Auto-forward main branches after fetching (#4493)

- **PR Description**

Add a new user config for auto-forwarding branches after fetching; by
default this is set to "onlyMainBranches", but it can be set to
"allBranches" to extend it to feature branches too, or to "none" to
disable it.

This is used both when fetching manually by pressing `f` in the files
panel, and for automatic background fetching.

Author: stefanhaller

docs/Config.md

@@ -337,6 +337,10 @@ git:
   # If true, periodically refresh files and submodules
   autoRefresh: true
 
+  # If not "none", lazygit will automatically forward branches to their upstream after fetching. Applies to branches that are not the currently checked out branch, and only to those that are strictly behind their upstream (as opposed to diverged).
+  # Possible values: 'none' | 'onlyMainBranches' | 'allBranches'
+  autoForwardBranches: onlyMainBranches
+
   # If true, pass the --all arg to git fetch
   fetchAll: true
 

pkg/commands/git_commands/branch.go

@@ -285,3 +285,11 @@ func (self *BranchCommands) IsBranchMerged(branch *models.Branch, mainBranches *
 
 	return stdout == "", nil
 }
+
+func (self *BranchCommands) UpdateBranchRefs(updateCommands string) error {
+	cmdArgs := NewGitCmd("update-ref").
+		Arg("--stdin").
+		ToArgv()
+
+	return self.cmd.New(cmdArgs).SetStdin(updateCommands).Run()
+}

pkg/commands/oscommands/cmd_obj.go

@@ -21,6 +21,9 @@ type ICmdObj interface {
 	// outputs args vector e.g. ["git", "commit", "-m", "my message"]
 	Args() []string
 
+	// Set a string to be used as stdin for the command.
+	SetStdin(input string) ICmdObj
+
 	AddEnvVars(...string) ICmdObj
 	GetEnvVars() []string
 
@@ -131,6 +134,12 @@ func (self *CmdObj) Args() []string {
 	return self.cmd.Args
 }
 
+func (self *CmdObj) SetStdin(input string) ICmdObj {
+	self.cmd.Stdin = strings.NewReader(input)
+
+	return self
+}
+
 func (self *CmdObj) AddEnvVars(vars ...string) ICmdObj {
 	self.cmd.Env = append(self.cmd.Env, vars...)
 

pkg/config/user_config.go

@@ -244,6 +244,9 @@ type GitConfig struct {
 	AutoFetch bool `yaml:"autoFetch"`
 	// If true, periodically refresh files and submodules
 	AutoRefresh bool `yaml:"autoRefresh"`
+	// If not "none", lazygit will automatically forward branches to their upstream after fetching. Applies to branches that are not the currently checked out branch, and only to those that are strictly behind their upstream (as opposed to diverged).
+	// Possible values: 'none' | 'onlyMainBranches' | 'allBranches'
+	AutoForwardBranches string `yaml:"autoForwardBranches" jsonschema:"enum=none,enum=onlyMainBranches,enum=allBranches"`
 	// If true, pass the --all arg to git fetch
 	FetchAll bool `yaml:"fetchAll"`
 	// If true, lazygit will automatically stage files that used to have merge
@@ -822,6 +825,7 @@ func GetDefaultConfig() *UserConfig {
 			MainBranches:                 []string{"master", "main"},
 			AutoFetch:                    true,
 			AutoRefresh:                  true,
+			AutoForwardBranches:          "onlyMainBranches",
 			FetchAll:                     true,
 			AutoStageResolvedConflicts:   true,
 			BranchLogCmd:                 "git log --graph --color=always --abbrev-commit --decorate --date=relative --pretty=medium {{branchName}} --",

pkg/config/user_config_validation.go

@@ -19,6 +19,10 @@ func (config *UserConfig) Validate() error {
 		[]string{"none", "onlyArrow", "arrowAndNumber"}); err != nil {
 		return err
 	}
+	if err := validateEnum("git.autoForwardBranches", config.Git.AutoForwardBranches,
+		[]string{"none", "onlyMainBranches", "allBranches"}); err != nil {
+		return err
+	}
 	if err := validateKeybindings(config.Keybinding); err != nil {
 		return err
 	}

pkg/gui/background.go

@@ -125,7 +125,11 @@ func (self *BackgroundRoutineMgr) goEvery(interval time.Duration, stop chan stru
 func (self *BackgroundRoutineMgr) backgroundFetch() (err error) {
 	err = self.gui.git.Sync.FetchBackground()
 
