bp2build: allowlist //external/libcap/...

This builds cap_names.list.h, which uses an eponymous filegroup
"generate_cap_names_list.awk" in Soong, but uses the file target
directly in Bazel.

This also improve filegroup support for mixed builds, by issuing a
cquery call _without_ arch. Filegroups in Soong don't have configurable
properties, so don't generate Bazel filegroups into buildroot's
config_nodes (which was x86_64 by default).

The mixed_build_root now looks like this:

```
config_node(...)
config_node(...)
config_node(...)
config_node(...)

...

filegroup(name = "common",
    srcs = ["@//bionic/linker:linker_sources_x86",
            "@//bionic/libc:kernel_input_headers",
            "@//system/timezone/apex:com.android.tzdata-androidManifest",
            "@//external/libcap:generate_cap_names_list.awk",
            "@//bionic/linker:linker_sources_arm64",
            "@//bionic/linker:linker_sources",
            "@//bionic/libc:libc_sources_shared_arm",
            "@//bionic/linker:linker_sources_x86_64",
            "@//bionic/libc:all_kernel_uapi_headers",
            "@//build/bazel/examples/apex/minimal:build.bazel.examples.apex.minimal-file_contexts",
            "@//system/core/libcutils:android_filesystem_config_header",
            "@//bionic/libc:libc_sources_static",
            "@//bionic/linker:linker_sources_arm",
            "@//bionic/libc/tools:bionic-gensyscalls",
            "@//bionic/tools:bionic-generate-version-script",
            "@//bionic/libc:libc_sources_shared"],
)

mixed_build_root(name = "buildroot",
    deps = [":x86",
            ":arm64",
            ":arm",
            ":common",
            ":x86_64"],
)
```

Test: CI
Fixes: 198595323
Fixes: 198235838
Change-Id: I6df9a14da556cf358d96e6a99b514f66a2638295

android/bazel.go

@@ -182,6 +182,7 @@ var (
 		"external/jemalloc_new":           Bp2BuildDefaultTrueRecursively,
 		"external/libcxx":                 Bp2BuildDefaultTrueRecursively,
 		"external/libcxxabi":              Bp2BuildDefaultTrueRecursively,
+		"external/libcap":                 Bp2BuildDefaultTrueRecursively,
 		"external/scudo":                  Bp2BuildDefaultTrueRecursively,
 		"prebuilts/clang/host/linux-x86":  Bp2BuildDefaultTrueRecursively,
 	}
@@ -231,6 +232,10 @@ var (
 		//external/brotli/...
 		"brotli-fuzzer-corpus", // "declared output 'external/brotli/c/fuzz/73231c6592f195ffd41100b8706d1138ff6893b9' was not created by genrule"
 
+		// //external/libcap/...
+		"libcap",      // http://b/198595332, depends on _makenames, a cc_binary
+		"cap_names.h", // http://b/198596102, depends on _makenames, a cc_binary
+
 		// Tests. Handle later.
 		"libbionic_tests_headers_posix", // http://b/186024507, cc_library_static, sched.h, time.h not found
 		"libjemalloc5_integrationtest",

android/bazel_handler.go

@@ -27,9 +27,9 @@ import (
 	"sync"
 
 	"android/soong/bazel/cquery"
+	"android/soong/shared"
 
 	"android/soong/bazel"
-	"android/soong/shared"
 )
 
 type cqueryRequest interface {
@@ -490,6 +490,12 @@ config_node(name = "%s",
     arch = "%s",
     deps = [%s],
 )
+`
+
+	commonArchFilegroupString := `
+filegroup(name = "common",
+    srcs = [%s],
+)
 `
 
 	configNodesSection := ""
@@ -501,14 +507,22 @@ config_node(name = "%s",
 		labelsByArch[archString] = append(labelsByArch[archString], labelString)
 	}
 
