Retarget depending pulls when the parent branch is deleted (#28686)

Sometimes you need to work on a feature which depends on another (unmerged) feature.
In this case, you may create a PR based on that feature instead of the main branch.
Currently, such PRs will be closed without the possibility to reopen in case the parent feature is merged and its branch is deleted.
Automatic target branch change make life a lot easier in such cases.
Github and Bitbucket behave in such way.

Example:
$PR_1$: main <- feature1
$PR_2$: feature1 <- feature2

Currently, merging $PR_1$ and deleting its branch leads to $PR_2$ being closed without the possibility to reopen.
This is both annoying and loses the review history when you open a new PR.

With this change, $PR_2$ will change its target branch to main ($PR_2$: main <- feature2) after $PR_1$ has been merged and its branch has been deleted.

This behavior is enabled by default but can be disabled.
For security reasons, this target branch change will not be executed when merging PRs targeting another repo. 

Fixes #27062
Fixes #18408

---------

Co-authored-by: Denys Konovalov <kontakt@denyskon.de>
Co-authored-by: delvh <dev.lh@web.de>

custom/conf/app.example.ini

@@ -1067,6 +1067,9 @@ LEVEL = Info
 ;;
 ;; In addition to testing patches using the three-way merge method, re-test conflicting patches with git apply
 ;TEST_CONFLICTING_PATCHES_WITH_GIT_APPLY = false
+;;
+;; Retarget child pull requests to the parent pull request branch target on merge of parent pull request. It only works on merged PRs where the head and base branch target the same repo.
+;RETARGET_CHILDREN_ON_MERGE = true
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

docs/content/administration/config-cheat-sheet.en-us.md

@@ -135,6 +135,7 @@ In addition, there is _`StaticRootPath`_ which can be set as a built-in at build
 - `POPULATE_SQUASH_COMMENT_WITH_COMMIT_MESSAGES`: **false**: In default squash-merge messages include the commit message of all commits comprising the pull request.
 - `ADD_CO_COMMITTER_TRAILERS`: **true**: Add co-authored-by and co-committed-by trailers to merge commit messages if committer does not match author.
 - `TEST_CONFLICTING_PATCHES_WITH_GIT_APPLY`: **false**: PR patches are tested using a three-way merge method to discover if there are conflicts. If this setting is set to **true**, conflicting patches will be retested using `git apply` - This was the previous behaviour in 1.18 (and earlier) but is somewhat inefficient. Please report if you find that this setting is required.
+- `RETARGET_CHILDREN_ON_MERGE`: **true**: Retarget child pull requests to the parent pull request branch target on merge of parent pull request. It only works on merged PRs where the head and base branch target the same repo.
 
 ### Repository - Issue (`repository.issue`)
 

modules/setting/repository.go

@@ -85,6 +85,7 @@ var (
 			PopulateSquashCommentWithCommitMessages  bool
 			AddCoCommitterTrailers                   bool
 			TestConflictingPatchesWithGitApply       bool
+			RetargetChildrenOnMerge                  bool
 		} `ini:"repository.pull-request"`
 
 		// Issue Setting
@@ -209,6 +210,7 @@ var (
 			PopulateSquashCommentWithCommitMessages  bool
 			AddCoCommitterTrailers                   bool
 			TestConflictingPatchesWithGitApply       bool
+			RetargetChildrenOnMerge                  bool
 		}{
 			WorkInProgressPrefixes: []string{"WIP:", "[WIP]"},
 			// Same as GitHub. See
@@ -223,6 +225,7 @@ var (
 			DefaultMergeMessageOfficialApproversOnly: true,
 			PopulateSquashCommentWithCommitMessages:  false,
 			AddCoCommitterTrailers:                   true,
+			RetargetChildrenOnMerge:                  true,
 		},
 
