bp2build: cc_object converter.

This CL introduces a basic bp2build converter for cc_object modules.
cc_objects maps cleanly to cc_library targets, but with -fnoaddrsig.

This CL also demonstrates generating include deps within a macro to
allow the cc_object compilation to depend on a relative-include header
within an include dir.

e.g. if "foo.cc" includes "android/log.h" and the latter is located at
"include/android/log.h", the autogenerated header deps would export
"android/log.h" correctly to the foo.cc upstream target.

Test: GENERATE_BAZEL_FILES=true m nothing && bp2build-sync write && bazel build //bionic/libc:crtbegin_so1

Change-Id: Ifd9e097051ec184ab0a1929d07918f0ff4f24d98
diff --git a/bp2build/cc_object_conversion_test.go b/bp2build/cc_object_conversion_test.go
new file mode 100644
index 0000000..e4ffe16
--- /dev/null
+++ b/bp2build/cc_object_conversion_test.go
@@ -0,0 +1,186 @@
+// Copyright 2021 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 bp2build
+
+import (
+	"android/soong/android"
+	"android/soong/cc"
+	"fmt"
+	"strings"
+	"testing"
+)
+
+func TestCcObjectBp2Build(t *testing.T) {
+	testCases := []struct {
+		description                        string
+		moduleTypeUnderTest                string
+		moduleTypeUnderTestFactory         android.ModuleFactory
+		moduleTypeUnderTestBp2BuildMutator func(android.TopDownMutatorContext)
+		blueprint                          string
+		expectedBazelTargets               []string
+		filesystem                         map[string]string
+	}{
+		{
+			description:                        "simple cc_object generates cc_object with include header dep",
+			moduleTypeUnderTest:                "cc_object",
+			moduleTypeUnderTestFactory:         cc.ObjectFactory,
+			moduleTypeUnderTestBp2BuildMutator: cc.ObjectBp2Build,
+			filesystem: map[string]string{
+				"a/b/foo.h": "",
+				"a/b/bar.h": "",
+				"a/b/c.c":   "",
+			},
+			blueprint: `cc_object {
+    name: "foo",
+    local_include_dirs: ["include"],
+    cflags: [
+        "-Wno-gcc-compat",
+        "-Wall",
+        "-Werror",
+    ],
+    srcs: [
+        "a/b/*.h",
+        "a/b/c.c"
+    ],
+
+    bazel_module: { bp2build_available: true },
+}
+`,
+			expectedBazelTargets: []string{`cc_object(
+    name = "foo",
+    copts = [
+        "-fno-addrsig",
+        "-Wno-gcc-compat",
+        "-Wall",
+        "-Werror",
+    ],
+    local_include_dirs = [
+        "include",
+    ],
+    srcs = [
+        "a/b/bar.h",
+        "a/b/foo.h",
+        "a/b/c.c",
+    ],
+)`,
+			},
+		},
+		{
+			description:                        "simple cc_object with defaults",
+			moduleTypeUnderTest:                "cc_object",
+			moduleTypeUnderTestFactory:         cc.ObjectFactory,
+			moduleTypeUnderTestBp2BuildMutator: cc.ObjectBp2Build,
+			blueprint: `cc_object {
+    name: "foo",
+    local_include_dirs: ["include"],
+    srcs: [
+        "a/b/*.h",
+        "a/b/c.c"
+    ],
+
+    defaults: ["foo_defaults"],
+    bazel_module: { bp2build_available: true },
+}
+
+cc_defaults {
+    name: "foo_defaults",
+    defaults: ["foo_bar_defaults"],
+	// TODO(b/178130668): handle configurable attributes that depend on the platform
+    arch: {
+        x86: {
+            cflags: ["-fPIC"],
+        },
+        x86_64: {
+            cflags: ["-fPIC"],
+        },
+    },
+}
+
+cc_defaults {
+    name: "foo_bar_defaults",
+    cflags: [
+        "-Wno-gcc-compat",
+        "-Wall",
+        "-Werror",
+    ],
+}
+`,
+			expectedBazelTargets: []string{`cc_object(
+    name = "foo",
+    copts = [
+        "-Wno-gcc-compat",
+        "-Wall",
+        "-Werror",
+        "-fno-addrsig",
+    ],
+    local_include_dirs = [
+        "include",
+    ],
+    srcs = [
+        "a/b/c.c",
+    ],
+)`,
+			},
+		},
+	}
+
+	dir := "."
+	for _, testCase := range testCases {
+		filesystem := make(map[string][]byte)
+		toParse := []string{
+			"Android.bp",
+		}
+		for f, content := range testCase.filesystem {
+			if strings.HasSuffix(f, "Android.bp") {
+				toParse = append(toParse, f)
+			}
+			filesystem[f] = []byte(content)
+		}
+		config := android.TestConfig(buildDir, nil, testCase.blueprint, filesystem)
+		ctx := android.NewTestContext(config)
+		// Always register cc_defaults module factory
+		ctx.RegisterModuleType("cc_defaults", func() android.Module { return cc.DefaultsFactory() })
+
+		ctx.RegisterModuleType(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestFactory)
+		ctx.RegisterBp2BuildMutator(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestBp2BuildMutator)
+		ctx.RegisterForBazelConversion()
+
+		_, errs := ctx.ParseFileList(dir, toParse)
+		if Errored(t, testCase.description, errs) {
+			continue
+		}
+		_, errs = ctx.ResolveDependencies(config)
+		if Errored(t, testCase.description, errs) {
+			continue
+		}
+
+		bazelTargets := GenerateBazelTargets(ctx.Context.Context, Bp2Build)[dir]
+		if actualCount, expectedCount := len(bazelTargets), len(testCase.expectedBazelTargets); actualCount != expectedCount {
+			fmt.Println(bazelTargets)
+			t.Errorf("%s: Expected %d bazel target, got %d", testCase.description, expectedCount, actualCount)
+		} else {
+			for i, target := range bazelTargets {
+				if w, g := testCase.expectedBazelTargets[i], target.content; w != g {
+					t.Errorf(
+						"%s: Expected generated Bazel target to be '%s', got '%s'",
+						testCase.description,
+						w,
+						g,
+					)
+				}
+			}
+		}
+	}
+}