-	configNodeLabels := []string{}
+	allLabels := []string{}
 	for archString, labels := range labelsByArch {
-		configNodeLabels = append(configNodeLabels, fmt.Sprintf("\":%s\"", archString))
-		labelsString := strings.Join(labels, ",\n            ")
-		configNodesSection += fmt.Sprintf(configNodeFormatString, archString, archString, labelsString)
+		if archString == "common" {
+			// arch-less labels (e.g. filegroups) don't need a config_node
+			allLabels = append(allLabels, "\":common\"")
+			labelsString := strings.Join(labels, ",\n            ")
+			configNodesSection += fmt.Sprintf(commonArchFilegroupString, labelsString)
+		} else {
+			// Create a config_node, and add the config_node's label to allLabels
+			allLabels = append(allLabels, fmt.Sprintf("\":%s\"", archString))
+			labelsString := strings.Join(labels, ",\n            ")
+			configNodesSection += fmt.Sprintf(configNodeFormatString, archString, archString, labelsString)
+		}
 	}
 
-	return []byte(fmt.Sprintf(formatString, configNodesSection, strings.Join(configNodeLabels, ",\n            ")))
+	return []byte(fmt.Sprintf(formatString, configNodesSection, strings.Join(allLabels, ",\n            ")))
 }
 
 func indent(original string) string {
@@ -573,6 +587,12 @@ def %s(target):
 %s
 
 def get_arch(target):
+  # TODO(b/199363072): filegroups and file targets aren't associated with any
+  # specific platform architecture in mixed builds. This is consistent with how
+  # Soong treats filegroups, but it may not be the case with manually-written
+  # filegroup BUILD targets.
+  if target.kind in ["filegroup", ""]:
+    return "common"
   buildoptions = build_options(target)
   platforms = build_options(target)["//command_line_option:platforms"]
   if len(platforms) != 1:
@@ -671,11 +691,12 @@ func (context *bazelContext) InvokeBazel() error {
 	if err != nil {
 		return err
 	}
+
 	buildrootLabel := "@soong_injection//mixed_builds:buildroot"
 	cqueryOutput, cqueryErr, err = context.issueBazelCommand(
 		context.paths,
 		bazel.CqueryBuildRootRunName,
-		bazelCommand{"cquery", fmt.Sprintf("kind(rule, deps(%s))", buildrootLabel)},
+		bazelCommand{"cquery", fmt.Sprintf("deps(%s)", buildrootLabel)},
 		"--output=starlark",
 		"--starlark:file="+absolutePath(cqueryFileRelpath))
 	err = ioutil.WriteFile(filepath.Join(soongInjectionPath, "cquery.out"),

android/bazel_handler_test.go

@@ -11,7 +11,7 @@ func TestRequestResultsAfterInvokeBazel(t *testing.T) {
 	label := "//foo:bar"
 	arch := Arm64
 	bazelContext, _ := testBazelContext(t, map[bazelCommand]string{
-		bazelCommand{command: "cquery", expression: "kind(rule, deps(@soong_injection//mixed_builds:buildroot))"}: `//foo:bar|arm64>>out/foo/bar.txt`,
+		bazelCommand{command: "cquery", expression: "deps(@soong_injection//mixed_builds:buildroot)"}: `//foo:bar|arm64>>out/foo/bar.txt`,
 	})
 	g, ok := bazelContext.GetOutputFiles(label, arch)
 	if ok {

android/filegroup.go

@@ -118,7 +118,7 @@ func (fg *fileGroup) GenerateBazelBuildActions(ctx ModuleContext) bool {
 	}
 
 	bazelCtx := ctx.Config().BazelContext
-	filePaths, ok := bazelCtx.GetOutputFiles(fg.GetBazelLabel(ctx, fg), ctx.Arch().ArchType)
+	filePaths, ok := bazelCtx.GetOutputFiles(fg.GetBazelLabel(ctx, fg), Common)
 	if !ok {
 		return false
 	}