Automerge supports deleting branch automatically after merging (#32343)

Resolve #32341 
~Depends on #27151~

- [x] It will display a checkbox of deleting the head branch on the pull
request view page when starting an auto-merge task.
- [x] Add permission check before deleting the branch
- [x] Add delete branch comment for those closing pull requests because
of head branch or base branch was deleted.
- [x] Merge `RetargetChildrenOnMerge` and `AddDeletePRBranchComment`
into `service.DeleteBranch`.

Author: lunny

models/issues/pull_list.go

@@ -166,6 +166,23 @@ func (prs PullRequestList) getRepositoryIDs() []int64 {
 	return repoIDs.Values()
 }
 
+func (prs PullRequestList) SetBaseRepo(baseRepo *repo_model.Repository) {
+	for _, pr := range prs {
+		if pr.BaseRepo == nil {
+			pr.BaseRepo = baseRepo
+		}
+	}
+}
+
+func (prs PullRequestList) SetHeadRepo(headRepo *repo_model.Repository) {
+	for _, pr := range prs {
+		if pr.HeadRepo == nil {
+			pr.HeadRepo = headRepo
+			pr.isHeadRepoLoaded = true
+		}
+	}
+}
+
 func (prs PullRequestList) LoadRepositories(ctx context.Context) error {
 	repoIDs := prs.getRepositoryIDs()
 	reposMap := make(map[int64]*repo_model.Repository, len(repoIDs))

models/migrations/migrations.go

@@ -22,6 +22,7 @@ import (
 	"code.gitea.io/gitea/models/migrations/v1_21"
 	"code.gitea.io/gitea/models/migrations/v1_22"
 	"code.gitea.io/gitea/models/migrations/v1_23"
+	"code.gitea.io/gitea/models/migrations/v1_24"
 	"code.gitea.io/gitea/models/migrations/v1_6"
 	"code.gitea.io/gitea/models/migrations/v1_7"
 	"code.gitea.io/gitea/models/migrations/v1_8"
@@ -369,6 +370,9 @@ func prepareMigrationTasks() []*migration {
 		newMigration(309, "Improve Notification table indices", v1_23.ImproveNotificationTableIndices),
 		newMigration(310, "Add Priority to ProtectedBranch", v1_23.AddPriorityToProtectedBranch),
 		newMigration(311, "Add TimeEstimate to Issue table", v1_23.AddTimeEstimateColumnToIssueTable),
+
+		// Gitea 1.23.0-rc0 ends at migration ID number 311 (database version 312)
+		newMigration(312, "Add DeleteBranchAfterMerge to AutoMerge", v1_24.AddDeleteBranchAfterMergeForAutoMerge),
 	}
 	return preparedMigrations
 }

models/migrations/v1_24/v312.go

@@ -0,0 +1,21 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_24 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+type pullAutoMerge struct {
+	DeleteBranchAfterMerge bool
+}
+
+// TableName return database table name for xorm
+func (pullAutoMerge) TableName() string {
+	return "pull_auto_merge"
+}
+
+func AddDeleteBranchAfterMergeForAutoMerge(x *xorm.Engine) error {
+	return x.Sync(new(pullAutoMerge))
+}

models/pull/automerge.go

@@ -15,13 +15,14 @@ import (
 
 // AutoMerge represents a pull request scheduled for merging when checks succeed
 type AutoMerge struct {
-	ID          int64                 `xorm:"pk autoincr"`
-	PullID      int64                 `xorm:"UNIQUE"`
-	DoerID      int64                 `xorm:"INDEX NOT NULL"`
-	Doer        *user_model.User      `xorm:"-"`
-	MergeStyle  repo_model.MergeStyle `xorm:"varchar(30)"`
-	Message     string                `xorm:"LONGTEXT"`
-	CreatedUnix timeutil.TimeStamp    `xorm:"created"`
+	ID                     int64                 `xorm:"pk autoincr"`
+	PullID                 int64                 `xorm:"UNIQUE"`
+	DoerID                 int64                 `xorm:"INDEX NOT NULL"`
+	Doer                   *user_model.User      `xorm:"-"`
+	MergeStyle             repo_model.MergeStyle `xorm:"varchar(30)"`
+	Message                string                `xorm:"LONGTEXT"`
+	DeleteBranchAfterMerge bool
+	CreatedUnix            timeutil.TimeStamp `xorm:"created"`
 }
 
