commands: add an alias for --check to be the same as --call=check

This adds an alias for `--check` that causes it to behave the same as
`--call=check`. This is done using `BoolFunc` to call a function when
the option is seen and to set it to the correct value. This should allow
command line flags like `--check --call=targets` to work correctly (even
though they conflict) by making it so the first invocation sets the
print function to `check` and the second overwrites the first. This is
the expected behavior for these types of boolean flags.

`BoolFunc` itself is part of the standard library flags package, but
never seems to have made it into pflag possibly because it was added in
go 1.21.

https://pkg.go.dev/flag#FlagSet.BoolFunc

Signed-off-by: Jonathan A. Sternberg <jonathan.sternberg@docker.com>

commands/build.go

@@ -629,6 +629,8 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions, debugConfig *debug.D
 	}
 
 	flags.StringVar(&options.printFunc, "call", "build", `Set method for evaluating build ("check", "outline", "targets")`)
+	flags.VarPF(callAlias(options, "check"), "check", "", `Shorthand for "--call=check"`)
+	flags.Lookup("check").NoOptDefVal = "true"
 
 	// hidden flags
 	var ignore string
@@ -1003,6 +1005,20 @@ func maybeJSONArray(v string) []string {
 	return []string{v}
 }
 
+func callAlias(options *buildOptions, value string) cobrautil.BoolFuncValue {
+	return func(s string) error {
+		v, err := strconv.ParseBool(s)
+		if err != nil {
+			return err
+		}
+
+		if v {
+			options.printFunc = value
+		}
+		return nil
+	}
+}
+
 // timeBuildCommand will start a timer for timing the build command. It records the time when the returned
 // function is invoked into a metric.
 func timeBuildCommand(mp metric.MeterProvider, attrs attribute.Set) func(err error) {