Add Pull Request merge options - Ignore white-space for conflict checking, Rebase, Squash merge (#3188)

* Pull request options migration and UI in settings

* Add ignore whitespace functionality

* Fix settings if pull requests are disabled

* Fix migration transaction

* Merge with Rebase functionality

* UI changes and related functionality for pull request merging button

* Implement squash functionality

* Fix rebase merging

* Fix pull request merge tests

* Add squash and rebase tests

* Fix API method to reuse default message functions

* Some refactoring and small fixes

* Remove more hardcoded values from tests

* Remove unneeded check from API method

* Fix variable name and comment typo

* Fix reset commit count after PR merge

models/error.go

@@ -878,6 +878,23 @@ func (err ErrPullRequestAlreadyExists) Error() string {
 		err.ID, err.IssueID, err.HeadRepoID, err.BaseRepoID, err.HeadBranch, err.BaseBranch)
 }
 
+// ErrInvalidMergeStyle represents an error if merging with disabled merge strategy
+type ErrInvalidMergeStyle struct {
+	ID    int64
+	Style MergeStyle
+}
+
+// IsErrInvalidMergeStyle checks if an error is a ErrInvalidMergeStyle.
+func IsErrInvalidMergeStyle(err error) bool {
+	_, ok := err.(ErrInvalidMergeStyle)
+	return ok
+}
+
+func (err ErrInvalidMergeStyle) Error() string {
+	return fmt.Sprintf("merge strategy is not allowed or is invalid [repo_id: %d, strategy: %s]",
+		err.ID, err.Style)
+}
+
 // _________                                       __
 // \_   ___ \  ____   _____   _____   ____   _____/  |_
 // /    \  \/ /  _ \ /     \ /     \_/ __ \ /    \   __\

models/fixtures/repo_unit.yml

@@ -30,7 +30,7 @@
   id: 5
   repo_id: 1
   type: 3
-  config: "{}"
+  config: "{\"IgnoreWhitespaceConflicts\":false,\"AllowMerge\":true,\"AllowRebase\":true,\"AllowSquash\":true}"
   created_unix: 946684810
 
 -
@@ -51,7 +51,7 @@
   id: 8
   repo_id: 3
   type: 3
-  config: "{}"
+  config: "{\"IgnoreWhitespaceConflicts\":true,\"AllowMerge\":true,\"AllowRebase\":false,\"AllowSquash\":false}"
   created_unix: 946684810
 
 -

models/migrations/migrations.go

@@ -160,6 +160,8 @@ var migrations = []Migration{
 	NewMigration("add lfs lock table", addLFSLock),
 	// v53 -> v54
 	NewMigration("add reactions", addReactions),
+	// v54 -> v55
+	NewMigration("add pull request options", addPullRequestOptions),
 }
 
 // Migrate database to current version

models/migrations/v54.go

@@ -0,0 +1,57 @@
+// Copyright 2017 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 migrations
+
+import (
+	"fmt"
+
+	"code.gitea.io/gitea/modules/util"
+
+	"github.com/go-xorm/xorm"
+)
+
+func addPullRequestOptions(x *xorm.Engine) error {
+	// RepoUnit describes all units of a repository
+	type RepoUnit struct {
+		ID          int64
+		RepoID      int64                  `xorm:"INDEX(s)"`
+		Type        int                    `xorm:"INDEX(s)"`
+		Config      map[string]interface{} `xorm:"JSON"`
+		CreatedUnix util.TimeStamp         `xorm:"INDEX CREATED"`
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	//Updating existing issue units
+	units := make([]*RepoUnit, 0, 100)
+	if err := sess.Where("`type` = ?", V16UnitTypePRs).Find(&units); err != nil {
+		return fmt.Errorf("Query repo units: %v", err)
+	}
+	for _, unit := range units {
+		if unit.Config == nil {
+			unit.Config = make(map[string]interface{})
+		}
+		if _, ok := unit.Config["IgnoreWhitespaceConflicts"]; !ok {
+			unit.Config["IgnoreWhitespaceConflicts"] = false
+		}
+		if _, ok := unit.Config["AllowMerge"]; !ok {
+			unit.Config["AllowMerge"] = true
+		}
+		if _, ok := unit.Config["AllowRebase"]; !ok {
+			unit.Config["AllowRebase"] = true
+		}
+		if _, ok := unit.Config["AllowSquash"]; !ok {
+			unit.Config["AllowSquash"] = true
+		}
+		if _, err := sess.ID(unit.ID).Cols("config").Update(unit); err != nil {
+			return err
+		}
+	}
+	return sess.Commit()
+}

models/pull.go

@@ -16,6 +16,7 @@ import (
 
 	"code.gitea.io/git"
 	"code.gitea.io/gitea/modules/base"
+	"code.gitea.io/gitea/modules/cache"
 	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/process"
 	"code.gitea.io/gitea/modules/setting"
@@ -109,6 +110,28 @@ func (pr *PullRequest) loadIssue(e Engine) (err error) {
 	return err
 }
 
