From c4d07f67e37a0a9e0dc48c6caf65d874af3b8862 Mon Sep 17 00:00:00 2001
From: Tibor Vass <tibor@docker.com>
Date: Thu, 30 Apr 2020 12:25:30 -0700
Subject: [PATCH] commands: check if flag is set instead of using
 flagutil.Tristate

Fixes --pull and --no-cache without argument

Signed-off-by: Tibor Vass <tibor@docker.com>
---
 commands/bake.go          |  8 ++++---
 commands/build.go         | 44 ++++++++++++++++++++++++++++++++-------
 util/flagutil/flagutil.go | 36 --------------------------------
 3 files changed, 41 insertions(+), 47 deletions(-)
 delete mode 100644 util/flagutil/flagutil.go

diff --git a/commands/bake.go b/commands/bake.go
index e25f088d..c64eefd6 100644
--- a/commands/bake.go
+++ b/commands/bake.go
@@ -106,13 +106,15 @@ func bakeCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 		Use:     "bake [OPTIONS] [TARGET...]",
 		Aliases: []string{"f"},
 		Short:   "Build from a file",
-		RunE: func(cmd *cobra.Command, args []string) error {
-			return runBake(dockerCli, args, options)
-		},
 	}
 
 	flags := cmd.Flags()
 
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		handleUnsetFlags(flags, &options)
+		return runBake(dockerCli, args, options)
+	}
+
 	flags.StringArrayVarP(&options.files, "file", "f", []string{}, "Build definition file")
 	flags.BoolVar(&options.printOnly, "print", false, "Print the options without building")
 	flags.StringArrayVar(&options.overrides, "set", nil, "Override target value (eg: targetpattern.key=value)")
diff --git a/commands/build.go b/commands/build.go
index ff9eb47d..5cdf251c 100644
--- a/commands/build.go
+++ b/commands/build.go
@@ -7,7 +7,6 @@ import (
 	"strings"
 
 	"github.com/docker/buildx/build"
-	"github.com/docker/buildx/util/flagutil"
 	"github.com/docker/buildx/util/platformutil"
 	"github.com/docker/buildx/util/progress"
 	"github.com/docker/cli/cli"
@@ -71,6 +70,18 @@ type commonOptions struct {
 	exportLoad bool
 }
 
+func (o *commonOptions) Unset(s string) error {
+	switch s {
+	case "pull":
+		o.noCache = nil
+	case "no-cache":
+		o.pull = nil
+	default:
+		return errors.Errorf("cannot unset flag %q", s)
+	}
+	return nil
+}
+
 func runBuild(dockerCli command.Cli, in buildOptions) error {
 	if in.squash {
 		return errors.Errorf("squash currently not implemented")
@@ -209,6 +220,21 @@ func buildTargets(ctx context.Context, dockerCli command.Cli, opts map[string]bu
 	return err
 }
 
+type unsetter interface {
+	Unset(flagName string) error
+}
+
+func handleUnsetFlags(flags *pflag.FlagSet, options unsetter) error {
+	for _, name := range []string{"pull", "no-cache"} {
+		if !flags.Lookup(name).Changed {
+			if err := options.Unset(name); err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}
+
 func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 	var options buildOptions
 
@@ -217,15 +243,17 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 		Aliases: []string{"b"},
 		Short:   "Start a build",
 		Args:    cli.ExactArgs(1),
-		RunE: func(cmd *cobra.Command, args []string) error {
-			options.contextPath = args[0]
-			options.builder = rootOpts.builder
-			return runBuild(dockerCli, options)
-		},
 	}
 
 	flags := cmd.Flags()
 
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		options.contextPath = args[0]
+		options.builder = rootOpts.builder
+		handleUnsetFlags(flags, &options)
+		return runBuild(dockerCli, options)
+	}
+
 	flags.BoolVar(&options.exportPush, "push", false, "Shorthand for --output=type=registry")
 	flags.BoolVar(&options.exportLoad, "load", false, "Shorthand for --output=type=docker")
 
@@ -305,9 +333,9 @@ func buildCmd(dockerCli command.Cli, rootOpts *rootOptions) *cobra.Command {
 }
 
 func commonBuildFlags(options *commonOptions, flags *pflag.FlagSet) {
-	flags.Var(flagutil.Tristate(options.noCache), "no-cache", "Do not use cache when building the image")
+	options.noCache = flags.Bool("no-cache", false, "Do not use cache when building the image")
 	flags.StringVar(&options.progress, "progress", "auto", "Set type of progress output (auto, plain, tty). Use plain to show container output")
-	flags.Var(flagutil.Tristate(options.pull), "pull", "Always attempt to pull a newer version of the image")
+	options.pull = flags.Bool("pull", false, "Always attempt to pull a newer version of the image")
 }
 
 func listToMap(values []string, defaultEnv bool) map[string]string {
diff --git a/util/flagutil/flagutil.go b/util/flagutil/flagutil.go
deleted file mode 100644
index f1f9c9b7..00000000
--- a/util/flagutil/flagutil.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package flagutil
-
-import "strconv"
-
-type tristate struct {
-	opt *bool
-}
-
-// Tristate is a tri-state boolean flag type.
-// It can be set, but not unset.
-func Tristate(opt *bool) tristate {
-	return tristate{opt}
-}
-
-func (t tristate) Type() string {
-	return "tristate"
-}
-
-func (t tristate) String() string {
-	if t.opt == nil {
-		return "(unset)"
-	}
-	if *t.opt {
-		return "true"
-	}
-	return "false"
-}
-
-func (t tristate) Set(s string) error {
-	b, err := strconv.ParseBool(s)
-	if err != nil {
-		return err
-	}
-	t.opt = &b
-	return nil
-}