urfave / cli

My urfave/cli version is

v2.25.3

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Dependency Management

My project is using go modules.

Describe the bug

The value of .Count for a BoolFlag is impacted by the number of aliases defined for that flag.

To reproduce

Reproducible program:

package main

import (
	"fmt"
	"os"

	"github.com/urfave/cli/v2"
)

func main() {
	verbosity := 0
	
	app := &cli.App{
		Flags: []cli.Flag{
			&cli.BoolFlag{
				Name: "verbose",
				Aliases: []string{"v"},
				Count: &verbosity,
			},
		},
		Action: func(c *cli.Context) error {
			fmt.Printf("Running with verbosity: %d\n", verbosity)
			return nil
		},
	}

	app.Run(os.Args)
}

Observed behavior

$ go run main.go -v
Running with verbosity: 2

Expected behavior

I would expect the count to be incremented only once, i.e.:

$ go run main.go -v
Running with verbosity: 1

Additional context

Beyond the initial value, things are incremented as expected:

$ go run main.go -v -v
Running with verbosity: 3

Want to fix this yourself?

I'd be happy to, though I don't think I have enough context to implement a suitable solution. The trace is:

When we .Apply a BoolFlag we copy the count pointer for each alias

cli/flag_bool.go

Line 138 in dc77f3c

value := newBoolValue(f.Value, dest, count)
And when we .Set the flag we increment this count

cli/flag_bool.go

Line 38 in dc77f3c

*b.count = *b.count + 1

So when we run a command:

We parse the flags

cli/command.go

Line 158 in acbbbf2

set, err := c.parseFlags(&a, cCtx)
Which requires normalizing

cli/command.go

Line 384 in acbbbf2

if err := normalizeFlags(c.Flags, set); err != nil {
When normalizing we copy for each alias we didn't see

cli/flag.go

Line 229 in acbbbf2

copyFlag(name, ff, set)
Which in turn sets the value

cli/flag.go

Line 199 in acbbbf2

_ = set.Set(name, ff.Value.String())

Consequently the flag is .Set once per alias, so the count is incremented once per alias.

Maybe flag types could implement the copying logic themselves?

Run `go version` and paste its output here

$ go version
go version go1.20.4 linux/amd64

Run `go env` and paste its output here

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOENV="/home/user/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/user/.local/share/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/user/.local/share/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.4"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/user/src/cli/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3085526498=/tmp/go-build -gno-record-gcc-switches"

@matthewhughes934 Try this "fix"

`BoolFlag.Count` increment once per alias