CountVar doesn't support default value setting

[ZhouXing19]

When setting a count flag, the default value setting is not supported -- FlagSet.CountVarP() or FlagSet.CountVar() only takes name and usage as parameters. Weirdly, it is noted in the comment that default value is allowed.

pflag/count.go

Lines 47 to 58 in d5e0c06

	// CountVar defines a count flag with specified name, default value, and usage string.
	// The argument p points to an int variable in which to store the value of the flag.
	// A count flag will add 1 to its value every time it is found on the command line
	func (f *FlagSet) CountVar(p *int, name string, usage string) {
	f.CountVarP(p, name, "", usage)
	}
	// CountVarP is like CountVar only take a shorthand for the flag name.
	func (f *FlagSet) CountVarP(p *int, name, shorthand string, usage string) {
	flag := f.VarPF(newCountValue(0, p), name, shorthand, usage)
	flag.NoOptDefVal = "+1"
	}

[fredbi]

IMHO, the only way to preserve a backard compatibility would be to extend these methods with some ...Option parameter. One such option could support adding a default value.