 // TableName return database table name for xorm
@@ -49,7 +50,7 @@ func IsErrAlreadyScheduledToAutoMerge(err error) bool {
 }
 
 // ScheduleAutoMerge schedules a pull request to be merged when all checks succeed
-func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pullID int64, style repo_model.MergeStyle, message string) error {
+func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pullID int64, style repo_model.MergeStyle, message string, deleteBranchAfterMerge bool) error {
 	// Check if we already have a merge scheduled for that pull request
 	if exists, _, err := GetScheduledMergeByPullID(ctx, pullID); err != nil {
 		return err
@@ -58,10 +59,11 @@ func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pullID int64,
 	}
 
 	_, err := db.GetEngine(ctx).Insert(&AutoMerge{
-		DoerID:     doer.ID,
-		PullID:     pullID,
-		MergeStyle: style,
-		Message:    message,
+		DoerID:                 doer.ID,
+		PullID:                 pullID,
+		MergeStyle:             style,
+		Message:                message,
+		DeleteBranchAfterMerge: deleteBranchAfterMerge,
 	})
 	return err
 }

routers/api/v1/repo/branch.go

@@ -150,7 +150,7 @@ func DeleteBranch(ctx *context.APIContext) {
 		}
 	}
 
-	if err := repo_service.DeleteBranch(ctx, ctx.Doer, ctx.Repo.Repository, ctx.Repo.GitRepo, branchName); err != nil {
+	if err := repo_service.DeleteBranch(ctx, ctx.Doer, ctx.Repo.Repository, ctx.Repo.GitRepo, branchName, nil); err != nil {
 		switch {
 		case git.IsErrBranchNotExist(err):
 			ctx.NotFound(err)

routers/api/v1/repo/pull.go

@@ -971,7 +971,7 @@ func MergePullRequest(ctx *context.APIContext) {
 	}
 
 	if form.MergeWhenChecksSucceed {
-		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message)
+		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message, form.DeleteBranchAfterMerge)
 		if err != nil {
 			if pull_model.IsErrAlreadyScheduledToAutoMerge(err) {
 				ctx.Error(http.StatusConflict, "ScheduleAutoMerge", err)
@@ -1043,11 +1043,8 @@ func MergePullRequest(ctx *context.APIContext) {
 				}
 				defer headRepo.Close()
 			}
-			if err := pull_service.RetargetChildrenOnMerge(ctx, ctx.Doer, pr); err != nil {
-				ctx.Error(http.StatusInternalServerError, "RetargetChildrenOnMerge", err)
-				return
-			}
-			if err := repo_service.DeleteBranch(ctx, ctx.Doer, pr.HeadRepo, headRepo, pr.HeadBranch); err != nil {
+
+			if err := repo_service.DeleteBranch(ctx, ctx.Doer, pr.HeadRepo, headRepo, pr.HeadBranch, pr); err != nil {
 				switch {
 				case git.IsErrBranchNotExist(err):
 					ctx.NotFound(err)
@@ -1060,10 +1057,6 @@ func MergePullRequest(ctx *context.APIContext) {
 				}
 				return
 			}
-			if err := issues_model.AddDeletePRBranchComment(ctx, ctx.Doer, pr.BaseRepo, pr.Issue.ID, pr.HeadBranch); err != nil {
-				// Do not fail here as branch has already been deleted
-				log.Error("DeleteBranch: %v", err)
-			}
 		}
 	}
 

routers/private/hook_post_receive_test.go

@@ -27,7 +27,7 @@ func TestHandlePullRequestMerging(t *testing.T) {
 
 	user1 := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: 1})
 
-	err = pull_model.ScheduleAutoMerge(db.DefaultContext, user1, pr.ID, repo_model.MergeStyleSquash, "squash merge a pr")
+	err = pull_model.ScheduleAutoMerge(db.DefaultContext, user1, pr.ID, repo_model.MergeStyleSquash, "squash merge a pr", false)
 	assert.NoError(t, err)
 
 	autoMerge := unittest.AssertExistsAndLoadBean(t, &pull_model.AutoMerge{PullID: pr.ID})

routers/web/repo/branch.go

@@ -97,7 +97,7 @@ func DeleteBranchPost(ctx *context.Context) {
 	defer redirect(ctx)
 	branchName := ctx.FormString("name")
 
