Allow dependencies from platform variants to APEX modules (reland).

When `test_for` dependencies are added from libraries to APEX modules,
they can be created from the platform variants of the libraries, since
those are used for building tests. Hence we need an alias from the
platform variant of the APEX module to have a target for those
dependencies.

This is only necessary for libraries that are split by the APEX
mutator, i.e. is a member of some APEX. Normally that's not the case
for test libraries, but there may be exceptions (read
com.android.art.testing).

This relands https://r.android.com/1654679 after decoupling it from the
topic that caused b/184239856.

Test: m nothing
Bug: 183882457
Change-Id: If643c75ce9bc25fa01ad9d1e3ba8e1d060d03bb2

apex/apex.go

@@ -1049,6 +1049,16 @@ func apexMutator(mctx android.BottomUpMutatorContext) {
 	if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
 		apexBundleName := mctx.ModuleName()
 		mctx.CreateVariations(apexBundleName)
+		if strings.HasPrefix(apexBundleName, "com.android.art") {
+			// Create an alias from the platform variant. This is done to make
+			// test_for dependencies work for modules that are split by the APEX
+			// mutator, since test_for dependencies always go to the platform variant.
+			// This doesn't happen for normal APEXes that are disjunct, so only do
+			// this for the overlapping ART APEXes.
+			// TODO(b/183882457): Remove this if the test_for functionality is
+			// refactored to depend on the proper APEX variants instead of platform.
+			mctx.CreateAliasVariation("", apexBundleName)
+		}
 	} else if o, ok := mctx.Module().(*OverrideApex); ok {
 		apexBundleName := o.GetOverriddenModuleName()
 		if apexBundleName == "" {
@@ -1056,6 +1066,10 @@ func apexMutator(mctx android.BottomUpMutatorContext) {
 			return
 		}
 		mctx.CreateVariations(apexBundleName)
+		if strings.HasPrefix(apexBundleName, "com.android.art") {
+			// TODO(b/183882457): See note for CreateAliasVariation above.
+			mctx.CreateAliasVariation("", apexBundleName)
+		}
 	}
 }
 

apex/apex_test.go

@@ -6947,6 +6947,56 @@ func TestIndirectTestFor(t *testing.T) {
 	ensureLinkedLibIs("myprivlib", "android_arm64_armv8-a_shared", "out/soong/.intermediates/mylib/", "android_arm64_armv8-a_shared/mylib.so")
 }
 
+func TestTestForForLibInOtherApex(t *testing.T) {
+	// This case is only allowed for known overlapping APEXes, i.e. the ART APEXes.
+	_ = testApex(t, `
+		apex {
+			name: "com.android.art",
+			key: "myapex.key",
+			native_shared_libs: ["mylib"],
+			updatable: false,
+		}
+
+		apex {
+			name: "com.android.art.debug",
+			key: "myapex.key",
+			native_shared_libs: ["mylib", "mytestlib"],
+			updatable: false,
+		}
+
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+
+		cc_library {
+			name: "mylib",
+			srcs: ["mylib.cpp"],
+			system_shared_libs: [],
+			stl: "none",
+			stubs: {
+				versions: ["1"],
+			},
+			apex_available: ["com.android.art", "com.android.art.debug"],
+		}
+
+		cc_library {
+			name: "mytestlib",
+			srcs: ["mylib.cpp"],
+			system_shared_libs: [],
+			shared_libs: ["mylib"],
+			stl: "none",
+			apex_available: ["com.android.art.debug"],
+			test_for: ["com.android.art"],
+		}
+	`,
+		android.MockFS{
+			"system/sepolicy/apex/com.android.art-file_contexts":       nil,
+			"system/sepolicy/apex/com.android.art.debug-file_contexts": nil,
+		}.AddToFixture())
+}
+
 // TODO(jungjw): Move this to proptools
 func intPtr(i int) *int {
 	return &i