Add "Update Branch" button to Pull Requests (#9784)

* add Divergence

* add Update Button

* first working version

* re-use code

* split raw merge commands and db-change functions (notify, cache, ...)

* use rawMerge (remove redundant code)

* own function to get Diverging of PRs

* use FlashError

* correct Error Msg

* hook is triggerd ... so remove comment

* add "branch2" to "user2/repo1" because it unit-test "TestPullView_ReviewerMissed" use it but dont exist jet :/

* move GetPerm to IsUserAllowedToUpdate

* add Flash Success MSG

* imprufe code
- remove useless js chage

* fix-lint

* TEST: add PullRequest ID:5
Repo: user2/repo1
Base: branch1
Head: pr-to-update

* correct comments

* make PR5 outdated

* fix Tests

* WIP: add pull update test

* update revs

* update locales

* working TEST

* update UI

* misspell

* change style

* add 1s delay so rev exist

* move row up (before merge row)

* fix lint nit

* UI remove divider

* Update style

* nits

* do it right

* introduce IsSameRepo

* remove useless check

Co-authored-by: Lauris BH <lauris@nix.lv>

integrations/api_issue_test.go

@@ -134,7 +134,7 @@ func TestAPISearchIssue(t *testing.T) {
 	var apiIssues []*api.Issue
 	DecodeJSON(t, resp, &apiIssues)
 
-	assert.Len(t, apiIssues, 8)
+	assert.Len(t, apiIssues, 9)
 
 	query := url.Values{}
 	query.Add("token", token)
@@ -142,7 +142,7 @@ func TestAPISearchIssue(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 8)
+	assert.Len(t, apiIssues, 9)
 
 	query.Add("state", "closed")
 	link.RawQuery = query.Encode()
@@ -163,5 +163,5 @@ func TestAPISearchIssue(t *testing.T) {
 	req = NewRequest(t, "GET", link.String())
 	resp = session.MakeRequest(t, req, http.StatusOK)
 	DecodeJSON(t, resp, &apiIssues)
-	assert.Len(t, apiIssues, 0)
+	assert.Len(t, apiIssues, 1)
 }

integrations/gitea-repositories-meta/user2/repo1.git/info/refs

@@ -1 +1,3 @@
 65f1bf27bc3bf70f64657658635e66094edbcb4d	refs/heads/master
+985f0301dba5e7b34be866819cd15ad3d8f508ee	refs/heads/branch2
+62fb502a7172d4453f0322a2cc85bddffa57f07a	refs/heads/pr-to-update