+// GetDefaultMergeMessage returns default message used when merging pull request
+func (pr *PullRequest) GetDefaultMergeMessage() string {
+	if pr.HeadRepo == nil {
+		var err error
+		pr.HeadRepo, err = GetRepositoryByID(pr.HeadRepoID)
+		if err != nil {
+			log.Error(4, "GetRepositoryById[%d]: %v", pr.HeadRepoID, err)
+			return ""
+		}
+	}
+	return fmt.Sprintf("Merge branch '%s' of %s/%s into %s", pr.HeadBranch, pr.HeadUserName, pr.HeadRepo.Name, pr.BaseBranch)
+}
+
+// GetDefaultSquashMessage returns default message used when squash and merging pull request
+func (pr *PullRequest) GetDefaultSquashMessage() string {
+	if err := pr.LoadIssue(); err != nil {
+		log.Error(4, "LoadIssue: %v", err)
+		return ""
+	}
+	return fmt.Sprintf("%s (#%d)", pr.Issue.Title, pr.Issue.Index)
+}
+
 // APIFormat assumes following fields have been assigned with valid values:
 // Required - Issue
 // Optional - Merger
@@ -232,15 +255,38 @@ func (pr *PullRequest) CanAutoMerge() bool {
 	return pr.Status == PullRequestStatusMergeable
 }
 
+// MergeStyle represents the approach to merge commits into base branch.
+type MergeStyle string
+
+const (
+	// MergeStyleMerge create merge commit
+	MergeStyleMerge MergeStyle = "merge"
+	// MergeStyleRebase rebase before merging
+	MergeStyleRebase MergeStyle = "rebase"
+	// MergeStyleSquash squash commits into single commit before merging
+	MergeStyleSquash MergeStyle = "squash"
+)
+
 // Merge merges pull request to base repository.
 // FIXME: add repoWorkingPull make sure two merges does not happen at same time.
-func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository) (err error) {
+func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository, mergeStyle MergeStyle, message string) (err error) {
 	if err = pr.GetHeadRepo(); err != nil {
 		return fmt.Errorf("GetHeadRepo: %v", err)
 	} else if err = pr.GetBaseRepo(); err != nil {
 		return fmt.Errorf("GetBaseRepo: %v", err)
 	}
 
+	prUnit, err := pr.BaseRepo.GetUnit(UnitTypePullRequests)
+	if err != nil {
+		return err
+	}
+	prConfig := prUnit.PullRequestsConfig()
+
+	// Check if merge style is correct and allowed
+	if !prConfig.IsMergeStyleAllowed(mergeStyle) {
+		return ErrInvalidMergeStyle{pr.BaseRepo.ID, mergeStyle}
+	}
+
 	defer func() {
 		go HookQueue.Add(pr.BaseRepo.ID)
 		go AddTestPullRequestTask(doer, pr.BaseRepo.ID, pr.BaseBranch, false)
@@ -289,18 +335,62 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository) (err error
 		return fmt.Errorf("git fetch [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
 	}
 
-	if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
-		fmt.Sprintf("PullRequest.Merge (git merge --no-ff --no-commit): %s", tmpBasePath),
-		"git", "merge", "--no-ff", "--no-commit", "head_repo/"+pr.HeadBranch); err != nil {
-		return fmt.Errorf("git merge --no-ff --no-commit [%s]: %v - %s", tmpBasePath, err, stderr)
-	}
+	switch mergeStyle {
+	case MergeStyleMerge:
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git merge --no-ff --no-commit): %s", tmpBasePath),
+			"git", "merge", "--no-ff", "--no-commit", "head_repo/"+pr.HeadBranch); err != nil {
+			return fmt.Errorf("git merge --no-ff --no-commit [%s]: %v - %s", tmpBasePath, err, stderr)
+		}
 