 		// Issue settings

routers/api/v1/repo/pull.go

@@ -913,6 +913,10 @@ 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 {
 			switch {
 			case git.IsErrBranchNotExist(err):

routers/web/repo/pull.go

@@ -1587,6 +1587,12 @@ 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 {
 		switch {
 		case git.IsErrBranchNotExist(err):

services/pull/pull.go

@@ -546,6 +546,43 @@ func (errs errlist) Error() string {
 	return ""
 }
 
+// RetargetChildrenOnMerge retarget children pull requests on merge if possible
+func RetargetChildrenOnMerge(ctx context.Context, doer *user_model.User, pr *issues_model.PullRequest) error {
+	if setting.Repository.PullRequest.RetargetChildrenOnMerge && pr.BaseRepoID == pr.HeadRepoID {
+		return RetargetBranchPulls(ctx, doer, pr.HeadRepoID, pr.HeadBranch, pr.BaseBranch)
+	}
+	return nil
+}
+
+// RetargetBranchPulls change target branch for all pull requests whose base branch is the branch
+// Both branch and targetBranch must be in the same repo (for security reasons)
+func RetargetBranchPulls(ctx context.Context, doer *user_model.User, repoID int64, branch, targetBranch string) error {
+	prs, err := issues_model.GetUnmergedPullRequestsByBaseInfo(ctx, repoID, branch)
+	if err != nil {
+		return err
+	}
+
+	if err := issues_model.PullRequestList(prs).LoadAttributes(ctx); err != nil {
+		return err
+	}
+
+	var errs errlist
+	for _, pr := range prs {
+		if err = pr.Issue.LoadRepo(ctx); err != nil {
+			errs = append(errs, err)
+		} else if err = ChangeTargetBranch(ctx, pr, doer, targetBranch); err != nil &&
+			!issues_model.IsErrIssueIsClosed(err) && !models.IsErrPullRequestHasMerged(err) &&
+			!issues_model.IsErrPullRequestAlreadyExists(err) {
+			errs = append(errs, err)
+		}
+	}
+
+	if len(errs) > 0 {
+		return errs
+	}
+	return nil
+}
+
 // CloseBranchPulls close all the pull requests who's head branch is the branch
 func CloseBranchPulls(ctx context.Context, doer *user_model.User, repoID int64, branch string) error {
 	prs, err := issues_model.GetUnmergedPullRequestsByHeadInfo(ctx, repoID, branch)

tests/integration/pull_create_test.go

@@ -17,7 +17,7 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func testPullCreate(t *testing.T, session *TestSession, user, repo, branch, title string) *httptest.ResponseRecorder {
+func testPullCreate(t *testing.T, session *TestSession, user, repo string, toSelf bool, targetBranch, sourceBranch, title string) *httptest.ResponseRecorder {
 	req := NewRequest(t, "GET", path.Join(user, repo))
 	resp := session.MakeRequest(t, req, http.StatusOK)
 
@@ -25,8 +25,21 @@ func testPullCreate(t *testing.T, session *TestSession, user, repo, branch, titl
 	htmlDoc := NewHTMLParser(t, resp.Body)
 	link, exists := htmlDoc.doc.Find("#new-pull-request").Attr("href")
 	assert.True(t, exists, "The template has changed")
-	if branch != "master" {
+
-		link = strings.Replace(link, ":master", ":"+branch, 1)
+	targetUser := strings.Split(link, "/")[1]
+	if toSelf && targetUser != user {
+		link = strings.Replace(link, targetUser, user, 1)
+	}
+
+	if targetBranch != "master" {
+		link = strings.Replace(link, "master...", targetBranch+"...", 1)
+	}
+	if sourceBranch != "master" {
+		if targetUser == user {
+			link = strings.Replace(link, "...master", "..."+sourceBranch, 1)
+		} else {
+			link = strings.Replace(link, ":master", ":"+sourceBranch, 1)
+		}
 	}
 
 	req = NewRequest(t, "GET", link)
@@ -49,7 +62,7 @@ func TestPullCreate(t *testing.T) {
 		session := loginUser(t, "user1")
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 
 		// check the redirected URL
 		url := test.RedirectURL(resp)
@@ -77,7 +90,7 @@ func TestPullCreate_TitleEscape(t *testing.T) {
 		session := loginUser(t, "user1")
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "<i>XSS PR</i>")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "<i>XSS PR</i>")
 
 		// check the redirected URL
 		url := test.RedirectURL(resp)
@@ -142,7 +155,7 @@ func TestPullBranchDelete(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testCreateBranch(t, session, "user1", "repo1", "branch/master", "master1", http.StatusSeeOther)
 		testEditFile(t, session, "user1", "repo1", "master1", "README.md", "Hello, World (Edited)\n")
-		resp := testPullCreate(t, session, "user1", "repo1", "master1", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master1", "This is a pull title")
 
