java_sdk_library: Only expose impl jars when they are built

The implementation jars are not built if api_only: true. In that case
the jar paths must not be exposed implicitly as they will be nil and
they will just be ignored.

This change ensures that stubs are returned when the implementation
jars are not built.

Bug: 155164730
Test: m droid
Change-Id: Ic495982a5dcb2754916260e7d91d921a5da288ae

java/java_test.go

@@ -19,6 +19,7 @@ import (
 	"os"
 	"path/filepath"
 	"reflect"
+	"regexp"
 	"sort"
 	"strconv"
 	"strings"
@@ -1261,6 +1262,31 @@ func TestJavaSdkLibrary(t *testing.T) {
 	}
 }
 
+func TestJavaSdkLibrary_DoNotAccessImplWhenItIsNotBuilt(t *testing.T) {
+	ctx, _ := testJava(t, `
+		java_sdk_library {
+			name: "foo",
+			srcs: ["a.java"],
+			api_only: true,
+			public: {
+				enabled: true,
+			},
+		}
+
+		java_library {
+			name: "bar",
+			srcs: ["b.java"],
+			libs: ["foo"],
+		}
+		`)
+
+	// The bar library should depend on the stubs jar.
+	barLibrary := ctx.ModuleForTests("bar", "android_common").Rule("javac")
+	if expected, actual := `^-classpath .*:/[^:]*/turbine-combined/foo\.stubs\.jar$`, barLibrary.Args["classpath"]; !regexp.MustCompile(expected).MatchString(actual) {
+		t.Errorf("expected %q, found %#q", expected, actual)
+	}
+}
+
 func TestJavaSdkLibrary_UseSourcesFromAnotherSdkLibrary(t *testing.T) {
 	testJava(t, `
 		java_sdk_library {

java/sdk_library.go

@@ -1295,6 +1295,8 @@ func PrebuiltJars(ctx android.BaseModuleContext, baseName string, s sdkSpec) and
 
 func (module *SdkLibrary) sdkJars(ctx android.BaseModuleContext, sdkVersion sdkSpec, headerJars bool) android.Paths {
 
+	// Only provide access to the implementation library if it is actually built.
+	if module.requiresRuntimeImplementationLibrary() {
 		// Check any special cases for java_sdk_library.
 		//
 		// Only allow access to the implementation library in the following condition:
@@ -1306,6 +1308,7 @@ func (module *SdkLibrary) sdkJars(ctx android.BaseModuleContext, sdkVersion sdkS
 				return module.ImplementationJars()
 			}
 		}
+	}
 
 	return module.selectHeaderJarsForSdkVersion(ctx, sdkVersion)
 }