	// ProGuard, to
 	// - suppress ProGuard warnings of referencing symbols unknown to the lower SDK version.
 	// - prevent ProGuard stripping subclass in the support library that extends class added in the higher SDK version.
@@ -136,8 +223,13 @@
 	classesJar android.Path, jarName string) android.Path {
 
 	useR8 := Bool(j.deviceProperties.Optimize.Enabled)
+	fullD8 := useR8 || ctx.Config().UseD8Desugar()
 
-	dxFlags := j.dxFlags(ctx)
+	if !fullD8 {
+		classesJar = j.desugar(ctx, flags, classesJar, jarName)
+	}
+
+	dxFlags := j.dxFlags(ctx, fullD8)
 
 	// Compile classes.jar into classes.dex and then javalib.jar
 	javalibJar := android.PathForModuleOut(ctx, "dex", jarName)
@@ -164,9 +256,15 @@
 			},
 		})
 	} else {
+		rule := dx
+		desc := "dx"
+		if fullD8 {
+			rule = d8
+			desc = "d8"
+		}
 		ctx.Build(pctx, android.BuildParams{
-			Rule:        d8,
-			Description: "d8",
+			Rule:        rule,
+			Description: desc,
 			Output:      javalibJar,
 			Input:       classesJar,
 			Args: map[string]string{