 		// check the redirected URL
 		url := test.RedirectURL(resp)

tests/integration/pull_merge_test.go

@@ -35,16 +35,23 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-func testPullMerge(t *testing.T, session *TestSession, user, repo, pullnum string, mergeStyle repo_model.MergeStyle) *httptest.ResponseRecorder {
+func testPullMerge(t *testing.T, session *TestSession, user, repo, pullnum string, mergeStyle repo_model.MergeStyle, deleteBranch bool) *httptest.ResponseRecorder {
 	req := NewRequest(t, "GET", path.Join(user, repo, "pulls", pullnum))
 	resp := session.MakeRequest(t, req, http.StatusOK)
 
 	htmlDoc := NewHTMLParser(t, resp.Body)
 	link := path.Join(user, repo, "pulls", pullnum, "merge")
-	req = NewRequestWithValues(t, "POST", link, map[string]string{
+
+	options := map[string]string{
 		"_csrf": htmlDoc.GetCSRF(),
 		"do":    string(mergeStyle),
-	})
+	}
+
+	if deleteBranch {
+		options["delete_branch_after_merge"] = "on"
+	}
+
+	req = NewRequestWithValues(t, "POST", link, options)
 	resp = session.MakeRequest(t, req, http.StatusOK)
 
 	respJSON := struct {
@@ -83,11 +90,11 @@ func TestPullMerge(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge, false)
 
 		hookTasks, err = webhook.HookTasks(db.DefaultContext, 1, 1)
 		assert.NoError(t, err)
@@ -105,11 +112,11 @@ func TestPullRebase(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleRebase)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleRebase, false)
 
 		hookTasks, err = webhook.HookTasks(db.DefaultContext, 1, 1)
 		assert.NoError(t, err)
@@ -127,11 +134,11 @@ func TestPullRebaseMerge(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleRebaseMerge)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleRebaseMerge, false)
 
 		hookTasks, err = webhook.HookTasks(db.DefaultContext, 1, 1)
 		assert.NoError(t, err)
@@ -150,11 +157,11 @@ func TestPullSquash(t *testing.T) {
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited!)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleSquash)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleSquash, false)
 
 		hookTasks, err = webhook.HookTasks(db.DefaultContext, 1, 1)
 		assert.NoError(t, err)
@@ -168,11 +175,11 @@ func TestPullCleanUpAfterMerge(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFileToNewBranch(t, session, "user1", "repo1", "master", "feature/test", "README.md", "Hello, World (Edited - TestPullCleanUpAfterMerge)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "feature/test", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "feature/test", "This is a pull title")
 
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge, false)
 
 		// Check PR branch deletion
 		resp = testPullCleanUp(t, session, elem[1], elem[2], elem[4])
@@ -203,7 +210,7 @@ func TestCantMergeWorkInProgress(t *testing.T) {
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
 
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "[wip] This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "[wip] This is a pull title")
 