integrations/gitea-repositories-meta/user2/repo1.git/refs/heads/branch2

@@ -0,0 +1 @@
+985f0301dba5e7b34be866819cd15ad3d8f508ee

integrations/gitea-repositories-meta/user2/repo1.git/refs/heads/pr-to-update

@@ -0,0 +1 @@
+62fb502a7172d4453f0322a2cc85bddffa57f07a

integrations/gitea-repositories-meta/user2/repo1.git/refs/pull/2/head

@@ -0,0 +1 @@
+4a357436d925b5c974181ff12a994538ddc5a269

integrations/gitea-repositories-meta/user2/repo1.git/refs/pull/5/head

@@ -0,0 +1 @@
+62fb502a7172d4453f0322a2cc85bddffa57f07a

integrations/pull_update_test.go

@@ -0,0 +1,136 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package integrations
+
+import (
+	"fmt"
+	"net/url"
+	"testing"
+	"time"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/repofiles"
+	repo_module "code.gitea.io/gitea/modules/repository"
+	pull_service "code.gitea.io/gitea/services/pull"
+	repo_service "code.gitea.io/gitea/services/repository"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestPullUpdate(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, giteaURL *url.URL) {
+		//Create PR to test
+		user := models.AssertExistsAndLoadBean(t, &models.User{ID: 2}).(*models.User)
+		org26 := models.AssertExistsAndLoadBean(t, &models.User{ID: 26}).(*models.User)
+		pr := createOutdatedPR(t, user, org26)
+
+		//Test GetDiverging
+		diffCount, err := pull_service.GetDiverging(pr)
+		assert.NoError(t, err)
+		assert.EqualValues(t, 1, diffCount.Behind)
+		assert.EqualValues(t, 1, diffCount.Ahead)
+
+		message := fmt.Sprintf("Merge branch '%s' into %s", pr.BaseBranch, pr.HeadBranch)
+		err = pull_service.Update(pr, user, message)
+		assert.NoError(t, err)
+
+		//Test GetDiverging after update
+		diffCount, err = pull_service.GetDiverging(pr)
+		assert.NoError(t, err)
+		assert.EqualValues(t, 0, diffCount.Behind)
+		assert.EqualValues(t, 2, diffCount.Ahead)
+
+	})
+}
+
+func createOutdatedPR(t *testing.T, actor, forkOrg *models.User) *models.PullRequest {
+	baseRepo, err := repo_service.CreateRepository(actor, actor, models.CreateRepoOptions{
+		Name:        "repo-pr-update",
+		Description: "repo-tmp-pr-update description",
+		AutoInit:    true,
+		Gitignores:  "C,C++",
+		License:     "MIT",
+		Readme:      "Default",
+		IsPrivate:   false,
+	})
+	assert.NoError(t, err)
+	assert.NotEmpty(t, baseRepo)
+
+	headRepo, err := repo_module.ForkRepository(actor, forkOrg, baseRepo, "repo-pr-update", "desc")
+	assert.NoError(t, err)
+	assert.NotEmpty(t, headRepo)
+
+	//create a commit on base Repo
+	_, err = repofiles.CreateOrUpdateRepoFile(baseRepo, actor, &repofiles.UpdateRepoFileOptions{
+		TreePath:  "File_A",
+		Message:   "Add File A",
+		Content:   "File A",
+		IsNewFile: true,
+		OldBranch: "master",
+		NewBranch: "master",
+		Author: &repofiles.IdentityOptions{
+			Name:  actor.Name,
+			Email: actor.Email,
+		},
+		Committer: &repofiles.IdentityOptions{
+			Name:  actor.Name,
+			Email: actor.Email,
+		},
+		Dates: &repofiles.CommitDateOptions{
+			Author:    time.Now(),
+			Committer: time.Now(),
+		},
+	})
+	assert.NoError(t, err)
+
+	//create a commit on head Repo
+	_, err = repofiles.CreateOrUpdateRepoFile(headRepo, actor, &repofiles.UpdateRepoFileOptions{
+		TreePath:  "File_B",
+		Message:   "Add File on PR branch",
+		Content:   "File B",
+		IsNewFile: true,
+		OldBranch: "master",
+		NewBranch: "newBranch",
+		Author: &repofiles.IdentityOptions{
+			Name:  actor.Name,
+			Email: actor.Email,
+		},
+		Committer: &repofiles.IdentityOptions{
+			Name:  actor.Name,
+			Email: actor.Email,
+		},
+		Dates: &repofiles.CommitDateOptions{
+			Author:    time.Now(),
+			Committer: time.Now(),
+		},
+	})
+	assert.NoError(t, err)
+
+	//create Pull
+	pullIssue := &models.Issue{
+		RepoID:   baseRepo.ID,
+		Title:    "Test Pull -to-update-",
+		PosterID: actor.ID,
+		Poster:   actor,
+		IsPull:   true,
+	}
+	pullRequest := &models.PullRequest{
+		HeadRepoID: headRepo.ID,
+		BaseRepoID: baseRepo.ID,
+		HeadBranch: "newBranch",
+		BaseBranch: "master",
+		HeadRepo:   headRepo,
+		BaseRepo:   baseRepo,
+		Type:       models.PullRequestGitea,
+	}
+	err = pull_service.NewPullRequest(baseRepo, pullIssue, nil, nil, pullRequest, nil)
+	assert.NoError(t, err)
+
+	issue := models.AssertExistsAndLoadBean(t, &models.Issue{Title: "Test Pull -to-update-"}).(*models.Issue)
+	pr, err := models.GetPullRequestByIssueID(issue.ID)
+	assert.NoError(t, err)
+
+	return pr
+}

