Merge changes from topic "libbinder_ndk-remove-cpp-headers" into main

* changes:
  ndk_library: limit exports
  Reland "Truely re-export export_header_libs from ndk_library"
  ndk_library depends on the correct arch variant of cc_library_headers

android/neverallow.go

@@ -60,6 +60,7 @@ func init() {
 	AddNeverAllowRules(createCcStubsRule())
 	AddNeverAllowRules(createJavaExcludeStaticLibsRule())
 	AddNeverAllowRules(createProhibitHeaderOnlyRule())
+	AddNeverAllowRules(createLimitNdkExportRule()...)
 }
 
 // Add a NeverAllow rule to the set of rules to apply.
@@ -267,6 +268,22 @@ func createProhibitHeaderOnlyRule() Rule {
 		Because("headers_only can only be used for generating framework-minus-apex headers for non-updatable modules")
 }
 
+func createLimitNdkExportRule() []Rule {
+	reason := "If the headers you're trying to export are meant to be a part of the NDK, they should be exposed by an ndk_headers module. If the headers shouldn't be a part of the NDK, the headers should instead be exposed from a separate `cc_library_headers` which consumers depend on."
+	// DO NOT ADD HERE - please consult danalbert@
+	// b/357711733
+	return []Rule{
+		NeverAllow().
+			NotIn("frameworks/native/libs/binder/ndk").
+			ModuleType("ndk_library").
+			WithMatcher("export_header_libs", isSetMatcherInstance).Because(reason),
+		NeverAllow().ModuleType("ndk_library").WithMatcher("export_generated_headers", isSetMatcherInstance).Because(reason),
+		NeverAllow().ModuleType("ndk_library").WithMatcher("export_include_dirs", isSetMatcherInstance).Because(reason),
+		NeverAllow().ModuleType("ndk_library").WithMatcher("export_shared_lib_headers", isSetMatcherInstance).Because(reason),
+		NeverAllow().ModuleType("ndk_library").WithMatcher("export_static_lib_headers", isSetMatcherInstance).Because(reason),
+	}
+}
+
 func neverallowMutator(ctx BottomUpMutatorContext) {
 	m, ok := ctx.Module().(Module)
 	if !ok {

cc/cc.go

@@ -2507,8 +2507,14 @@ func (c *Module) DepsMutator(actx android.BottomUpMutatorContext) {
 		}
 
 		if c.isNDKStubLibrary() {
-			// ndk_headers do not have any variations
+			variationExists := actx.OtherModuleDependencyVariantExists(nil, lib)
-			actx.AddFarVariationDependencies([]blueprint.Variation{}, depTag, lib)
+			if variationExists {
+				actx.AddVariationDependencies(nil, depTag, lib)
+			} else {
+				// dependencies to ndk_headers fall here as ndk_headers do not have
+				// any variants.
+				actx.AddFarVariationDependencies([]blueprint.Variation{}, depTag, lib)
+			}
 		} else if c.IsStubs() && !c.isImportedApiLibrary() {
 			actx.AddFarVariationDependencies(append(ctx.Target().Variations(), c.ImageVariation()),
 				depTag, lib)

cc/ndk_library.go

@@ -493,7 +493,8 @@ func (c *stubDecorator) compile(ctx ModuleContext, flags Flags, deps PathDeps) O
 // Add a dependency on the header modules of this ndk_library
 func (linker *stubDecorator) linkerDeps(ctx DepsContext, deps Deps) Deps {
 	return Deps{
-		HeaderLibs: linker.properties.Export_header_libs,
+		ReexportHeaderLibHeaders: linker.properties.Export_header_libs,
+		HeaderLibs:               linker.properties.Export_header_libs,
 	}
 }