Refactor cc modules to use decorators instead of inheritance

For example , instead of trying to have libraryLinker inherit from
baseLinker and libraryCompiler inherit from baseCompiler, create a
single decorator object that wraps both baseLinker and baseCompiler.

Test: Builds, no unexpected changes to build.ninja
Change-Id: I2468adaea8466c203a240259ba5694b8b1df7a52

cc/toolchain_library.go

@@ -0,0 +1,76 @@
+// Copyright 2016 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cc
+
+import (
+	"github.com/google/blueprint"
+	"github.com/google/blueprint/proptools"
+
+	"android/soong"
+	"android/soong/android"
+)
+
+//
+// Device libraries shipped with gcc
+//
+
+func init() {
+	soong.RegisterModuleType("toolchain_library", toolchainLibraryFactory)
+}
+
+type toolchainLibraryDecorator struct {
+	*libraryDecorator
+}
+
+func (*toolchainLibraryDecorator) linkerDeps(ctx BaseModuleContext, deps Deps) Deps {
+	// toolchain libraries can't have any dependencies
+	return deps
+}
+
+func toolchainLibraryFactory() (blueprint.Module, []interface{}) {
+	module, library := NewLibrary(android.DeviceSupported, false, true)
+	toolchainLibrary := &toolchainLibraryDecorator{
+		libraryDecorator: library,
+	}
+	module.compiler = toolchainLibrary
+	module.linker = toolchainLibrary
+	module.Properties.Clang = proptools.BoolPtr(false)
+	module.stl = nil
+	module.sanitize = nil
+	module.installer = nil
+	return module.Init()
+}
+
+func (library *toolchainLibraryDecorator) compile(ctx ModuleContext, flags Flags,
+	deps PathDeps) android.Paths {
+	return nil
+}
+
+func (library *toolchainLibraryDecorator) link(ctx ModuleContext,
+	flags Flags, deps PathDeps, objFiles android.Paths) android.Path {
+
+	libName := ctx.ModuleName() + staticLibraryExtension
+	outputFile := android.PathForModuleOut(ctx, libName)
+
+	if flags.Clang {
+		ctx.ModuleErrorf("toolchain_library must use GCC, not Clang")
+	}
+
+	CopyGccLib(ctx, libName, flagsToBuilderFlags(flags), outputFile)
+
+	ctx.CheckbuildFile(outputFile)
+
+	return outputFile
+}