integrations/repo_activity_test.go

@@ -56,9 +56,9 @@ func TestRepoActivity(t *testing.T) {
 		list = htmlDoc.doc.Find("#merged-pull-requests").Next().Find("p.desc")
 		assert.Len(t, list.Nodes, 1)
 
-		// Should be 2 merged proposed pull requests
+		// Should be 3 merged proposed pull requests
 		list = htmlDoc.doc.Find("#proposed-pull-requests").Next().Find("p.desc")
-		assert.Len(t, list.Nodes, 2)
+		assert.Len(t, list.Nodes, 3)
 
 		// Should be 3 new issues
 		list = htmlDoc.doc.Find("#new-issues").Next().Find("p.desc")

models/fixtures/issue.yml

@@ -122,3 +122,15 @@
   created_unix: 946684830
   updated_unix: 999307200
   deadline_unix: 1019307200
+
+-
+  id: 11
+  repo_id: 1
+  index: 5
+  poster_id: 1
+  name: pull5
+  content: content for the a pull request
+  is_closed: false
+  is_pull: true
+  created_unix: 1579194806
+  updated_unix: 1579194806

models/fixtures/pull_request.yml

@@ -49,4 +49,17 @@
   head_branch: branch1
   base_branch: master
   merge_base: abcdef1234567890
-  has_merged: false
+  has_merged: false
+
+-
+  id: 5 # this PR is outdated (one commit behind branch1 )
+  type: 0 # gitea pull request
+  status: 2 # mergable
+  issue_id: 11
+  index: 5
+  head_repo_id: 1
+  base_repo_id: 1
+  head_branch: pr-to-update
+  base_branch: branch1
+  merge_base: 1234567890abcdef
+  has_merged: false

models/fixtures/repository.yml

@@ -7,7 +7,7 @@
   is_private: false
   num_issues: 2
   num_closed_issues: 1
-  num_pulls: 2
+  num_pulls: 3
   num_closed_pulls: 0
   num_milestones: 3
   num_closed_milestones: 1

models/issue_test.go

@@ -276,8 +276,8 @@ func TestIssue_SearchIssueIDsByKeyword(t *testing.T) {
 
 	total, ids, err = SearchIssueIDsByKeyword("for", []int64{1}, 10, 0)
 	assert.NoError(t, err)
-	assert.EqualValues(t, 4, total)
-	assert.EqualValues(t, []int64{1, 2, 3, 5}, ids)
+	assert.EqualValues(t, 5, total)
+	assert.EqualValues(t, []int64{1, 2, 3, 5, 11}, ids)
 
 	// issue1's comment id 2
 	total, ids, err = SearchIssueIDsByKeyword("good", []int64{1}, 10, 0)
@@ -305,8 +305,8 @@ func testInsertIssue(t *testing.T, title, content string) {
 	assert.True(t, has)
 	assert.EqualValues(t, issue.Title, newIssue.Title)
 	assert.EqualValues(t, issue.Content, newIssue.Content)
-	// there are 4 issues and max index is 4 on repository 1, so this one should 5
-	assert.EqualValues(t, 5, newIssue.Index)
+	// there are 5 issues and max index is 5 on repository 1, so this one should 6
+	assert.EqualValues(t, 6, newIssue.Index)
 
