Make OutputFileForModule work for AllowMissingDependencies

Report missing output files as missing dependencies when
AllowMissingDependencies is enabled.  This will fix
AllowMissingDependencies builds where a dependency module is
present but missing support for a specific architecture.

Bug: 250918230
Test: lunch aosp_riscv64-userdebug && m ALLOW_MISSING_DEPENDENCIES=true nothing
Test: TestOutputFileForModule
Change-Id: I95e96e3e7cb3df7bf678ed628b45baf659addbad

android/android_test.go

@@ -15,10 +15,32 @@
 package android
 
 import (
+	"io/ioutil"
 	"os"
 	"testing"
 )
 
-func TestMain(m *testing.M) {
-	os.Exit(m.Run())
+var buildDir string
+
+func setUp() {
+	var err error
+	buildDir, err = ioutil.TempDir("", "android_test")
+	if err != nil {
+		panic(err)
+	}
+}
+
+func tearDown() {
+	os.RemoveAll(buildDir)
+}
+
+func TestMain(m *testing.M) {
+	run := func() int {
+		setUp()
+		defer tearDown()
+
+		return m.Run()
+	}
+
+	os.Exit(run())
 }

android/module.go

@@ -3546,10 +3546,29 @@ func OutputFileForModule(ctx PathContext, module blueprint.Module, tag string) P
 		reportPathError(ctx, err)
 		return nil
 	}
+	if len(paths) == 0 {
+		type addMissingDependenciesIntf interface {
+			AddMissingDependencies([]string)
+			OtherModuleName(blueprint.Module) string
+		}
+		if mctx, ok := ctx.(addMissingDependenciesIntf); ok && ctx.Config().AllowMissingDependencies() {
+			mctx.AddMissingDependencies([]string{mctx.OtherModuleName(module)})
+		} else {
+			ReportPathErrorf(ctx, "failed to get output files from module %q", pathContextName(ctx, module))
+		}
+		// Return a fake output file to avoid nil dereferences of Path objects later.
+		// This should never get used for an actual build as the error or missing
+		// dependency has already been reported.
+		p, err := pathForSource(ctx, filepath.Join("missing_output_file", pathContextName(ctx, module)))
+		if err != nil {
+			reportPathError(ctx, err)
+			return nil
+		}
+		return p
+	}
 	if len(paths) > 1 {
 		ReportPathErrorf(ctx, "got multiple output files from module %q, expected exactly one",
 			pathContextName(ctx, module))
-		return nil
 	}
 	return paths[0]
 }
@@ -3561,18 +3580,12 @@ func outputFilesForModule(ctx PathContext, module blueprint.Module, tag string)
 			return nil, fmt.Errorf("failed to get output file from module %q: %s",
 				pathContextName(ctx, module), err.Error())
 		}
-		if len(paths) == 0 {
-			return nil, fmt.Errorf("failed to get output files from module %q", pathContextName(ctx, module))
-		}
 		return paths, nil
 	} else if sourceFileProducer, ok := module.(SourceFileProducer); ok {
 		if tag != "" {
 			return nil, fmt.Errorf("module %q is a SourceFileProducer, not an OutputFileProducer, and so does not support tag %q", pathContextName(ctx, module), tag)
 		}
 		paths := sourceFileProducer.Srcs()
-		if len(paths) == 0 {
-			return nil, fmt.Errorf("failed to get output files from module %q", pathContextName(ctx, module))
-		}
 		return paths, nil
 	} else {
 		return nil, fmt.Errorf("module %q is not an OutputFileProducer", pathContextName(ctx, module))

android/module_test.go

@@ -15,6 +15,7 @@
 package android
 
 import (
+	"github.com/google/blueprint"
 	"path/filepath"
 	"runtime"
 	"testing"
@@ -978,3 +979,88 @@ func TestSetAndroidMkEntriesWithTestOptions(t *testing.T) {
 		})
 	}
 }
+
+type fakeBlueprintModule struct{}
+
+func (fakeBlueprintModule) Name() string { return "foo" }
+
+func (fakeBlueprintModule) GenerateBuildActions(blueprint.ModuleContext) {}
+
+type sourceProducerTestModule struct {
+	fakeBlueprintModule
+	source Path
+}
+
+func (s sourceProducerTestModule) Srcs() Paths { return Paths{s.source} }
+
+type outputFileProducerTestModule struct {
+	fakeBlueprintModule
+	output map[string]Path
+	error  map[string]error
+}
+
+func (o outputFileProducerTestModule) OutputFiles(tag string) (Paths, error) {
+	return PathsIfNonNil(o.output[tag]), o.error[tag]
+}
+
+type pathContextAddMissingDependenciesWrapper struct {
+	PathContext
+	missingDeps []string
+}
+
+func (p *pathContextAddMissingDependenciesWrapper) AddMissingDependencies(deps []string) {
+	p.missingDeps = append(p.missingDeps, deps...)
+}
+func (p *pathContextAddMissingDependenciesWrapper) OtherModuleName(module blueprint.Module) string {
+	return module.Name()
+}
+
+func TestOutputFileForModule(t *testing.T) {
+	testcases := []struct {
+		name        string
+		module      blueprint.Module
+		tag         string
+		env         map[string]string
+		config      func(*config)
+		expected    string
+		missingDeps []string
+	}{
+		{
+			name:     "SourceFileProducer",
+			module:   &sourceProducerTestModule{source: PathForTesting("foo.txt")},
+			expected: "foo.txt",
+		},
+		{
+			name:     "OutputFileProducer",
+			module:   &outputFileProducerTestModule{output: map[string]Path{"": PathForTesting("foo.txt")}},
+			expected: "foo.txt",
+		},
+		{
+			name:     "OutputFileProducer_tag",
+			module:   &outputFileProducerTestModule{output: map[string]Path{"foo": PathForTesting("foo.txt")}},
+			tag:      "foo",
+			expected: "foo.txt",
+		},
+		{
+			name: "OutputFileProducer_AllowMissingDependencies",
+			config: func(config *config) {
+				config.TestProductVariables.Allow_missing_dependencies = boolPtr(true)
+			},
+			module:      &outputFileProducerTestModule{},
+			missingDeps: []string{"foo"},
+			expected:    "missing_output_file/foo",
+		},
+	}
+	for _, tt := range testcases {
+		config := TestConfig(buildDir, tt.env, "", nil)
+		if tt.config != nil {
+			tt.config(config.config)
+		}
+		ctx := &pathContextAddMissingDependenciesWrapper{
+			PathContext: PathContextForTesting(config),
+		}
+		got := OutputFileForModule(ctx, tt.module, tt.tag)
+		AssertPathRelativeToTopEquals(t, "expected source path", tt.expected, got)
+		AssertArrayString(t, "expected missing deps", tt.missingDeps, ctx.missingDeps)
+	}
+}