-	sig := doer.NewGitSig()
-	if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
-		fmt.Sprintf("PullRequest.Merge (git merge): %s", tmpBasePath),
-		"git", "commit", fmt.Sprintf("--author='%s <%s>'", sig.Name, sig.Email),
-		"-m", fmt.Sprintf("Merge branch '%s' of %s/%s into %s", pr.HeadBranch, pr.HeadUserName, pr.HeadRepo.Name, pr.BaseBranch)); err != nil {
-		return fmt.Errorf("git commit [%s]: %v - %s", tmpBasePath, err, stderr)
+		sig := doer.NewGitSig()
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git merge): %s", tmpBasePath),
+			"git", "commit", fmt.Sprintf("--author='%s <%s>'", sig.Name, sig.Email),
+			"-m", message); err != nil {
+			return fmt.Errorf("git commit [%s]: %v - %s", tmpBasePath, err, stderr)
+		}
+	case MergeStyleRebase:
+		// Checkout head branch
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git checkout): %s", tmpBasePath),
+			"git", "checkout", "-b", "head_repo_"+pr.HeadBranch, "head_repo/"+pr.HeadBranch); err != nil {
+			return fmt.Errorf("git checkout: %s", stderr)
+		}
+		// Rebase before merging
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git rebase): %s", tmpBasePath),
+			"git", "rebase", "-q", pr.BaseBranch); err != nil {
+			return fmt.Errorf("git rebase [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
+		}
+		// Checkout base branch again
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git checkout): %s", tmpBasePath),
+			"git", "checkout", pr.BaseBranch); err != nil {
+			return fmt.Errorf("git checkout: %s", stderr)
+		}
+		// Merge fast forward
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git rebase): %s", tmpBasePath),
+			"git", "merge", "--ff-only", "-q", "head_repo_"+pr.HeadBranch); err != nil {
+			return fmt.Errorf("git merge --ff-only [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
+		}
+	case MergeStyleSquash:
+		// Merge with squash
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git squash): %s", tmpBasePath),
+			"git", "merge", "-q", "--squash", "head_repo/"+pr.HeadBranch); err != nil {
+			return fmt.Errorf("git merge --squash [%s -> %s]: %s", headRepoPath, tmpBasePath, stderr)
+		}
+		sig := pr.Issue.Poster.NewGitSig()
+		if _, stderr, err = process.GetManager().ExecDir(-1, tmpBasePath,
+			fmt.Sprintf("PullRequest.Merge (git squash): %s", tmpBasePath),
+			"git", "commit", fmt.Sprintf("--author='%s <%s>'", sig.Name, sig.Email),
+			"-m", message); err != nil {
+			return fmt.Errorf("git commit [%s]: %v - %s", tmpBasePath, err, stderr)
+		}
+	default:
+		return ErrInvalidMergeStyle{pr.BaseRepo.ID, mergeStyle}
 	}
 
 	// Push back to upstream.
@@ -327,6 +417,9 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository) (err error
 		log.Error(4, "MergePullRequestAction [%d]: %v", pr.ID, err)
 	}
 
+	// Reset cached commit count
+	cache.Remove(pr.Issue.Repo.GetCommitsCountCacheKey(pr.BaseBranch, true))
+
 	// Reload pull request information.
 	if err = pr.LoadAttributes(); err != nil {
 		log.Error(4, "LoadAttributes: %v", err)
@@ -349,7 +442,6 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository) (err error
 		return nil
 	}
 
-	// TODO: when squash commits, no need to append merge commit.
 	// It is possible that head branch is not fully sync with base branch for merge commits,
 	// so we need to get latest head commit and append merge commit manually
 	// to avoid strange diff commits produced.
@@ -358,12 +450,14 @@ func (pr *PullRequest) Merge(doer *User, baseGitRepo *git.Repository) (err error
 		log.Error(4, "GetBranchCommit: %v", err)
 		return nil
 	}
-	l.PushFront(mergeCommit)
+	if mergeStyle == MergeStyleMerge {
+		l.PushFront(mergeCommit)
+	}
 
 	p := &api.PushPayload{
 		Ref:        git.BranchPrefix + pr.BaseBranch,
 		Before:     pr.MergeBase,
-		After:      pr.MergedCommitID,
+		After:      mergeCommit.ID.String(),
 		CompareURL: setting.AppURL + pr.BaseRepo.ComposeCompareURL(pr.MergeBase, pr.MergedCommitID),
 		Commits:    ListToPushCommits(l).ToAPIPayloadCommits(pr.BaseRepo.HTMLURL()),
 		Repo:       pr.BaseRepo.APIFormat(AccessModeNone),
@@ -563,9 +657,21 @@ func (pr *PullRequest) testPatch() (err error) {
 		return fmt.Errorf("git read-tree --index-output=%s %s: %v - %s", indexTmpPath, pr.BaseBranch, err, stderr)
 	}
 
