Add Rust support to Soong.

Adds support to Soong for building rust modules. This currently only
supports x86_64 device and x86 linux host targets. The functionality
is sufficient to build crosvm.

Bug: 136189233
Test: Test module builds.
Test: crosvm builds.
Change-Id: I6ea04615834a6d673578ab10ea1a2eb04259fe09
diff --git a/rust/compiler_test.go b/rust/compiler_test.go
new file mode 100644
index 0000000..5369096
--- /dev/null
+++ b/rust/compiler_test.go
@@ -0,0 +1,77 @@
+// Copyright 2019 The Android Open Source Project
+//
+// 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 rust
+
+import (
+	"strings"
+	"testing"
+)
+
+// Test that feature flags are being correctly generated.
+func TestFeaturesToFlags(t *testing.T) {
+	ctx := testRust(t, `
+		rust_library_host_dylib {
+			name: "libfoo",
+			srcs: ["foo.rs"],
+			crate_name: "foo",
+			features: [
+				"fizz",
+				"buzz"
+			],
+		}`)
+
+	libfooDylib := ctx.ModuleForTests("libfoo", "linux_glibc_x86_64_dylib").Rule("rustc")
+
+	if !strings.Contains(libfooDylib.Args["rustcFlags"], "cfg 'feature=\"fizz\"'") ||
+		!strings.Contains(libfooDylib.Args["rustcFlags"], "cfg 'feature=\"buzz\"'") {
+		t.Fatalf("missing fizz and buzz feature flags for libfoo dylib, rustcFlags: %#v", libfooDylib.Args["rustcFlags"])
+	}
+}
+
+// Test that we reject multiple source files.
+func TestEnforceSingleSourceFile(t *testing.T) {
+
+	singleSrcError := "srcs can only contain one path for rust modules"
+
+	// Test libraries
+	testRustError(t, singleSrcError, `
+		rust_library_host {
+			name: "foo-bar-library",
+			srcs: ["foo.rs", "src/bar.rs"],
+		}`)
+
+	// Test binaries
+	testRustError(t, singleSrcError, `
+			rust_binary_host {
+				name: "foo-bar-binary",
+				srcs: ["foo.rs", "src/bar.rs"],
+			}`)
+
+	// Test proc_macros
+	testRustError(t, singleSrcError, `
+		rust_proc_macro {
+			name: "foo-bar-proc-macro",
+			srcs: ["foo.rs", "src/bar.rs"],
+			host_supported: true,
+		}`)
+
+	// Test prebuilts
+	testRustError(t, singleSrcError, `
+		rust_prebuilt_dylib {
+			name: "foo-bar-prebuilt",
+			srcs: ["liby.so", "libz.so"],
+		  host_supported: true,
+		}`)
+}