Add SourceProviders and a rust_bindgen module type

Add SourceProvider modules which provides a base interface for more
complex code generation usecases such as bindgen. Also adds the
rust_bindgen module type which calls bindgen to generate Rust FFI
bindings to C.

Bug: 159064919
Test: Local test module generates bindings.
Test: New Soong tests pass.

Change-Id: Ie31467bbbe423497666ad837cf5fe1acd1e76bd8

rust/bindgen_test.go

@@ -0,0 +1,56 @@
+// Copyright 2020 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"
+)
+
+func TestRustBindgen(t *testing.T) {
+	ctx := testRust(t, `
+		rust_bindgen {
+			name: "libbindgen",
+			wrapper_src: "src/any.h",
+			stem: "bindings",
+			flags: ["--bindgen-flag"],
+			cflags: ["--clang-flag"],
+			shared_libs: ["libfoo_shared"],
+			static_libs: ["libfoo_static"],
+		}
+		cc_library_shared {
+			name: "libfoo_shared",
+			export_include_dirs: ["shared_include"],
+		}
+		cc_library_static {
+			name: "libfoo_static",
+			export_include_dirs: ["static_include"],
+		}
+
+	`)
+	libbindgen := ctx.ModuleForTests("libbindgen", "android_arm64_armv8-a").Output("bindings.rs")
+	if !strings.Contains(libbindgen.Args["flags"], "--bindgen-flag") {
+		t.Errorf("missing bindgen flags in rust_bindgen rule: flags %#v", libbindgen.Args["flags"])
+	}
+	if !strings.Contains(libbindgen.Args["cflags"], "--clang-flag") {
+		t.Errorf("missing clang cflags in rust_bindgen rule: cflags %#v", libbindgen.Args["cflags"])
+	}
+	if !strings.Contains(libbindgen.Args["cflags"], "-Ishared_include") {
+		t.Errorf("missing clang cflags in rust_bindgen rule: cflags %#v", libbindgen.Args["cflags"])
+	}
+	if !strings.Contains(libbindgen.Args["cflags"], "-Istatic_include") {
+		t.Errorf("missing clang cflags in rust_bindgen rule: cflags %#v", libbindgen.Args["cflags"])
+	}
+}