Versioned CRT objects are built with correct __ANDROID_API__

Background: `min_sdk_version` of a crt object is the oldest SDK version
that the crt object supports. When it's set to for example 16, Soong
creates a number of versioned variants of the crt object starting from
16 to the latest version. The variant for version X is provided to NDK
clients having `min_sdk_version` set to X.

Problem: all versioned variants of a crt object were built with `-target
<arch>-linux-android16`. Therefore they all have been with `#define __ANDROID_API__
16`.  This is because the mutated variants still have the same
min_sdk_version property and the clang triple follows min_sdk_version,
not sdk_version. This is too conservative and against our intention to
provide the latest crt object that matches with the min_sdk_version of
the client.

In the other hand, the platform(non-sdk) variant of the crt object
doesn't have such a problem. min_sdk_version is completely ignored.
However, this is a bug and will be fixed by aosp/1640364. As a side
effect of the fixing, the platform variant will begin to built with a
very old __ANDROID_API__ which unnecessarily turns off the new platform
features like the TLS segment over-alignment.

This change fixes the problems:

* For the versioned variants of crt objects, we set both
`min_sdk_version` and `sdk_versio` to the version that the variant is
created for.

* For the platform variant of crt objects, `min_sdk_version` is force
reset to "current".

Bug: 183191008
Test: m

Change-Id: I8c9d0fcea816de8cd1532dac4a47eee4f726c037

cc/cc.go

@@ -1363,6 +1363,19 @@ func (ctx *moduleContextImpl) minSdkVersion() string {
 	if ver == "apex_inherit" || ver == "" {
 		ver = ctx.sdkVersion()
 	}
+	// For crt objects, the meaning of min_sdk_version is very different from other types of
+	// module. For them, min_sdk_version defines the oldest version that the build system will
+	// create versioned variants for. For example, if min_sdk_version is 16, then sdk variant of
+	// the crt object has local variants of 16, 17, ..., up to the latest version. sdk_version
+	// and min_sdk_version properties of the variants are set to the corresponding version
+	// numbers. However, the platform (non-sdk) variant of the crt object is left untouched.
+	// min_sdk_version: 16 doesn't actually mean that the platform variant has to support such
+	// an old version. Since the variant is for the platform, it's preferred to target the
+	// latest version.
+	if ctx.mod.SplitPerApiLevel() && !ctx.isSdkVariant() {
+		ver = strconv.Itoa(android.FutureApiLevelInt)
+	}
+
 	// Also make sure that minSdkVersion is not greater than sdkVersion, if they are both numbers
 	sdkVersionInt, err := strconv.Atoi(ctx.sdkVersion())
 	minSdkVersionInt, err2 := strconv.Atoi(ver)
@@ -1933,9 +1946,14 @@ func GetCrtVariations(ctx android.BottomUpMutatorContext,
 		return nil
 	}
 	if m.UseSdk() {
+		// Choose the CRT that best satisfies the min_sdk_version requirement of this module
+		minSdkVersion := m.MinSdkVersion()
+		if minSdkVersion == "" || minSdkVersion == "apex_inherit" {
+			minSdkVersion = m.SdkVersion()
+		}
 		return []blueprint.Variation{
 			{Mutator: "sdk", Variation: "sdk"},
-			{Mutator: "version", Variation: m.SdkVersion()},
+			{Mutator: "version", Variation: minSdkVersion},
 		}
 	}
 	return []blueprint.Variation{

cc/cc_test.go

@@ -3640,6 +3640,59 @@ func TestMinSdkVersionInClangTriple(t *testing.T) {
 	android.AssertStringDoesContain(t, "min sdk version", cFlags, "-target aarch64-linux-android29")
 }
 
+func TestMinSdkVersionsOfCrtObjects(t *testing.T) {
+	ctx := testCc(t, `
+		cc_object {
+			name: "crt_foo",
+			srcs: ["foo.c"],
+			crt: true,
+			stl: "none",
+			min_sdk_version: "28",
+
+		}`)
+
+	arch := "android_arm64_armv8-a"
+	for _, v := range []string{"", "28", "29", "30", "current"} {
+		var variant string
+		if v == "" {
+			variant = arch
+		} else {
+			variant = arch + "_sdk_" + v
+		}
+		cflags := ctx.ModuleForTests("crt_foo", variant).Rule("cc").Args["cFlags"]
+		vNum := v
+		if v == "current" || v == "" {
+			vNum = "10000"
+		}
+		expected := "-target aarch64-linux-android" + vNum + " "
+		android.AssertStringDoesContain(t, "cflag", cflags, expected)
+	}
+}
+
+func TestUseCrtObjectOfCorrectVersion(t *testing.T) {
+	ctx := testCc(t, `
+		cc_binary {
+			name: "bin",
+			srcs: ["foo.c"],
+			stl: "none",
+			min_sdk_version: "29",
+			sdk_version: "current",
+		}
+		`)
+
+	// Sdk variant uses the crt object of the matching min_sdk_version
+	variant := "android_arm64_armv8-a_sdk"
+	crt := ctx.ModuleForTests("bin", variant).Rule("ld").Args["crtBegin"]
+	android.AssertStringDoesContain(t, "crt dep of sdk variant", crt,
+		variant+"_29/crtbegin_dynamic.o")
+
+	// platform variant uses the crt object built for platform
+	variant = "android_arm64_armv8-a"
+	crt = ctx.ModuleForTests("bin", variant).Rule("ld").Args["crtBegin"]
+	android.AssertStringDoesContain(t, "crt dep of platform variant", crt,
+		variant+"/crtbegin_dynamic.o")
+}
+
 type MemtagNoteType int
 
 const (

cc/library.go

@@ -1914,6 +1914,7 @@ func createPerApiVersionVariations(mctx android.BottomUpMutatorContext, minSdkVe
 
 	for i, module := range modules {
 		module.(*Module).Properties.Sdk_version = StringPtr(versionStrs[i])
+		module.(*Module).Properties.Min_sdk_version = StringPtr(versionStrs[i])
 	}
 }
 

cc/linkable.go

@@ -111,6 +111,7 @@ type LinkableInterface interface {
 	InProduct() bool
 
 	SdkVersion() string
+	MinSdkVersion() string
 	AlwaysSdk() bool
 	IsSdkVariant() bool
 

rust/rust.go

@@ -256,6 +256,10 @@ func (mod *Module) SdkVersion() string {
 	return ""
 }
 
+func (mod *Module) MinSdkVersion() string {
+	return ""
+}
+
 func (mod *Module) AlwaysSdk() bool {
 	return false
 }