versioning macro is exported from prebuilt stubs as well

This change fixes a bug that the versioning macro (__LIBNAME_API__) is
omitted for prebuilts providing a stub.

Bug: 175166063
Test: m nothing

Change-Id: I1cce5ab58ef245622861200ec0d8b0f84e3178ed

cc/library.go

@@ -1274,9 +1274,7 @@ func (library *libraryDecorator) link(ctx ModuleContext,
 	}
 
 	// Add stub-related flags if this library is a stub library.
-	if library.buildStubs() && !library.skipAPIDefine {
-		library.reexportFlags("-D" + versioningMacroName(ctx.Module().(*Module).ImplementationModuleName(ctx)) + "=" + library.stubsVersion())
-	}
+	library.exportVersioningMacroIfNeeded(ctx)
 
 	// Propagate a Provider containing information about exported flags, deps, and include paths.
 	library.flagExporter.setProvider(ctx)
@@ -1284,6 +1282,14 @@ func (library *libraryDecorator) link(ctx ModuleContext,
 	return out
 }
 
+func (library *libraryDecorator) exportVersioningMacroIfNeeded(ctx android.BaseModuleContext) {
+	if library.buildStubs() && !library.skipAPIDefine {
+		name := versioningMacroName(ctx.Module().(*Module).ImplementationModuleName(ctx))
+		ver := library.stubsVersion()
+		library.reexportFlags("-D" + name + "=" + ver)
+	}
+}
+
 // buildStatic returns true if this library should be built as a static library.
 func (library *libraryDecorator) buildStatic() bool {
 	return library.MutatedProperties.BuildStatic &&

cc/prebuilt.go

@@ -17,6 +17,7 @@ package cc
 import (
 	"android/soong/android"
 	"path/filepath"
+	"strings"
 )
 
 func init() {
@@ -117,6 +118,8 @@ func (p *prebuiltLibraryLinker) link(ctx ModuleContext,
 			return nil
 		}
 
+		p.libraryDecorator.exportVersioningMacroIfNeeded(ctx)
+
 		in := android.PathForModuleSrc(ctx, srcs[0])
 
 		if p.static() {
@@ -220,6 +223,11 @@ func (p *prebuiltLibraryLinker) disablePrebuilt() {
 	p.properties.Srcs = nil
 }
 
+// Implements versionedInterface
+func (p *prebuiltLibraryLinker) implementationModuleName(name string) string {
+	return strings.TrimPrefix(name, "prebuilt_")
+}
+
 func NewPrebuiltLibrary(hod android.HostOrDeviceSupported) (*Module, *libraryDecorator) {
 	module, library := NewLibrary(hod)
 	module.compiler = nil