Add __ANDROID_SDK_VERSION__=<ver> macro

sdk_version is passed for relevant variants.
If not specified or "current",
it maps to "10000" for platform variants, and
"min_sdk_version" of the apex for apex variants.

Bug: 150860940
Test: m (soong test)
      manually check build.ninja
Change-Id: I5102ab0c5086b5ad29d16ac45af55d32062167b4
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 2b13197..a2dcfaf 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -1687,6 +1687,7 @@
 			name: "otherapex",
 			key: "myapex.key",
 			native_shared_libs: ["mylib", "mylib2"],
+			min_sdk_version: "29",
 		}
 
 		apex_key {
@@ -1721,15 +1722,18 @@
 	// non-APEX variant does not have __ANDROID_APEX__ defined
 	mylibCFlags := ctx.ModuleForTests("mylib", "android_arm64_armv8-a_static").Rule("cc").Args["cFlags"]
 	ensureNotContains(t, mylibCFlags, "-D__ANDROID_APEX__")
+	ensureContains(t, mylibCFlags, "-D__ANDROID_SDK_VERSION__=10000")
 
-	// APEX variant has __ANDROID_APEX__ defined
+	// APEX variant has __ANDROID_APEX__ and __ANDROID_APEX_SDK__ defined
 	mylibCFlags = ctx.ModuleForTests("mylib", "android_arm64_armv8-a_static_myapex").Rule("cc").Args["cFlags"]
 	ensureContains(t, mylibCFlags, "-D__ANDROID_APEX__")
+	ensureContains(t, mylibCFlags, "-D__ANDROID_SDK_VERSION__=10000")
 	ensureNotContains(t, mylibCFlags, "-D__ANDROID_APEX_MYAPEX__")
 
-	// APEX variant has __ANDROID_APEX__ defined
+	// APEX variant has __ANDROID_APEX__ and __ANDROID_APEX_SDK__ defined
 	mylibCFlags = ctx.ModuleForTests("mylib", "android_arm64_armv8-a_static_otherapex").Rule("cc").Args["cFlags"]
 	ensureContains(t, mylibCFlags, "-D__ANDROID_APEX__")
+	ensureContains(t, mylibCFlags, "-D__ANDROID_SDK_VERSION__=29")
 	ensureNotContains(t, mylibCFlags, "-D__ANDROID_APEX_OTHERAPEX__")
 
 	// When cc_library sets use_apex_name_macro: true
diff --git a/cc/cc.go b/cc/cc.go
index 8b3c772..04d30f1 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -290,6 +290,7 @@
 	staticBinary() bool
 	header() bool
 	toolchain() config.Toolchain
+	canUseSdk() bool
 	useSdk() bool
 	sdkVersion() string
 	useVndk() bool
@@ -313,6 +314,7 @@
 	useClangLld(actx ModuleContext) bool
 	isForPlatform() bool
 	apexName() string
+	apexSdkVersion() int
 	hasStubsVariants() bool
 	isStubs() bool
 	bootstrap() bool
@@ -1045,8 +1047,12 @@
 	return ctx.mod.header()
 }
 
+func (ctx *moduleContextImpl) canUseSdk() bool {
+	return ctx.ctx.Device() && !ctx.useVndk() && !ctx.inRamdisk() && !ctx.inRecovery() && !ctx.ctx.Fuchsia()
+}
+
 func (ctx *moduleContextImpl) useSdk() bool {
-	if ctx.ctx.Device() && !ctx.useVndk() && !ctx.inRamdisk() && !ctx.inRecovery() && !ctx.ctx.Fuchsia() {
+	if ctx.canUseSdk() {
 		return String(ctx.mod.Properties.Sdk_version) != ""
 	}
 	return false
@@ -1179,6 +1185,10 @@
 	return ctx.mod.ApexName()
 }
 
+func (ctx *moduleContextImpl) apexSdkVersion() int {
+	return ctx.mod.ApexProperties.Info.MinSdkVersion
+}
+
 func (ctx *moduleContextImpl) hasStubsVariants() bool {
 	return ctx.mod.HasStubsVariants()
 }
diff --git a/cc/compiler.go b/cc/compiler.go
index 3a87b69..fe81bd0 100644
--- a/cc/compiler.go
+++ b/cc/compiler.go
@@ -315,6 +315,18 @@
 			"-isystem "+getCurrentIncludePath(ctx).Join(ctx, config.NDKTriple(tc)).String())
 	}
 
+	if ctx.canUseSdk() {
+		sdkVersion := ctx.sdkVersion()
+		if sdkVersion == "" || sdkVersion == "current" {
+			if ctx.isForPlatform() {
+				sdkVersion = strconv.Itoa(android.FutureApiLevel)
+			} else {
+				sdkVersion = strconv.Itoa(ctx.apexSdkVersion())
+			}
+		}
+		flags.Global.CommonFlags = append(flags.Global.CommonFlags, "-D__ANDROID_SDK_VERSION__="+sdkVersion)
+	}
+
 	if ctx.useVndk() {
 		flags.Global.CommonFlags = append(flags.Global.CommonFlags, "-D__ANDROID_VNDK__")
 	}