Fix non-determinism in prebuilt selection

This relands aosp/2978137 with acknowledgement of soong namespaces.

If multiple versions of the prebuilt module sdk share the same soong
config namespace, then PrebuiltPostDepsMutator rewrites rdeps to one of
those prebuilts in a non-deterministic way.

This CL uses apex_contributions to make this deterministic. Multiple
prebuilts will not be allowed to have their prefer evaluate to true. If
this happens, one of the prebuilts must be explicitly declared in
apex_contributions.

This CL also fixes the special-casing of the top-level
java_sdk_library_import in ReplaceDirectDependencies. For
framework-foo.v2, it will use BaseModuleName framework-foo instead of
SdkLibraryName framework-foo.v2 to determine if the source module has
been selected.

Test: ran the previously failing cmd of b/327552112
Test: Added a unit test
Test: aninja -t query
    out/soong/.intermediates/packages/modules/Permission/SafetyCenter/Config/safety-center-config/android_common/javac/safety-center-config.jar
    | grep module_sdk is empty (should not cause a regression for
    323454855)
Change-Id: Id484a41192085c50b7e34ad415c6e195edb0d006

android/prebuilt.go

@@ -534,6 +534,35 @@ func hideUnflaggedModules(ctx BottomUpMutatorContext, psi PrebuiltSelectionInfoM
 		for _, moduleInFamily := range allModulesInFamily {
 			if moduleInFamily.Name() != selectedModuleInFamily.Name() {
 				moduleInFamily.HideFromMake()
+				// If this is a prebuilt module, unset properties.UsePrebuilt
+				// properties.UsePrebuilt might evaluate to true via soong config var fallback mechanism
+				// Set it to false explicitly so that the following mutator does not replace rdeps to this unselected prebuilt
+				if p := GetEmbeddedPrebuilt(moduleInFamily); p != nil {
+					p.properties.UsePrebuilt = false
+				}
+			}
+		}
+	}
+	// Do a validation pass to make sure that multiple prebuilts of a specific module are not selected.
+	// This might happen if the prebuilts share the same soong config var namespace.
+	// This should be an error, unless one of the prebuilts has been explicitly declared in apex_contributions
+	var selectedPrebuilt Module
+	for _, moduleInFamily := range allModulesInFamily {
+		// Skip if this module is in a different namespace
+		if !moduleInFamily.ExportedToMake() {
+			continue
+		}
+		// Skip for the top-level java_sdk_library_(_import). This has some special cases that need to be addressed first.
+		// This does not run into non-determinism because PrebuiltPostDepsMutator also has the special case
+		if sdkLibrary, ok := moduleInFamily.(interface{ SdkLibraryName() *string }); ok && sdkLibrary.SdkLibraryName() != nil {
+			continue
+		}
+		if p := GetEmbeddedPrebuilt(moduleInFamily); p != nil && p.properties.UsePrebuilt {
+			if selectedPrebuilt == nil {
+				selectedPrebuilt = moduleInFamily
+			} else {
+				ctx.ModuleErrorf("Multiple prebuilt modules %v and %v have been marked as preferred for this source module. "+
+					"Please add the appropriate prebuilt module to apex_contributions for this release config.", selectedPrebuilt.Name(), moduleInFamily.Name())
 			}
 		}
 	}
@@ -562,7 +591,7 @@ func PrebuiltPostDepsMutator(ctx BottomUpMutatorContext) {
 						// If we do not special-case this here, rdeps referring to a java_sdk_library in next builds via libs
 						// will get prebuilt stubs
 						// TODO (b/308187268): Remove this after the apexes have been added to apex_contributions
-						if psi.IsSelected(*sdkLibrary.SdkLibraryName()) {
+						if psi.IsSelected(name) {
 							return false
 						}
 					}

apex/apex_test.go

@@ -6199,7 +6199,7 @@ func TestBootDexJarsFromSourcesAndPrebuilts(t *testing.T) {
 		`)
 	})
 
-	t.Run("Co-existing unflagged apexes should create a duplicate deapexer error in hiddenapi processing", func(t *testing.T) {
+	t.Run("Co-existing unflagged apexes should create a duplicate module error", func(t *testing.T) {
 		bp := `
 		// Source
 		apex {
@@ -6273,7 +6273,7 @@ func TestBootDexJarsFromSourcesAndPrebuilts(t *testing.T) {
 		}
 	`
 