 	_, err = x.ID(issue.ID).Delete(new(Issue))
 	assert.NoError(t, err)

models/issue_user_test.go

@@ -17,7 +17,7 @@ func Test_newIssueUsers(t *testing.T) {
 	newIssue := &Issue{
 		RepoID:   repo.ID,
 		PosterID: 4,
-		Index:    5,
+		Index:    6,
 		Title:    "newTestIssueTitle",
 		Content:  "newTestIssueContent",
 	}

models/pull.go

@@ -742,3 +742,8 @@ func (pr *PullRequest) IsHeadEqualWithBranch(branchName string) (bool, error) {
 	}
 	return baseCommit.HasPreviousCommit(headCommit.ID)
 }
+
+// IsSameRepo returns true if base repo and head repo is the same
+func (pr *PullRequest) IsSameRepo() bool {
+	return pr.BaseRepoID == pr.HeadRepoID
+}

models/pull_test.go

@@ -61,10 +61,11 @@ func TestPullRequestsNewest(t *testing.T) {
 		Labels:   []string{},
 	})
 	assert.NoError(t, err)
-	assert.Equal(t, int64(2), count)
-	if assert.Len(t, prs, 2) {
-		assert.Equal(t, int64(2), prs[0].ID)
-		assert.Equal(t, int64(1), prs[1].ID)
+	assert.EqualValues(t, 3, count)
+	if assert.Len(t, prs, 3) {
+		assert.EqualValues(t, 5, prs[0].ID)
+		assert.EqualValues(t, 2, prs[1].ID)
+		assert.EqualValues(t, 1, prs[2].ID)
 	}
 }
 
@@ -77,10 +78,11 @@ func TestPullRequestsOldest(t *testing.T) {
 		Labels:   []string{},
 	})
 	assert.NoError(t, err)
-	assert.Equal(t, int64(2), count)
-	if assert.Len(t, prs, 2) {
-		assert.Equal(t, int64(1), prs[0].ID)
-		assert.Equal(t, int64(2), prs[1].ID)
+	assert.EqualValues(t, 3, count)
+	if assert.Len(t, prs, 3) {
+		assert.EqualValues(t, 1, prs[0].ID)
+		assert.EqualValues(t, 2, prs[1].ID)
+		assert.EqualValues(t, 5, prs[2].ID)
 	}
 }
 

modules/indexer/issues/indexer_test.go

@@ -65,7 +65,7 @@ func TestBleveSearchIssues(t *testing.T) {
 
 	ids, err = SearchIssuesByKeyword([]int64{1}, "for")
 	assert.NoError(t, err)
-	assert.EqualValues(t, []int64{1, 2, 3, 5}, ids)
+	assert.EqualValues(t, []int64{1, 2, 3, 5, 11}, ids)
 
 	ids, err = SearchIssuesByKeyword([]int64{1}, "good")
 	assert.NoError(t, err)
@@ -89,7 +89,7 @@ func TestDBSearchIssues(t *testing.T) {
 
 	ids, err = SearchIssuesByKeyword([]int64{1}, "for")
 	assert.NoError(t, err)
-	assert.EqualValues(t, []int64{1, 2, 3, 5}, ids)
+	assert.EqualValues(t, []int64{1, 2, 3, 5, 11}, ids)
 
 	ids, err = SearchIssuesByKeyword([]int64{1}, "good")
 	assert.NoError(t, err)

options/locale/locale_en-US.ini

@@ -1082,6 +1082,10 @@ pulls.open_unmerged_pull_exists = `You cannot perform a reopen operation because
 pulls.status_checking = Some checks are pending
 pulls.status_checks_success = All checks were successful
 pulls.status_checks_error = Some checks failed
+pulls.update_branch = Update branch
+pulls.update_branch_success = Branch update was successful
+pulls.update_not_allowed = You are not allowed to update branch
+pulls.outdated_with_base_branch = This branch is out-of-date with the base branch
 
 milestones.new = New Milestone
 milestones.open_tab = %d Open

routers/repo/pull.go

@@ -14,6 +14,7 @@ import (
 	"net/http"
 	"path"
 	"strings"
+	"time"
 
