Rename --build-tags to --load-build-tags and add 'ignore_autogenerated' as a default

Author: joelanford

cmd/controller-gen/main.go

@@ -195,7 +195,7 @@ func main() {
 	cmd.Flags().CountVarP(&whichLevel, "which-markers", "w", "print out all markers available with the requested generators\n(up to -www for the most detailed output, or -wwww for json output)")
 	cmd.Flags().CountVarP(&helpLevel, "detailed-help", "h", "print out more detailed help\n(up to -hhh for the most detailed output, or -hhhh for json output)")
 	cmd.Flags().BoolVar(&showVersion, "version", false, "show version")
-	cmd.Flags().StringSliceVar(&buildTags, "build-tags", nil, "build tags to use when loading Go packages")
+	cmd.Flags().StringSliceVar(&buildTags, "load-build-tags", []string{"ignore_autogenerated"}, "build tags to use when loading Go packages")
 	cmd.Flags().Bool("help", false, "print out usage and a summary of options")
 	oldUsage := cmd.UsageFunc()
 	cmd.SetUsageFunc(func(c *cobra.Command) error {

pkg/loader/loader.go

@@ -374,8 +374,14 @@ func LoadRootsWithConfig(cfg *packages.Config, roots ...string) ([]*Package, err
 	if l.cfg.Fset == nil {
 		l.cfg.Fset = token.NewFileSet()
 	}
-	// put our build flags first so that callers can override them
-	l.cfg.BuildFlags = append([]string{"-tags", "ignore_autogenerated"}, l.cfg.BuildFlags...)
+
+	// put our build flags first so that callers can override them.
+	//
+	// NOTE: if callers provide their own `-tags` flag, then our hardcoded `ignore_autogenerated` tag
+	//   will be ignored. Callers that provide custom tags MUST include `ignore_autogenerated` in their
+	//   custom tag set if they want that tag to remain active. Users can explicitly pass custom build
+	//   flags with `-tags=""` to disable use of the default `ignore_autogenerated` tag.
+	l.cfg.BuildFlags = append([]string{"-tags=ignore_autogenerated"}, l.cfg.BuildFlags...)
 
 	// Visit the import graphs of the loaded, root packages. If an imported
 	// package refers to another loaded, root package, then replace the