-	if err := repo_service.DeleteBranch(ctx, ctx.Doer, ctx.Repo.Repository, ctx.Repo.GitRepo, branchName); err != nil {
+	if err := repo_service.DeleteBranch(ctx, ctx.Doer, ctx.Repo.Repository, ctx.Repo.GitRepo, branchName, nil); err != nil {
 		switch {
 		case git.IsErrBranchNotExist(err):
 			log.Debug("DeleteBranch: Can't delete non existing branch '%s'", branchName)

routers/web/repo/pull.go

@@ -1097,7 +1097,7 @@ func MergePullRequest(ctx *context.Context) {
 		// delete all scheduled auto merges
 		_ = pull_model.DeleteScheduledAutoMerge(ctx, pr.ID)
 		// schedule auto merge
-		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message)
+		scheduled, err := automerge.ScheduleAutoMerge(ctx, ctx.Doer, pr, repo_model.MergeStyle(form.Do), message, form.DeleteBranchAfterMerge)
 		if err != nil {
 			ctx.ServerError("ScheduleAutoMerge", err)
 			return
@@ -1504,12 +1504,7 @@ func CleanUpPullRequest(ctx *context.Context) {
 func deleteBranch(ctx *context.Context, pr *issues_model.PullRequest, gitRepo *git.Repository) {
 	fullBranchName := pr.HeadRepo.FullName() + ":" + pr.HeadBranch
 
-	if err := pull_service.RetargetChildrenOnMerge(ctx, ctx.Doer, pr); err != nil {
-		ctx.Flash.Error(ctx.Tr("repo.branch.deletion_failed", fullBranchName))
-		return
-	}
-
-	if err := repo_service.DeleteBranch(ctx, ctx.Doer, pr.HeadRepo, gitRepo, pr.HeadBranch); err != nil {
+	if err := repo_service.DeleteBranch(ctx, ctx.Doer, pr.HeadRepo, gitRepo, pr.HeadBranch, pr); err != nil {
 		switch {
 		case git.IsErrBranchNotExist(err):
 			ctx.Flash.Error(ctx.Tr("repo.branch.deletion_failed", fullBranchName))
@@ -1524,11 +1519,6 @@ func deleteBranch(ctx *context.Context, pr *issues_model.PullRequest, gitRepo *g
 		return
 	}
 
-	if err := issues_model.AddDeletePRBranchComment(ctx, ctx.Doer, pr.BaseRepo, pr.IssueID, pr.HeadBranch); err != nil {
-		// Do not fail here as branch has already been deleted
-		log.Error("DeleteBranch: %v", err)
-	}
-
 	ctx.Flash.Success(ctx.Tr("repo.branch.deletion_success", fullBranchName))
 }
 

services/automerge/automerge.go

@@ -24,6 +24,7 @@ import (
 	"code.gitea.io/gitea/modules/queue"
 	notify_service "code.gitea.io/gitea/services/notify"
 	pull_service "code.gitea.io/gitea/services/pull"
+	repo_service "code.gitea.io/gitea/services/repository"
 )
 
 // prAutoMergeQueue represents a queue to handle update pull request tests
@@ -63,9 +64,9 @@ func addToQueue(pr *issues_model.PullRequest, sha string) {
 }
 
 // ScheduleAutoMerge if schedule is false and no error, pull can be merged directly
-func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pull *issues_model.PullRequest, style repo_model.MergeStyle, message string) (scheduled bool, err error) {
+func ScheduleAutoMerge(ctx context.Context, doer *user_model.User, pull *issues_model.PullRequest, style repo_model.MergeStyle, message string, deleteBranchAfterMerge bool) (scheduled bool, err error) {
 	err = db.WithTx(ctx, func(ctx context.Context) error {
-		if err := pull_model.ScheduleAutoMerge(ctx, doer, pull.ID, style, message); err != nil {
+		if err := pull_model.ScheduleAutoMerge(ctx, doer, pull.ID, style, message, deleteBranchAfterMerge); err != nil {
 			return err
 		}
 		scheduled = true
@@ -303,4 +304,10 @@ func handlePullRequestAutoMerge(pullID int64, sha string) {
 		// on the pull request page. But this should not be finished in a bug fix PR which will be backport to release branch.
 		return
 	}
+
+	if pr.Flow == issues_model.PullRequestFlowGithub && scheduledPRM.DeleteBranchAfterMerge {
+		if err := repo_service.DeleteBranch(ctx, doer, pr.HeadRepo, headGitRepo, pr.HeadBranch, pr); err != nil {
+			log.Error("DeletePullRequestHeadBranch: %v", err)
+		}
+	}
 }