+	prUnit, err := pr.BaseRepo.GetUnit(UnitTypePullRequests)
+	if err != nil {
+		return err
+	}
+	prConfig := prUnit.PullRequestsConfig()
+
+	args := []string{"apply", "--check", "--cached"}
+	if prConfig.IgnoreWhitespaceConflicts {
+		args = append(args, "--ignore-whitespace")
+	}
+	args = append(args, patchPath)
+
 	_, stderr, err = process.GetManager().ExecDirEnv(-1, "", fmt.Sprintf("testPatch (git apply --check): %d", pr.BaseRepo.ID),
 		[]string{"GIT_INDEX_FILE=" + indexTmpPath, "GIT_DIR=" + pr.BaseRepo.RepoPath()},
-		"git", "apply", "--check", "--cached", patchPath)
+		"git", args...)
 	if err != nil {
 		for i := range patchConflicts {
 			if strings.Contains(stderr, patchConflicts[i]) {

models/repo.go

@@ -427,6 +427,11 @@ func (repo *Repository) MustGetUnit(tp UnitType) *RepoUnit {
 			Type:   tp,
 			Config: new(ExternalTrackerConfig),
 		}
+	} else if tp == UnitTypePullRequests {
+		return &RepoUnit{
+			Type:   tp,
+			Config: new(PullRequestsConfig),
+		}
 	}
 	return &RepoUnit{
 		Type:   tp,

models/repo_unit.go

@@ -85,18 +85,44 @@ func (cfg *IssuesConfig) ToDB() ([]byte, error) {
 	return json.Marshal(cfg)
 }
 
+// PullRequestsConfig describes pull requests config
+type PullRequestsConfig struct {
+	IgnoreWhitespaceConflicts bool
+	AllowMerge                bool
+	AllowRebase               bool
+	AllowSquash               bool
+}
+
+// FromDB fills up a PullRequestsConfig from serialized format.
+func (cfg *PullRequestsConfig) FromDB(bs []byte) error {
+	return json.Unmarshal(bs, &cfg)
+}
+
+// ToDB exports a PullRequestsConfig to a serialized format.
+func (cfg *PullRequestsConfig) ToDB() ([]byte, error) {
+	return json.Marshal(cfg)
+}
+
+// IsMergeStyleAllowed returns if merge style is allowed
+func (cfg *PullRequestsConfig) IsMergeStyleAllowed(mergeStyle MergeStyle) bool {
+	return mergeStyle == MergeStyleMerge && cfg.AllowMerge ||
+		mergeStyle == MergeStyleRebase && cfg.AllowRebase ||
+		mergeStyle == MergeStyleSquash && cfg.AllowSquash
+}
+
 // BeforeSet is invoked from XORM before setting the value of a field of this object.
 func (r *RepoUnit) BeforeSet(colName string, val xorm.Cell) {
 	switch colName {
 	case "type":
 		switch UnitType(Cell2Int64(val)) {
-		case UnitTypeCode, UnitTypePullRequests, UnitTypeReleases,
-			UnitTypeWiki:
+		case UnitTypeCode, UnitTypeReleases, UnitTypeWiki:
 			r.Config = new(UnitConfig)
 		case UnitTypeExternalWiki:
 			r.Config = new(ExternalWikiConfig)
 		case UnitTypeExternalTracker:
 			r.Config = new(ExternalTrackerConfig)
+		case UnitTypePullRequests:
+			r.Config = new(PullRequestsConfig)
 		case UnitTypeIssues:
 			r.Config = new(IssuesConfig)
 		default:
@@ -116,8 +142,8 @@ func (r *RepoUnit) CodeConfig() *UnitConfig {
 }
 
 // PullRequestsConfig returns config for UnitTypePullRequests
-func (r *RepoUnit) PullRequestsConfig() *UnitConfig {
-	return r.Config.(*UnitConfig)
+func (r *RepoUnit) PullRequestsConfig() *PullRequestsConfig {
+	return r.Config.(*PullRequestsConfig)
 }
 
 // ReleasesConfig returns config for UnitTypeReleases