 	"code.gitea.io/gitea/models"
 	"code.gitea.io/gitea/modules/auth"
@@ -342,8 +343,21 @@ func PrepareViewPullInfo(ctx *context.Context, issue *models.Issue) *git.Compare
 
 	setMergeTarget(ctx, pull)
 
+	divergence, err := pull_service.GetDiverging(pull)
+	if err != nil {
+		ctx.ServerError("GetDiverging", err)
+		return nil
+	}
+	ctx.Data["Divergence"] = divergence
+	allowUpdate, err := pull_service.IsUserAllowedToUpdate(pull, ctx.User)
+	if err != nil {
+		ctx.ServerError("GetDiverging", err)
+		return nil
+	}
+	ctx.Data["UpdateAllowed"] = allowUpdate
+
 	if err := pull.LoadProtectedBranch(); err != nil {
-		ctx.ServerError("GetLatestCommitStatus", err)
+		ctx.ServerError("LoadProtectedBranch", err)
 		return nil
 	}
 	ctx.Data["EnableStatusCheck"] = pull.ProtectedBranch != nil && pull.ProtectedBranch.EnableStatusCheck
@@ -587,6 +601,72 @@ func ViewPullFiles(ctx *context.Context) {
 	ctx.HTML(200, tplPullFiles)
 }
 
+// UpdatePullRequest merge master into PR
+func UpdatePullRequest(ctx *context.Context) {
+	issue := checkPullInfo(ctx)
+	if ctx.Written() {
+		return
+	}
+	if issue.IsClosed {
+		ctx.NotFound("MergePullRequest", nil)
+		return
+	}
+	if issue.PullRequest.HasMerged {
+		ctx.NotFound("MergePullRequest", nil)
+		return
+	}
+
+	if err := issue.PullRequest.LoadBaseRepo(); err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+	if err := issue.PullRequest.LoadHeadRepo(); err != nil {
+		ctx.InternalServerError(err)
+		return
+	}
+
+	allowedUpdate, err := pull_service.IsUserAllowedToUpdate(issue.PullRequest, ctx.User)
+	if err != nil {
+		ctx.ServerError("IsUserAllowedToMerge", err)
+		return
+	}
+
+	// ToDo: add check if maintainers are allowed to change branch ... (need migration & co)
+	if !allowedUpdate {
+		ctx.Flash.Error(ctx.Tr("repo.pulls.update_not_allowed"))
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+		return
+	}
+
+	// default merge commit message
+	message := fmt.Sprintf("Merge branch '%s' into %s", issue.PullRequest.BaseBranch, issue.PullRequest.HeadBranch)
+
+	if err = pull_service.Update(issue.PullRequest, ctx.User, message); err != nil {
+		sanitize := func(x string) string {
+			runes := []rune(x)
+
+			if len(runes) > 512 {
+				x = "..." + string(runes[len(runes)-512:])
+			}
+
+			return strings.Replace(html.EscapeString(x), "\n", "<br>", -1)
+		}
+		if models.IsErrMergeConflicts(err) {
+			conflictError := err.(models.ErrMergeConflicts)
+			ctx.Flash.Error(ctx.Tr("repo.pulls.merge_conflict", sanitize(conflictError.StdErr), sanitize(conflictError.StdOut)))
+			ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+			return
+		}
+		ctx.Flash.Error(err.Error())
+		ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+	}
+
+	time.Sleep(1 * time.Second)
+
+	ctx.Flash.Success(ctx.Tr("repo.pulls.update_branch_success"))
+	ctx.Redirect(ctx.Repo.RepoLink + "/pulls/" + com.ToStr(issue.Index))
+}
+
 // MergePullRequest response for merging pull request
 func MergePullRequest(ctx *context.Context, form auth.MergePullRequestForm) {
 	issue := checkPullInfo(ctx)

