Add rust musl arm and arm64 toolchains

Add rust toolchain configurations for arm-linux-musleabihf and
aarch64-linux-musl.

Bug: 236052820
Test: builds with linux musl arm64 host cross configured
Change-Id: Icfa73a75eac710e955f71a073cb4b7bb1cdfcc7a

rust/config/arm_linux_host.go

@@ -0,0 +1,147 @@
+// Copyright 2022 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 config
+
+import (
+	"strings"
+
+	"android/soong/android"
+)
+
+var (
+	linuxArmRustflags   = []string{}
+	linuxArmLinkflags   = []string{}
+	linuxArm64Rustflags = []string{}
+	linuxArm64Linkflags = []string{}
+)
+
+func init() {
+	registerToolchainFactory(android.LinuxMusl, android.Arm64, linuxMuslArm64ToolchainFactory)
+	registerToolchainFactory(android.LinuxMusl, android.Arm, linuxMuslArmToolchainFactory)
+
+	pctx.StaticVariable("LinuxToolchainArmRustFlags", strings.Join(linuxArmRustflags, " "))
+	pctx.StaticVariable("LinuxToolchainArmLinkFlags", strings.Join(linuxArmLinkflags, " "))
+	pctx.StaticVariable("LinuxToolchainArm64RustFlags", strings.Join(linuxArm64Rustflags, " "))
+	pctx.StaticVariable("LinuxToolchainArm64LinkFlags", strings.Join(linuxArm64Linkflags, " "))
+}
+
+// Base 64-bit linux rust toolchain
+type toolchainLinuxArm64 struct {
+	toolchain64Bit
+}
+
+func (toolchainLinuxArm64) Supported() bool {
+	return true
+}
+
+func (toolchainLinuxArm64) Bionic() bool {
+	return false
+}
+
+func (t *toolchainLinuxArm64) Name() string {
+	return "arm64"
+}
+
+func (t *toolchainLinuxArm64) ToolchainLinkFlags() string {
+	// Prepend the lld flags from cc_config so we stay in sync with cc
+	return "${cc_config.LinuxLldflags} ${cc_config.LinuxArm64Lldflags} " +
+		"${config.LinuxToolchainLinkFlags} ${config.LinuxToolchainArm64LinkFlags}"
+}
+
+func (t *toolchainLinuxArm64) ToolchainRustFlags() string {
+	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainArm64RustFlags}"
+}
+
+// Specialization of the 64-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslArm64 struct {
+	toolchainLinuxArm64
+}
+
+func (t *toolchainLinuxMuslArm64) RustTriple() string {
+	return "aarch64-unknown-linux-musl"
+}
+
+func (t *toolchainLinuxMuslArm64) ToolchainLinkFlags() string {
+	return t.toolchainLinuxArm64.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslArm64) ToolchainRustFlags() string {
+	return t.toolchainLinuxArm64.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslArm64ToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslArm64Singleton
+}
+
+// Base 32-bit linux rust toolchain
+type toolchainLinuxArm struct {
+	toolchain32Bit
+}
+
+func (toolchainLinuxArm) Supported() bool {
+	return true
+}
+
+func (toolchainLinuxArm) Bionic() bool {
+	return false
+}
+
+func (t *toolchainLinuxArm) Name() string {
+	return "arm"
+}
+
+func (toolchainLinuxArm) LibclangRuntimeLibraryArch() string {
+	return "arm"
+}
+
+func (toolchainLinuxArm64) LibclangRuntimeLibraryArch() string {
+	return "arm64"
+}
+
+func (t *toolchainLinuxArm) ToolchainLinkFlags() string {
+	// Prepend the lld flags from cc_config so we stay in sync with cc
+	return "${cc_config.LinuxLldflags} ${cc_config.LinuxArmLldflags} " +
+		"${config.LinuxToolchainLinkFlags} ${config.LinuxToolchainArmLinkFlags}"
+}
+
+func (t *toolchainLinuxArm) ToolchainRustFlags() string {
+	return "${config.LinuxToolchainRustFlags} ${config.LinuxToolchainArmRustFlags}"
+}
+
+// Specialization of the 32-bit linux rust toolchain for musl.  Adds the musl rust triple and
+// linker flags to avoid using the host sysroot.
+type toolchainLinuxMuslArm struct {
+	toolchainLinuxArm
+}
+
+func (t *toolchainLinuxMuslArm) RustTriple() string {
+	return "arm-unknown-linux-musleabihf"
+}
+
+func (t *toolchainLinuxMuslArm) ToolchainLinkFlags() string {
+	return t.toolchainLinuxArm.ToolchainLinkFlags() + " " + "${config.LinuxMuslToolchainLinkFlags}"
+}
+
+func (t *toolchainLinuxMuslArm) ToolchainRustFlags() string {
+	return t.toolchainLinuxArm.ToolchainRustFlags() + " " + "${config.LinuxMuslToolchainRustFlags}"
+}
+
+func linuxMuslArmToolchainFactory(arch android.Arch) Toolchain {
+	return toolchainLinuxMuslArmSingleton
+}
+
+var toolchainLinuxMuslArm64Singleton Toolchain = &toolchainLinuxMuslArm64{}
+var toolchainLinuxMuslArmSingleton Toolchain = &toolchainLinuxMuslArm{}