Add clippy-driver build rule

Depending on the location of the repository (e.g. external/, vendor/), a
different set of lints will be enabled. Add the clippy property to the
rust_* modules. This property can be used to overwrite the default
behaviour.

Test: m checkbuild
Bug: 157238651
Change-Id: Ife0f723ef4a74abb102597f8486a7b9f30e7d351

rust/clippy_test.go

@@ -0,0 +1,46 @@
+// 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 (
+	"testing"
+)
+
+func TestClippy(t *testing.T) {
+	ctx := testRust(t, `
+		rust_library {
+			name: "libfoo",
+			srcs: ["foo.rs"],
+			crate_name: "foo",
+		}
+		rust_library {
+			name: "libfoobar",
+			srcs: ["foo.rs"],
+			crate_name: "foobar",
+			clippy: false,
+		}`)
+
+	ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_shared").Output("libfoo.so")
+	fooClippy := ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_shared").MaybeRule("clippy")
+	if fooClippy.Rule.String() != "android/soong/rust.clippy" {
+		t.Errorf("Clippy output (default) for libfoo was not generated: %+v", fooClippy)
+	}
+
+	ctx.ModuleForTests("libfoobar", "android_arm64_armv8-a_shared").Output("libfoobar.so")
+	foobarClippy := ctx.ModuleForTests("libfoobar", "android_arm64_armv8-a_shared").MaybeRule("clippy")
+	if foobarClippy.Rule != nil {
+		t.Errorf("Clippy output for libfoobar is not empty")
+	}
+}