Syntax check generated Android.bp snapshot

Checks the syntax of the Android.bp file generated for the sdk
snapshot. While this will not detect all possible problems with the
generated Android.bp file it will detect some and it is far better to
detect those issues during generation than when it is unpacked and
used.

Bug: 155628860
Test: m nothing
Change-Id: Ieec86a7a49fa2e3bd8b9f83aca540114232a3476

android/module.go

@@ -104,6 +104,8 @@ type EarlyModuleContext interface {
 type BaseModuleContext interface {
 	EarlyModuleContext
 
+	blueprintBaseModuleContext() blueprint.BaseModuleContext
+
 	OtherModuleName(m blueprint.Module) string
 	OtherModuleDir(m blueprint.Module) string
 	OtherModuleErrorf(m blueprint.Module, fmt string, args ...interface{})
@@ -1442,6 +1444,10 @@ func (b *baseModuleContext) GetDirectDepWithTag(name string, tag blueprint.Depen
 	return b.bp.GetDirectDepWithTag(name, tag)
 }
 
+func (b *baseModuleContext) blueprintBaseModuleContext() blueprint.BaseModuleContext {
+	return b.bp
+}
+
 type moduleContext struct {
 	bp blueprint.ModuleContext
 	baseModuleContext
@@ -2364,3 +2370,8 @@ type IdeInfo struct {
 	Installed_paths   []string `json:"installed,omitempty"`
 	SrcJars           []string `json:"srcjars,omitempty"`
 }
+
+func CheckBlueprintSyntax(ctx BaseModuleContext, filename string, contents string) []error {
+	bpctx := ctx.blueprintBaseModuleContext()
+	return blueprint.CheckBlueprintSyntax(bpctx.ModuleFactories(), filename, contents)
+}

sdk/update.go

@@ -350,6 +350,9 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 	bp = newGeneratedFile(ctx, "snapshot", "Android.bp")
 	generateBpContents(&bp.generatedContents, bpFile)
 
+	contents := bp.content.String()
+	syntaxCheckSnapshotBpFile(ctx, contents)
+
 	bp.build(pctx, ctx, nil)
 
 	filesToZip := builder.filesToZip
@@ -394,6 +397,36 @@ func (s *sdk) buildSnapshot(ctx android.ModuleContext, sdkVariants []*sdk) andro
 	return outputZipFile
 }
 
+// Check the syntax of the generated Android.bp file contents and if they are
+// invalid then log an error with the contents (tagged with line numbers) and the
+// errors that were found so that it is easy to see where the problem lies.
+func syntaxCheckSnapshotBpFile(ctx android.ModuleContext, contents string) {
+	errs := android.CheckBlueprintSyntax(ctx, "Android.bp", contents)
+	if len(errs) != 0 {
+		message := &strings.Builder{}
+		_, _ = fmt.Fprint(message, `errors in generated Android.bp snapshot:
+
+Generated Android.bp contents
+========================================================================
+`)
+		for i, line := range strings.Split(contents, "\n") {
+			_, _ = fmt.Fprintf(message, "%6d:    %s\n", i+1, line)
+		}
+
+		_, _ = fmt.Fprint(message, `
+========================================================================
+
+Errors found:
+`)
+
+		for _, err := range errs {
+			_, _ = fmt.Fprintf(message, "%s\n", err.Error())
+		}
+
+		ctx.ModuleErrorf("%s", message.String())
+	}
+}
+
 func extractCommonProperties(ctx android.ModuleContext, extractor *commonValueExtractor, commonProperties interface{}, inputPropertiesSlice interface{}) {
 	err := extractor.extractCommonProperties(commonProperties, inputPropertiesSlice)
 	if err != nil {