routers/routes/routes.go

@@ -855,6 +855,7 @@ func RegisterRoutes(m *macaron.Macaron) {
 			m.Get(".patch", repo.DownloadPullPatch)
 			m.Get("/commits", context.RepoRef(), repo.ViewPullCommits)
 			m.Post("/merge", context.RepoMustNotBeArchived(), reqRepoPullsWriter, bindIgnErr(auth.MergePullRequestForm{}), repo.MergePullRequest)
+			m.Post("/update", repo.UpdatePullRequest)
 			m.Post("/cleanup", context.RepoMustNotBeArchived(), context.RepoRef(), repo.CleanUpPullRequest)
 			m.Group("/files", func() {
 				m.Get("", context.RepoRef(), repo.SetEditorconfigIfExists, repo.SetDiffViewStyle, repo.SetWhitespaceBehavior, repo.ViewPullFiles)

services/pull/merge.go

@@ -33,11 +33,6 @@ import (
 // Caller should check PR is ready to be merged (review and status checks)
 // FIXME: add repoWorkingPull make sure two merges does not happen at same time.
 func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repository, mergeStyle models.MergeStyle, message string) (err error) {
-	binVersion, err := git.BinVersion()
-	if err != nil {
-		log.Error("git.BinVersion: %v", err)
-		return fmt.Errorf("Unable to get git version: %v", err)
-	}
 
 	if err = pr.GetHeadRepo(); err != nil {
 		log.Error("GetHeadRepo: %v", err)
@@ -63,6 +58,61 @@ func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repositor
 		go AddTestPullRequestTask(doer, pr.BaseRepo.ID, pr.BaseBranch, false, "", "")
 	}()
 
+	if err := rawMerge(pr, doer, mergeStyle, message); err != nil {
+		return err
+	}
+
+	pr.MergedCommitID, err = baseGitRepo.GetBranchCommitID(pr.BaseBranch)
+	if err != nil {
+		return fmt.Errorf("GetBranchCommit: %v", err)
+	}
+
+	pr.MergedUnix = timeutil.TimeStampNow()
+	pr.Merger = doer
+	pr.MergerID = doer.ID
+
+	if err = pr.SetMerged(); err != nil {
+		log.Error("setMerged [%d]: %v", pr.ID, err)
+	}
+
+	notification.NotifyMergePullRequest(pr, doer)
+
+	// Reset cached commit count
+	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
+
+	// Resolve cross references
+	refs, err := pr.ResolveCrossReferences()
+	if err != nil {
+		log.Error("ResolveCrossReferences: %v", err)
+		return nil
+	}
+
+	for _, ref := range refs {
+		if err = ref.LoadIssue(); err != nil {
+			return err
+		}
+		if err = ref.Issue.LoadRepo(); err != nil {
+			return err
+		}
+		close := (ref.RefAction == references.XRefActionCloses)
+		if close != ref.Issue.IsClosed {
+			if err = issue_service.ChangeStatus(ref.Issue, doer, close); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}
+
+// rawMerge perform the merge operation without changing any pull information in database
+func rawMerge(pr *models.PullRequest, doer *models.User, mergeStyle models.MergeStyle, message string) (err error) {
+	binVersion, err := git.BinVersion()
+	if err != nil {
+		log.Error("git.BinVersion: %v", err)
+		return fmt.Errorf("Unable to get git version: %v", err)
+	}
+
 	// Clone base repo.
 	tmpBasePath, err := createTemporaryRepo(pr)
 	if err != nil {
@@ -337,46 +387,6 @@ func Merge(pr *models.PullRequest, doer *models.User, baseGitRepo *git.Repositor
 	outbuf.Reset()
 	errbuf.Reset()
 
