Create config_setting per apex_name

These are created by bp2build in /build/bazel/rules/apex. Eventually
these config_settings should likely be colocated with the source apex
definition.

Another alternative was to make Bazel's apex a macro that generates a
config_setting. I did not pursue this further for now since it requires the
apex_available of every allowlisted cc_library to also be allowlisted.
This might not always be true (e.g. com.android.runtime)

Test: go test ./bp2build
Change-Id: Ibbb14b0d9c1491b3c79b7634a18d9d35b03922c1

bazel/configurability.go

@@ -268,9 +268,8 @@ func (ct configurationType) validateConfig(config string) {
 	case productVariables:
 		// do nothing
 	case osAndInApex:
-		if _, ok := osAndInApexMap[config]; !ok {
-			panic(fmt.Errorf("Unknown os+in_apex config: %s", config))
-		}
+		// do nothing
+		// this axis can contain additional per-apex keys
 	case inApex:
 		if _, ok := inApexMap[config]; !ok {
 			panic(fmt.Errorf("Unknown in_apex config: %s", config))
@@ -299,7 +298,10 @@ func (ca ConfigurationAxis) SelectKey(config string) string {
 		}
 		return fmt.Sprintf("%s:%s", productVariableBazelPackage, config)
 	case osAndInApex:
-		return osAndInApexMap[config]
+		if ret, exists := osAndInApexMap[config]; exists {
+			return ret
+		}
+		return config
 	case inApex:
 		return inApexMap[config]
 	default:

bp2build/cc_library_conversion_test.go

@@ -4454,3 +4454,32 @@ cc_library {
 		},
 	})
 }
+
+// Test that a config_setting specific to an apex is created by cc_library.
+func TestCcLibraryCreatesInApexConfigSetting(t *testing.T) {
+	runCcLibraryTestCase(t, Bp2buildTestCase{
+		Description:                "cc_library creates a config_setting for each apex in apex_available",
+		ModuleTypeUnderTest:        "cc_library",
+		ModuleTypeUnderTestFactory: cc.LibraryFactory,
+		Dir:                        "build/bazel/rules/apex",
+		Blueprint: `
+cc_library {
+	name: "foo",
+	apex_available: [
+	"//apex_available:platform", // This will be skipped, since it is equivalent to //build/bazel/rules/apex:android-non_apex
+	"myapex"
+	],
+}`,
+		ExpectedBazelTargets: []string{
+			MakeBazelTargetNoRestrictions(
+				"config_setting",
+				"android-in_myapex",
+				AttrNameToString{
+					"flag_values": `{
+        "//build/bazel/rules/apex:apex_name": "myapex",
+    }`,
+				},
+			),
+		},
+	})
+}

cc/bp2build.go

@@ -17,6 +17,7 @@ import (
 	"fmt"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"android/soong/android"
 	"android/soong/bazel"
@@ -1196,6 +1197,63 @@ func availableToSameApexes(a, b []string) bool {
 	return !differ
 }
 
+var (
+	apexConfigSettingKey  = android.NewOnceKey("apexConfigSetting")
+	apexConfigSettingLock sync.Mutex
+)
+
+func getApexConfigSettingMap(config android.Config) *map[string]bool {
+	return config.Once(apexConfigSettingKey, func() interface{} {
+		return &map[string]bool{}
+	}).(*map[string]bool)
+}
+
+// Create a config setting for this apex in build/bazel/rules/apex
+// The use case for this is stub/impl selection in cc libraries
+// Long term, these config_setting(s) should be colocated with the respective apex definitions.
+// Note that this is an anti-pattern: The config_setting should be created from the apex definition
+// and not from a cc_library.
+// This anti-pattern is needed today since not all apexes have been allowlisted.
+func createInApexConfigSetting(ctx android.TopDownMutatorContext, apexName string) {
+	if apexName == android.AvailableToPlatform || apexName == android.AvailableToAnyApex {
+		// These correspond to android-non_apex and android-in_apex
+		return
+	}
+	apexConfigSettingLock.Lock()
+	defer apexConfigSettingLock.Unlock()
+
+	// Return if a config_setting has already been created
+	acsm := getApexConfigSettingMap(ctx.Config())
+	if _, exists := (*acsm)[apexName]; exists {
+		return
+	}
+	(*acsm)[apexName] = true
+
+	csa := bazel.ConfigSettingAttributes{
+		Flag_values: bazel.StringMapAttribute{
+			"//build/bazel/rules/apex:apex_name": apexName,
+		},
+	}
+	ca := android.CommonAttributes{
+		Name: "android-in_" + apexName,
+	}
+	ctx.CreateBazelConfigSetting(
+		csa,
+		ca,
+		"build/bazel/rules/apex",
+	)
+}
+
+func inApexConfigSetting(apexAvailable string) string {
+	if apexAvailable == android.AvailableToPlatform {
+		return bazel.AndroidAndNonApex
+	}
+	if apexAvailable == android.AvailableToAnyApex {
+		return bazel.AndroidAndInApex
+	}
+	return "//build/bazel/rules/apex:android-in_" + apexAvailable
+}
+
 func setStubsForDynamicDeps(ctx android.BazelConversionPathContext, axis bazel.ConfigurationAxis,
 	config string, apexAvailable []string, dynamicLibs bazel.LabelList, dynamicDeps *bazel.LabelListAttribute, ind int, buildNonApexWithStubs bool) {
 
@@ -1241,6 +1299,13 @@ func setStubsForDynamicDeps(ctx android.BazelConversionPathContext, axis bazel.C
 			dynamicDeps.SetSelectValue(bazel.OsAndInApexAxis, bazel.AndroidAndNonApex, bazel.FirstUniqueBazelLabelList(nonApexSelectValue))
 		}
 	}
+
+	// Create a config_setting for each apex_available.
+	// This will be used to select impl of a dep if dep is available to the same apex.
+	for _, aa := range apexAvailable {
+		createInApexConfigSetting(ctx.(android.TopDownMutatorContext), aa)
+	}
+
 }
 
 func (la *linkerAttributes) convertStripProps(ctx android.BazelConversionPathContext, module *Module) {