internal/pkg/cli/flags.go

// Copyright 2026 Google LLC
//
// 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 cli provides utilities for building robust command-line interfaces.
package cli

import "flag"

// NewFlagSet creates a private FlagSet with ContinueOnError and inherits
// all flags currently registered in the global flag.CommandLine (e.g. glog flags).
// This prevents silent os.Exit(2) crashes and allows for explicit error handling
// in CI/CQ environments.
func NewFlagSet(name string) *flag.FlagSet {
	fs := flag.NewFlagSet(name, flag.ContinueOnError)

	// Copy flags from the global FlagSet to our private FlagSet.
	// This ensures that system-wide flags like -log_dir or -v (from glog)
	// continue to work correctly in the isolated set.
	flag.CommandLine.VisitAll(func(f *flag.Flag) {
		fs.Var(f.Value, f.Name, f.Usage)
	})

	return fs
}