-	pr.MergedCommitID, err = baseGitRepo.GetBranchCommitID(pr.BaseBranch)
-	if err != nil {
-		return fmt.Errorf("GetBranchCommit: %v", err)
-	}
-
-	pr.MergedUnix = timeutil.TimeStampNow()
-	pr.Merger = doer
-	pr.MergerID = doer.ID
-
-	if err = pr.SetMerged(); err != nil {
-		log.Error("setMerged [%d]: %v", pr.ID, err)
-	}
-
-	notification.NotifyMergePullRequest(pr, doer)
-
-	// Reset cached commit count
-	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
-
-	// Resolve cross references
-	refs, err := pr.ResolveCrossReferences()
-	if err != nil {
-		log.Error("ResolveCrossReferences: %v", err)
-		return nil
-	}
-
-	for _, ref := range refs {
-		if err = ref.LoadIssue(); err != nil {
-			return err
-		}
-		if err = ref.Issue.LoadRepo(); err != nil {
-			return err
-		}
-		close := (ref.RefAction == references.XRefActionCloses)
-		if close != ref.Issue.IsClosed {
-			if err = issue_service.ChangeStatus(ref.Issue, doer, close); err != nil {
-				return err
-			}
-		}
-	}
-
 	return nil
 }
 

services/pull/update.go

@@ -0,0 +1,125 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package pull
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/git"
+	"code.gitea.io/gitea/modules/log"
+)
+
+// Update updates pull request with base branch.
+func Update(pull *models.PullRequest, doer *models.User, message string) error {
+	//use merge functions but switch repo's and branch's
+	pr := &models.PullRequest{
+		HeadRepoID: pull.BaseRepoID,
+		BaseRepoID: pull.HeadRepoID,
+		HeadBranch: pull.BaseBranch,
+		BaseBranch: pull.HeadBranch,
+	}
+
+	if err := pr.LoadHeadRepo(); err != nil {
+		log.Error("LoadHeadRepo: %v", err)
+		return fmt.Errorf("LoadHeadRepo: %v", err)
+	} else if err = pr.LoadBaseRepo(); err != nil {
+		log.Error("LoadBaseRepo: %v", err)
+		return fmt.Errorf("LoadBaseRepo: %v", err)
+	}
+
+	diffCount, err := GetDiverging(pull)
+	if err != nil {
+		return err
+	} else if diffCount.Behind == 0 {
+		return fmt.Errorf("HeadBranch of PR %d is up to date", pull.Index)
+	}
+
+	defer func() {
+		go AddTestPullRequestTask(doer, pr.HeadRepo.ID, pr.HeadBranch, false, "", "")
+	}()
+
+	return rawMerge(pr, doer, models.MergeStyleMerge, message)
+}
+
+// IsUserAllowedToUpdate check if user is allowed to update PR with given permissions and branch protections
+func IsUserAllowedToUpdate(pull *models.PullRequest, user *models.User) (bool, error) {
+	headRepoPerm, err := models.GetUserRepoPermission(pull.HeadRepo, user)
+	if err != nil {
+		return false, err
+	}
+
+	pr := &models.PullRequest{
+		HeadRepoID: pull.BaseRepoID,
+		BaseRepoID: pull.HeadRepoID,
+		HeadBranch: pull.BaseBranch,
+		BaseBranch: pull.HeadBranch,
+	}
+	return IsUserAllowedToMerge(pr, headRepoPerm, user)
+}
+
+// GetDiverging determines how many commits a PR is ahead or behind the PR base branch
+func GetDiverging(pr *models.PullRequest) (*git.DivergeObject, error) {
+	log.Trace("PushToBaseRepo[%d]: pushing commits to base repo '%s'", pr.BaseRepoID, pr.GetGitRefName())
+	if err := pr.LoadBaseRepo(); err != nil {
+		return nil, err
+	}
+	if err := pr.LoadHeadRepo(); err != nil {
+		return nil, err
+	}
+
+	headRepoPath := pr.HeadRepo.RepoPath()
+	headGitRepo, err := git.OpenRepository(headRepoPath)
+	if err != nil {
+		return nil, fmt.Errorf("OpenRepository: %v", err)
+	}
+	defer headGitRepo.Close()
+
+	if pr.IsSameRepo() {
+		diff, err := git.GetDivergingCommits(pr.HeadRepo.RepoPath(), pr.BaseBranch, pr.HeadBranch)
+		return &diff, err
+	}
+
+	tmpRemoteName := fmt.Sprintf("tmp-pull-%d-base", pr.ID)
+	if err = headGitRepo.AddRemote(tmpRemoteName, pr.BaseRepo.RepoPath(), true); err != nil {
+		return nil, fmt.Errorf("headGitRepo.AddRemote: %v", err)
+	}
+	// Make sure to remove the remote even if the push fails
+	defer func() {
+		if err := headGitRepo.RemoveRemote(tmpRemoteName); err != nil {
+			log.Error("CountDiverging: RemoveRemote: %s", err)
+		}
+	}()
+
+	// $(git rev-list --count tmp-pull-1-base/master..feature) commits ahead of master
+	ahead, errorAhead := checkDivergence(headRepoPath, fmt.Sprintf("%s/%s", tmpRemoteName, pr.BaseBranch), pr.HeadBranch)
+	if errorAhead != nil {
+		return &git.DivergeObject{}, errorAhead
+	}
+
+	// $(git rev-list --count feature..tmp-pull-1-base/master) commits behind master
+	behind, errorBehind := checkDivergence(headRepoPath, pr.HeadBranch, fmt.Sprintf("%s/%s", tmpRemoteName, pr.BaseBranch))
+	if errorBehind != nil {
+		return &git.DivergeObject{}, errorBehind
+	}
+
+	return &git.DivergeObject{Ahead: ahead, Behind: behind}, nil
+}
+
+func checkDivergence(repoPath string, baseBranch string, targetBranch string) (int, error) {
+	branches := fmt.Sprintf("%s..%s", baseBranch, targetBranch)
+	cmd := git.NewCommand("rev-list", "--count", branches)
+	stdout, err := cmd.RunInDir(repoPath)
+	if err != nil {
+		return -1, err
+	}
+	outInteger, errInteger := strconv.Atoi(strings.Trim(stdout, "\n"))
+	if errInteger != nil {
+		return -1, errInteger
+	}
+	return outInteger, nil
+}

