String flag cannot be set to "-1"

[AkihiroSuda]

my urfave/cli version is

v1.22.1, v1.22.2, v1.22.3 (broken since v1.22.2)

Checklist

• Are you running the latest v1 release? The list of releases is here.
• Did you check the manual for your release? The v1 manual is here
• Did you perform a search about this problem? Here's the Github guide about searching.

Dependency Management

• My project is using go modules.
• My project is using vendoring.
• My project is automatically downloading the latest version.
• I am unsure of what my dependency management setup is.

Describe the bug

This flag can be set to "-1" on v1.22.1 but cannot be set since v1.22.2.

		cli.StringFlag{
			Name:  "memory-swap",
			Usage: "Total memory usage (memory + swap); set '-1' to enable unlimited swap",
		},

https://github.com/opencontainers/runc/blob/be51398a8af0b32b0b580e4da069cc6f704639bf/update.go#L111-L114

Regression in v1.22.1...v1.22.2

To reproduce

Specify urfave/cli version in go.mod in the runc tree, run go mod tidy, go mod vendor, and make integration.

Observed behavior

# runc update test_update --memory-swap -1 (status=1):
# Incorrect Usage: flag provided but not defined: -1

Expected behavior

It should not fail.

Additional context

opencontainers/runc#2268 (comment)

Run go version and paste its output here

For vendoring:

go version go1.14.1 linux/amd64

For running the containerized test suite:

go version go1.12.17 linux/amd64

[coilysiren]

😅 looks like it thinks -1 is a flag called 1. This bug makes sense, thanks for the well written issue @AkihiroSuda!

🙏 PRs are welcome 🙏

[thaJeztah]

Did some quick testing to do a minimal reproducer (LOL, I never worked with urfave/cli, so "code by example" 😅);

package main

import (
	"fmt"
	"os"
	"strings"

	"github.com/urfave/cli"
)

func main() {
	app := cli.NewApp()
	app.Name = "flagtest"

	app.Action = func(c *cli.Context) error {
		fmt.Println("opt:", c.String("opt"))
		fmt.Println("args:", strings.Join(c.Args(), ","))
		return nil
	}
	app.Commands = []cli.Command{{
		Name: "subcommand",
		Action: func(c *cli.Context) error {
			fmt.Println("opt:", c.String("opt"))
			fmt.Println("args:", strings.Join(c.Args(), ","))
			return nil
		},
		Flags: []cli.Flag{
			cli.StringFlag{
				Name:  "opt",
				Usage: "opt; set '-1' to disable",
			},
		},
	}}

	if err := app.Run(os.Args); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}

Testing variations;

go run flagtest.go subcommand
option:
args:

go run flagtest.go subcommand arg1
opt:
args: arg1

go run flagtest.go subcommand arg1 arg2
opt:
args: arg1,arg2

go run flagtest.go subcommand --opt opt-value
option: opt-value
args:

go run flagtest.go subcommand --opt opt-value arg1
opt: opt-value
args: arg1

go run flagtest.go subcommand --opt opt-value arg1 arg2
opt: opt-value
args: arg1,arg2

go run flagtest.go subcommand arg1 --opt opt-value
opt: opt-value
args: arg1

go run flagtest.go subcommand arg1 --opt opt-value arg2
opt: opt-value
args: arg1,arg2

Using -opt-value (leading hyphen (-));

go run flagtest.go subcommand --opt -opt-value
opt: -opt-value
args:

go run flagtest.go subcommand --opt -opt-value arg1
Incorrect Usage: flag provided but not defined: -opt-value


go run flagtest.go subcommand --opt -opt-value arg1 arg2
Incorrect Usage: flag provided but not defined: -opt-value

go run flagtest.go subcommand arg1 --opt -opt-value
Incorrect Usage: flag provided but not defined: -opt-value


go run flagtest.go subcommand arg1 --opt -opt-value arg2
opt: arg2
args: arg1,-opt-value

[thaJeztah]

And a test-case;

func TestParseAndRunHyphenValues(t *testing.T) {
	cases := []struct {
		testArgs     []string
		expectedArgs []string
		expectedOpt string
	}{
		{[]string{"foo", "test", "arg1"}, []string{"arg1"}, ""},
		{[]string{"foo", "test", "arg1", "arg2"}, []string{"arg1", "arg2"}, ""},
		{[]string{"foo", "test", "--opt", "opt-value"}, []string{}, "opt-value"},
		{[]string{"foo", "test", "--opt", "opt-value", "arg1"}, []string{"arg1"}, "opt-value"},
		{[]string{"foo", "test", "--opt", "opt-value", "arg1", "arg2"}, []string{"arg1", "arg2"}, "opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "opt-value"}, []string{"arg1"}, "opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "opt-value", "arg2"}, []string{"arg1", "arg2"}, "opt-value"},
		
		{[]string{"foo", "test", "--opt", "-opt-value"}, []string{}, "-opt-value"},
		{[]string{"foo", "test", "--opt", "-opt-value", "arg1"}, []string{"arg1"}, "-opt-value"},
		{[]string{"foo", "test", "--opt", "-opt-value", "arg1", "arg2"}, []string{"arg1", "arg2"}, "-opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "-opt-value"}, []string{"arg1"}, "-opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "-opt-value", "arg2"}, []string{"arg1", "arg2"}, "-opt-value"},
		
		{[]string{"foo", "test", "--opt", "--opt-value"}, []string{}, "--opt-value"},
		{[]string{"foo", "test", "--opt", "--opt-value", "arg1"}, []string{"arg1"}, "--opt-value"},
		{[]string{"foo", "test", "--opt", "--opt-value", "arg1", "arg2"}, []string{"arg1", "arg2"}, "--opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "--opt-value"}, []string{"arg1"}, "-opt-value"},
		{[]string{"foo", "test", "arg1", "--opt", "--opt-value", "arg2"}, []string{"arg1", "arg2"}, "--opt-value"},
	}

	for _, tc := range cases {
		tc := tc
		t.Run(strings.Join(tc.testArgs, "_"), func(t *testing.T){
			var (
				args []string
				opt string
			)

			cmd := Command{
				Name:        "test",
				Usage:       "this is for testing",
				Description: "testing",
				Action: func(c *Context) error {
					args = c.Args()
					opt = c.String("opt")
					return nil
				},
				Flags: []Flag{StringFlag{
					Name:  "opt",
					Usage: "opt; set '-1' to disable",
				}},
			}

			app := NewApp()
			app.Writer = ioutil.Discard
			app.ErrWriter = ioutil.Discard
			app.Commands = []Command{cmd}

			err := app.Run(tc.testArgs)

			expect(t, err, nil)
			expect(t, args, tc.expectedArgs)
			expect(t, opt, tc.expectedOpt)
		})

	}
}

(I'll open a "draft" PR with the test case)

[thaJeztah]

opened #1135 as a draft; I'll try to do a git-bisect and/or look at a fix, but not sure yet if I find time (thought the test-case would be a start to assist in this); anyone else: feel free to pick up the work if I don't come round to it