Support cross-compiling Windows binaries on Linux

This defines another mutator between HostOrDevice and Arch that will
expand host modules into a module for each host type
(Darwin/Linux/Windows) that is currently being built.

Change-Id: I4c8ac6b616c229f6bd45ad8a35902652fb6a4fff
diff --git a/cc/x86_windows_host.go b/cc/x86_windows_host.go
new file mode 100644
index 0000000..70ce74d
--- /dev/null
+++ b/cc/x86_windows_host.go
@@ -0,0 +1,150 @@
+// Copyright 2015 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 (
+	"strings"
+
+	"android/soong/common"
+)
+
+var (
+	windowsCflags = []string{
+		"-fno-exceptions", // from build/core/combo/select.mk
+		"-Wno-multichar",  // from build/core/combo/select.mk
+
+		"-DUSE_MINGW",
+		"-DWIN32_LEAN_AND_MEAN",
+		"-Wno-unused-parameter",
+		"-m32",
+
+		// Workaround differences in inttypes.h between host and target.
+		//See bug 12708004.
+		"-D__STDC_FORMAT_MACROS",
+		"-D__STDC_CONSTANT_MACROS",
+
+		// Use C99-compliant printf functions (%zd).
+		"-D__USE_MINGW_ANSI_STDIO=1",
+		// Admit to using >= Win2K. Both are needed because of <_mingw.h>.
+		"-D_WIN32_WINNT=0x0500",
+		"-DWINVER=0x0500",
+		// Get 64-bit off_t and related functions.
+		"-D_FILE_OFFSET_BITS=64",
+
+		// HOST_RELEASE_CFLAGS
+		"-O2", // from build/core/combo/select.mk
+		"-g",  // from build/core/combo/select.mk
+		"-fno-strict-aliasing", // from build/core/combo/select.mk
+	}
+
+	windowsIncludeFlags = []string{
+		"-I${windowsGccRoot}/${windowsGccTriple}/include",
+		"-I${windowsGccRoot}/lib/gcc/${windowsGccTriple}/4.8.3/include",
+	}
+
+	windowsLdflags = []string{
+		"-m32",
+		"-L${windowsGccRoot}/${windowsGccTriple}",
+		"--enable-stdcall-fixup",
+	}
+)
+
+func init() {
+	pctx.StaticVariable("windowsGccVersion", "4.8")
+
+	pctx.StaticVariable("windowsGccRoot",
+		"${SrcDir}/prebuilts/gcc/${HostPrebuiltTag}/host/x86_64-w64-mingw32-${windowsGccVersion}")
+
+	pctx.StaticVariable("windowsGccTriple", "x86_64-w64-mingw32")
+
+	pctx.StaticVariable("windowsCflags", strings.Join(windowsCflags, " "))
+	pctx.StaticVariable("windowsLdflags", strings.Join(windowsLdflags, " "))
+}
+
+type toolchainWindows struct {
+	toolchain32Bit
+
+	cFlags, ldFlags string
+}
+
+func (t *toolchainWindows) Name() string {
+	return "x86"
+}
+
+func (t *toolchainWindows) GccRoot() string {
+	return "${windowsGccRoot}"
+}
+
+func (t *toolchainWindows) GccTriple() string {
+	return "${windowsGccTriple}"
+}
+
+func (t *toolchainWindows) GccVersion() string {
+	return "${windowsGccVersion}"
+}
+
+func (t *toolchainWindows) Cflags() string {
+	return "${windowsCflags}"
+}
+
+func (t *toolchainWindows) Cppflags() string {
+	return ""
+}
+
+func (t *toolchainWindows) Ldflags() string {
+	return "${windowsLdflags}"
+}
+
+func (t *toolchainWindows) IncludeFlags() string {
+	return ""
+}
+
+func (t *toolchainWindows) ClangSupported() bool {
+	return false
+}
+
+func (t *toolchainWindows) ClangTriple() string {
+	panic("Clang is not supported under mingw")
+}
+
+func (t *toolchainWindows) ClangCflags() string {
+	panic("Clang is not supported under mingw")
+}
+
+func (t *toolchainWindows) ClangCppflags() string {
+	panic("Clang is not supported under mingw")
+}
+
+func (t *toolchainWindows) ClangLdflags() string {
+	panic("Clang is not supported under mingw")
+}
+
+func (t *toolchainWindows) ShlibSuffix() string {
+	return ".dll"
+}
+
+func (t *toolchainWindows) ExecutableSuffix() string {
+	return ".exe"
+}
+
+var toolchainWindowsSingleton Toolchain = &toolchainWindows{}
+
+func windowsToolchainFactory(arch common.Arch) Toolchain {
+	return toolchainWindowsSingleton
+}
+
+func init() {
+	registerHostToolchainFactory(common.Windows, common.X86, windowsToolchainFactory)
+}