-		testDexpreoptWithApexes(t, bp, "Multiple installable prebuilt APEXes provide ambiguous deapexers: prebuilt_myapex.v1 and prebuilt_myapex.v2", preparer, fragment)
+		testDexpreoptWithApexes(t, bp, "Multiple prebuilt modules prebuilt_myapex.v1 and prebuilt_myapex.v2 have been marked as preferred for this source module", preparer, fragment)
 	})
 
 }

cc/prebuilt_test.go

@@ -610,3 +610,95 @@ func TestMultiplePrebuilts(t *testing.T) {
 		android.AssertStringEquals(t, "unexpected LOCAL_MODULE", "libbar", entries.EntryMap["LOCAL_MODULE"][0])
 	}
 }
+
+// Setting prefer on multiple prebuilts is an error, unless one of them is also listed in apex_contributions
+func TestMultiplePrebuiltsPreferredUsingLegacyFlags(t *testing.T) {
+	bp := `
+		// an rdep
+		cc_library {
+			name: "libfoo",
+			shared_libs: ["libbar"],
+		}
+
+		// multiple variations of dep
+		// source
+		cc_library {
+			name: "libbar",
+		}
+		// prebuilt "v1"
+		cc_prebuilt_library_shared {
+			name: "libbar",
+			srcs: ["libbar.so"],
+			prefer: true,
+		}
+		// prebuilt "v2"
+		cc_prebuilt_library_shared {
+			name: "libbar.v2",
+			stem: "libbar",
+			source_module_name: "libbar",
+			srcs: ["libbar.so"],
+			prefer: true,
+		}
+
+		// selectors
+		apex_contributions {
+			name: "myapex_contributions",
+			contents: [%v],
+		}
+		all_apex_contributions {name: "all_apex_contributions"}
+	`
+	hasDep := func(ctx *android.TestContext, m android.Module, wantDep android.Module) bool {
+		t.Helper()
+		var found bool
+		ctx.VisitDirectDeps(m, func(dep blueprint.Module) {
+			if dep == wantDep {
+				found = true
+			}
+		})
+		return found
+	}
+
+	testCases := []struct {
+		desc                   string
+		selectedDependencyName string
+		expectedDependencyName string
+		expectedErr            string
+	}{
+		{
+			desc:        "Multiple prebuilts have prefer: true",
+			expectedErr: "Multiple prebuilt modules prebuilt_libbar and prebuilt_libbar.v2 have been marked as preferred for this source module",
+		},
+		{
+			desc:                   "Multiple prebuilts have prefer: true. The prebuilt listed in apex_contributions wins.",
+			selectedDependencyName: `"prebuilt_libbar"`,
+			expectedDependencyName: "prebuilt_libbar",
+		},
+	}
+
+	for _, tc := range testCases {
+		preparer := android.GroupFixturePreparers(
+			android.FixtureRegisterWithContext(func(ctx android.RegistrationContext) {
+				android.RegisterApexContributionsBuildComponents(ctx)
+			}),
+			android.FixtureModifyProductVariables(func(variables android.FixtureProductVariables) {
+				variables.BuildFlags = map[string]string{
+					"RELEASE_APEX_CONTRIBUTIONS_ADSERVICES": "myapex_contributions",
+				}
+			}),
+		)
+		if tc.expectedErr != "" {
+			preparer = preparer.ExtendWithErrorHandler(android.FixtureExpectsAtLeastOneErrorMatchingPattern(tc.expectedErr))
+		}
+
+		ctx := testPrebuilt(t, fmt.Sprintf(bp, tc.selectedDependencyName), map[string][]byte{
+			"libbar.so": nil,
+			"crtx.o":    nil,
+		}, preparer)
+		if tc.expectedErr != "" {
+			return // the fixture will assert that the excepted err has been raised
+		}
+		libfoo := ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_shared").Module()
+		expectedDependency := ctx.ModuleForTests(tc.expectedDependencyName, "android_arm64_armv8-a_shared").Module()
+		android.AssertBoolEquals(t, fmt.Sprintf("expected dependency from %s to %s\n", libfoo.Name(), tc.expectedDependencyName), true, hasDep(ctx, libfoo, expectedDependency))
+	}
+}