templates/repo/issue/view_content/pull.tmpl

@@ -157,6 +157,26 @@
 							{{$.i18n.Tr (printf "repo.signing.wont_sign.%s" .WontSignReason) }}
 						</div>
 					{{end}}
+					{{if and .Divergence (gt .Divergence.Behind 0)}}
+					<div class="ui very compact branch-update grid">
+  						<div class="row">
+							<div class="item text gray eleven wide left floated column">
+								<i class="icon icon-octicon"><span class="octicon octicon-alert"></span></i>
+								{{$.i18n.Tr "repo.pulls.outdated_with_base_branch"}}
+							</div>
+							{{if .UpdateAllowed}}
+								<div class="item text five wide right floated column">
+									<form action="{{.Link}}/update" method="post">
+										{{.CsrfTokenHtml}}
+										<button class="ui button" data-do="update">
+											<span class="item text">{{$.i18n.Tr "repo.pulls.update_branch"}}</span>
+										</button>
+									</form>
+								</div>
+							{{end}}
+						</div>
+					</div>
+					{{end}}
 					{{if .AllowMerge}}
 						{{$prUnit := .Repository.MustGetUnit $.UnitTypePullRequests}}
 						{{$approvers := .Issue.PullRequest.GetApprovers}}

web_src/less/_repository.less

@@ -655,6 +655,13 @@
                 .icon-octicon {
                     padding-left: 2px;
                 }
+                .branch-update.grid {
+                    margin-bottom: -1.5rem;
+                    margin-top: -0.5rem;
+                    .row {
+                        padding-bottom: 0;
+                    }
+                }
             }
 
             .review-item {