-	_ = self.gui.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.BRANCHES, types.COMMITS, types.REMOTES, types.TAGS}, Mode: types.ASYNC})
+	_ = self.gui.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.BRANCHES, types.COMMITS, types.REMOTES, types.TAGS}, Mode: types.SYNC})
+
+	if err == nil {
+		err = self.gui.helpers.BranchesHelper.AutoForwardBranches()
+	}
 
 	return err
 }

pkg/gui/controllers/files_controller.go

@@ -1189,24 +1189,21 @@ func (self *FilesController) onClickMain(opts gocui.ViewMouseBindingOpts) error
 
 func (self *FilesController) fetch() error {
 	return self.c.WithWaitingStatus(self.c.Tr.FetchingStatus, func(task gocui.Task) error {
-		if err := self.fetchAux(task); err != nil {
-			return err
+		self.c.LogAction("Fetch")
+		err := self.c.Git().Sync.Fetch(task)
+
+		if err != nil && strings.Contains(err.Error(), "exit status 128") {
+			return errors.New(self.c.Tr.PassUnameWrong)
 		}
-		return self.c.Refresh(types.RefreshOptions{Mode: types.ASYNC})
-	})
-}
 
-func (self *FilesController) fetchAux(task gocui.Task) (err error) {
-	self.c.LogAction("Fetch")
-	err = self.c.Git().Sync.Fetch(task)
+		_ = self.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.BRANCHES, types.COMMITS, types.REMOTES, types.TAGS}, Mode: types.SYNC})
 
-	if err != nil && strings.Contains(err.Error(), "exit status 128") {
-		return errors.New(self.c.Tr.PassUnameWrong)
-	}
-
-	_ = self.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.BRANCHES, types.COMMITS, types.REMOTES, types.TAGS}, Mode: types.ASYNC})
+		if err == nil {
+			err = self.c.Helpers().BranchesHelper.AutoForwardBranches()
+		}
 
-	return err
+		return err
+	})
 }
 
 // Couldn't think of a better term than 'normalised'. Alas.

pkg/gui/controllers/helpers/branches_helper.go

@@ -2,6 +2,7 @@ package helpers
 
 import (
 	"errors"
+	"fmt"
 	"strings"
 
 	"github.com/jesseduffield/gocui"
@@ -263,3 +264,34 @@ func (self *BranchesHelper) deleteRemoteBranches(remoteBranches []*models.Remote
 	}
 	return nil
 }
+
+func (self *BranchesHelper) AutoForwardBranches() error {
+	if self.c.UserConfig().Git.AutoForwardBranches == "none" {
+		return nil
+	}
+
+	allBranches := self.c.UserConfig().Git.AutoForwardBranches == "allBranches"
+	branches := self.c.Model().Branches
+	updateCommands := ""
+	// The first branch is the currently checked out branch; skip it
+	for _, branch := range branches[1:] {
+		if branch.RemoteBranchStoredLocally() && (allBranches || lo.Contains(self.c.UserConfig().Git.MainBranches, branch.Name)) {
+			isStrictlyBehind := branch.IsBehindForPull() && !branch.IsAheadForPull()
+			if isStrictlyBehind {
+				updateCommands += fmt.Sprintf("update %s %s %s\n", branch.FullRefName(), branch.FullUpstreamRefName(), branch.CommitHash)
+			}
+		}
+	}
+
+	if updateCommands == "" {
+		return nil
+	}
+
+	self.c.LogAction(self.c.Tr.Actions.AutoForwardBranches)
+	self.c.LogCommand(strings.TrimRight(updateCommands, "\n"), false)
+	err := self.c.Git().Branch.UpdateBranchRefs(updateCommands)
+
+	_ = self.c.Refresh(types.RefreshOptions{Scope: []types.RefreshableView{types.BRANCHES}, Mode: types.SYNC})
+
+	return err
+}