 		req := NewRequest(t, "GET", test.RedirectURL(resp))
 		resp = session.MakeRequest(t, req, http.StatusOK)
@@ -435,3 +442,63 @@ func TestConflictChecking(t *testing.T) {
 		assert.False(t, conflictingPR.Mergeable(db.DefaultContext))
 	})
 }
+
+func TestPullRetargetChildOnBranchDelete(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, giteaURL *url.URL) {
+		session := loginUser(t, "user1")
+		testEditFileToNewBranch(t, session, "user2", "repo1", "master", "base-pr", "README.md", "Hello, World\n(Edited - TestPullRetargetOnCleanup - base PR)\n")
+		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
+		testEditFileToNewBranch(t, session, "user1", "repo1", "base-pr", "child-pr", "README.md", "Hello, World\n(Edited - TestPullRetargetOnCleanup - base PR)\n(Edited - TestPullRetargetOnCleanup - child PR)")
+
+		respBasePR := testPullCreate(t, session, "user2", "repo1", true, "master", "base-pr", "Base Pull Request")
+		elemBasePR := strings.Split(test.RedirectURL(respBasePR), "/")
+		assert.EqualValues(t, "pulls", elemBasePR[3])
+
+		respChildPR := testPullCreate(t, session, "user1", "repo1", false, "base-pr", "child-pr", "Child Pull Request")
+		elemChildPR := strings.Split(test.RedirectURL(respChildPR), "/")
+		assert.EqualValues(t, "pulls", elemChildPR[3])
+
+		testPullMerge(t, session, elemBasePR[1], elemBasePR[2], elemBasePR[4], repo_model.MergeStyleMerge, true)
+
+		// Check child PR
+		req := NewRequest(t, "GET", test.RedirectURL(respChildPR))
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		htmlDoc := NewHTMLParser(t, resp.Body)
+		targetBranch := htmlDoc.doc.Find("#branch_target>a").Text()
+		prStatus := strings.TrimSpace(htmlDoc.doc.Find(".issue-title-meta>.issue-state-label").Text())
+
+		assert.EqualValues(t, "master", targetBranch)
+		assert.EqualValues(t, "Open", prStatus)
+	})
+}
+
+func TestPullDontRetargetChildOnWrongRepo(t *testing.T) {
+	onGiteaRun(t, func(t *testing.T, giteaURL *url.URL) {
+		session := loginUser(t, "user1")
+		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
+		testEditFileToNewBranch(t, session, "user1", "repo1", "master", "base-pr", "README.md", "Hello, World\n(Edited - TestPullDontRetargetChildOnWrongRepo - base PR)\n")
+		testEditFileToNewBranch(t, session, "user1", "repo1", "base-pr", "child-pr", "README.md", "Hello, World\n(Edited - TestPullDontRetargetChildOnWrongRepo - base PR)\n(Edited - TestPullDontRetargetChildOnWrongRepo - child PR)")
+
+		respBasePR := testPullCreate(t, session, "user1", "repo1", false, "master", "base-pr", "Base Pull Request")
+		elemBasePR := strings.Split(test.RedirectURL(respBasePR), "/")
+		assert.EqualValues(t, "pulls", elemBasePR[3])
+
+		respChildPR := testPullCreate(t, session, "user1", "repo1", true, "base-pr", "child-pr", "Child Pull Request")
+		elemChildPR := strings.Split(test.RedirectURL(respChildPR), "/")
+		assert.EqualValues(t, "pulls", elemChildPR[3])
+
+		testPullMerge(t, session, elemBasePR[1], elemBasePR[2], elemBasePR[4], repo_model.MergeStyleMerge, true)
+
+		// Check child PR
+		req := NewRequest(t, "GET", test.RedirectURL(respChildPR))
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		htmlDoc := NewHTMLParser(t, resp.Body)
+		targetBranch := htmlDoc.doc.Find("#branch_target>a").Text()
+		prStatus := strings.TrimSpace(htmlDoc.doc.Find(".issue-title-meta>.issue-state-label").Text())
+
+		assert.EqualValues(t, "base-pr", targetBranch)
+		assert.EqualValues(t, "Closed", prStatus)
+	})
+}

tests/integration/repo_activity_test.go

@@ -22,16 +22,16 @@ func TestRepoActivity(t *testing.T) {
 		// Create PRs (1 merged & 2 proposed)
 		testRepoFork(t, session, "user2", "repo1", "user1", "repo1")
 		testEditFile(t, session, "user1", "repo1", "master", "README.md", "Hello, World (Edited)\n")
-		resp := testPullCreate(t, session, "user1", "repo1", "master", "This is a pull title")
+		resp := testPullCreate(t, session, "user1", "repo1", false, "master", "master", "This is a pull title")
 		elem := strings.Split(test.RedirectURL(resp), "/")
 		assert.EqualValues(t, "pulls", elem[3])
-		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge)
+		testPullMerge(t, session, elem[1], elem[2], elem[4], repo_model.MergeStyleMerge, false)
 
 		testEditFileToNewBranch(t, session, "user1", "repo1", "master", "feat/better_readme", "README.md", "Hello, World (Edited Again)\n")
-		testPullCreate(t, session, "user1", "repo1", "feat/better_readme", "This is a pull title")
+		testPullCreate(t, session, "user1", "repo1", false, "master", "feat/better_readme", "This is a pull title")
 
 		testEditFileToNewBranch(t, session, "user1", "repo1", "master", "feat/much_better_readme", "README.md", "Hello, World (Edited More)\n")
-		testPullCreate(t, session, "user1", "repo1", "feat/much_better_readme", "This is a pull title")
+		testPullCreate(t, session, "user1", "repo1", false, "master", "feat/much_better_readme", "This is a pull title")
 
 		// Create issues (3 new issues)
 		testNewIssue(t, session, "user2", "repo1", "Issue 1", "Description 1")