pkg/i18n/english.go

@@ -931,6 +931,7 @@ type Actions struct {
 	RenameBranch                      string
 	CreateBranch                      string
 	FastForwardBranch                 string
+	AutoForwardBranches               string
 	CherryPick                        string
 	CheckoutFile                      string
 	DiscardOldFileChange              string
@@ -2059,6 +2060,7 @@ func EnglishTranslationSet() *TranslationSet {
 			MixedReset:                      "Mixed reset",
 			HardReset:                       "Hard reset",
 			FastForwardBranch:               "Fast forward branch",
+			AutoForwardBranches:             "Auto-forward branches",
 			Undo:                            "Undo",
 			Redo:                            "Redo",
 			CopyPullRequestURL:              "Copy pull request URL",
@@ -2137,6 +2139,12 @@ gui:
 			"0.44.0": `- The gui.branchColors config option is deprecated; it will be removed in a future version. Please use gui.branchColorPatterns instead.
 - The automatic coloring of branches starting with "feature/", "bugfix/", or "hotfix/" has been removed; if you want this, it's easy to set up using the new gui.branchColorPatterns option.`,
 			"0.49.0": `- Executing shell commands (with the ':' prompt) no longer uses an interactive shell, which means that if you want to use your shell aliases in this prompt, you need to do a little bit of setup work. See https://github.com/jesseduffield/lazygit/blob/master/docs/Config.md#using-aliases-or-functions-in-shell-commands for details.`,
+			"0.50.0": `- After fetching, main branches now get auto-forwarded to their upstream if they fall behind. This is useful for keeping your main or master branch up to date automatically. If you don't want this, you can disable it by setting the following in your config:
+
+git:
+  autoForwardBranches: none
+
+If, on the other hand, you want this even for feature branches, you can set it to 'allBranches' instead.`,
 		},
 	}
 }

pkg/integration/tests/sync/fetch_and_auto_forward_branches_all_branches.go

@@ -0,0 +1,54 @@
+package sync
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var FetchAndAutoForwardBranchesAllBranches = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Fetch from remote and auto-forward branches with config set to 'allBranches'",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig: func(config *config.AppConfig) {
+		config.GetUserConfig().Git.AutoForwardBranches = "allBranches"
+	},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateNCommits(3)
+		shell.NewBranch("feature")
+		shell.NewBranch("diverged")
+		shell.CloneIntoRemote("origin")
+		shell.SetBranchUpstream("master", "origin/master")
+		shell.SetBranchUpstream("feature", "origin/feature")
+		shell.SetBranchUpstream("diverged", "origin/diverged")
+		shell.Checkout("master")
+		shell.HardReset("HEAD^")
+		shell.Checkout("feature")
+		shell.HardReset("HEAD~2")
+		shell.Checkout("diverged")
+		shell.HardReset("HEAD~2")
+		shell.EmptyCommit("local")
+		shell.NewBranch("checked-out")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ↓2").DoesNotContain("↑"),
+				Contains("master ↓1").DoesNotContain("↑"),
+			)
+
+		t.Views().Files().
+			IsFocused().
+			Press(keys.Files.Fetch)
+
+		// AutoForwardBranches is "allBranches": both master and feature get forwarded
+		t.Views().Branches().
+			Lines(
+				Contains("checked-out").IsSelected(),
+				Contains("diverged ↓2↑1"),
+				Contains("feature ✓"),
+				Contains("master ✓"),
+			)
+	},
+})