feat: Allow the fixup helper to return commits on the main branch with a warning.

pkg/gui/controllers/helpers/fixup_helper.go

@@ -104,12 +104,33 @@ func (self *FixupHelper) HandleFindBaseCommitForFixupPress() error {
 	}
 
 	if len(hashGroups[NOT_MERGED]) == 0 {
-		// If all the commits are merged, show the "already on main branch"
-		// error. It isn't worth doing a detailed report of which commits we
-		// found.
-		return errors.New(self.c.Tr.BaseCommitIsAlreadyOnMainBranch)
-	}
+		// The commit is already merged, but we attempt to show it anyway.
+		if len(hashGroups[MERGED]) > 1 {
+			// We found multiple merged commits. List them in error message
+			subjects := self.getHashesAndSubjects(commits, hashGroups[NOT_MERGED])
+			message := self.c.Tr.MultipleBaseCommitsFoundMerged
+			return fmt.Errorf("%s\n\n%s", message, subjects)
+		} else if len(hashGroups[MERGED]) == 0 {
+			// This can not happen, as the commit has to be either in
+			// CANNOT_TELL, NOT_MERGED or MERGED state and we already established,
+			// that it is not in CANNOT_TELL or NOT_MERGED
+			return errors.New(self.c.Tr.BaseCommitIsNotInCurrentView)
+		}
 
+		// At this point we know that the MERGED bucket has exactly one commit,
+		// and that's the one we want to select.
+		_, index, found := self.findCommit(commits, hashGroups[MERGED][0])
+		if !found {
+			// However the commit is not in view, so we cannot select it.
+			return errors.New(self.c.Tr.BaseCommitIsNotInCurrentView)
+		}
+		// We found the commit, so we show it with a warning message, that it is already merged.
+		return self.c.ConfirmIf(true, types.ConfirmOpts{
+			Title:         self.c.Tr.FindBaseCommitForFixup,
+			Prompt:        self.c.Tr.BaseCommitIsAlreadyOnMainBranch,
+			HandleConfirm: self.getHandlerToStageAndSelectIndex(hasStagedChanges, index),
+		})
+	}
 	if len(hashGroups[NOT_MERGED]) > 1 {
 		// If there are multiple commits that could be the base commit, list
 		// them in the error message. But only the candidates from the current
@@ -126,22 +147,26 @@ func (self *FixupHelper) HandleFindBaseCommitForFixupPress() error {
 	_, index, _ := self.findCommit(commits, hashGroups[NOT_MERGED][0])
 
 	return self.c.ConfirmIf(warnAboutAddedLines, types.ConfirmOpts{
-		Title:  self.c.Tr.FindBaseCommitForFixup,
-		Prompt: self.c.Tr.HunksWithOnlyAddedLinesWarning,
-		HandleConfirm: func() error {
-			if !hasStagedChanges {
-				if err := self.c.Git().WorkingTree.StageAll(true); err != nil {
-					return err
-				}
-				self.c.Refresh(types.RefreshOptions{Mode: types.SYNC, Scope: []types.RefreshableView{types.FILES}})
+		Title:         self.c.Tr.FindBaseCommitForFixup,
+		Prompt:        self.c.Tr.HunksWithOnlyAddedLinesWarning,
+		HandleConfirm: self.getHandlerToStageAndSelectIndex(hasStagedChanges, index),
+	})
+}
+
+func (self *FixupHelper) getHandlerToStageAndSelectIndex(hasStagedChanges bool, index int) func() error {
+	return func() error {
+		if !hasStagedChanges {
+			if err := self.c.Git().WorkingTree.StageAll(true); err != nil {
+				return err
 			}
+			self.c.Refresh(types.RefreshOptions{Mode: types.SYNC, Scope: []types.RefreshableView{types.FILES}})
+		}
 
-			self.c.Contexts().LocalCommits.SetSelection(index)
-			self.c.Contexts().LocalCommits.FocusLine(true)
-			self.c.Context().Push(self.c.Contexts().LocalCommits, types.OnFocusOpts{})
-			return nil
-		},
-	})
+		self.c.Contexts().LocalCommits.SetSelection(index)
+		self.c.Contexts().LocalCommits.FocusLine(true)
+		self.c.Context().Push(self.c.Contexts().LocalCommits, types.OnFocusOpts{})
+		return nil
+	}
 }
 
 func (self *FixupHelper) getHashesAndSubjects(commits []*models.Commit, hashes []string) string {

pkg/i18n/english.go

@@ -45,6 +45,7 @@ type TranslationSet struct {
 	NoBaseCommitsFound                    string
 	MultipleBaseCommitsFoundStaged        string
 	MultipleBaseCommitsFoundUnstaged      string
+	MultipleBaseCommitsFoundMerged        string
 	BaseCommitIsAlreadyOnMainBranch       string
 	BaseCommitIsNotInCurrentView          string
 	HunksWithOnlyAddedLinesWarning        string
@@ -1140,6 +1141,7 @@ func EnglishTranslationSet() *TranslationSet {
 		NoBaseCommitsFound:                   "No base commits found",
 		MultipleBaseCommitsFoundStaged:       "Multiple base commits found. (Try staging fewer changes at once)",
 		MultipleBaseCommitsFoundUnstaged:     "Multiple base commits found. (Try staging some of the changes)",
+		MultipleBaseCommitsFoundMerged:       "Multiple base commits found, that are already on the main branch. (Try staging some of the changes)",
 		BaseCommitIsAlreadyOnMainBranch:      "The base commit for this change is already on the main branch",
 		BaseCommitIsNotInCurrentView:         "Base commit is not in current view",
 		HunksWithOnlyAddedLinesWarning:       "There are ranges of only added lines in the diff; be careful to check that these belong in the found base commit.\n\nProceed?",

pkg/integration/tests/commit/find_base_commit_for_fixup_in_main_branch.go

@@ -0,0 +1,51 @@
+package commit
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var FindBaseCommitForFixupInMainBranch = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Finds the base commit to create a fixup for when the commit is already merged into master",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.
+			EmptyCommit("1st commit").
+			CreateFileAndAdd("file1", "file1 content\n").
+			Commit("2nd commit").
+			NewBranch("mybranch").
+			CreateFileAndAdd("file2", "file2 content\n").
+			Commit("3rd commit").
+			EmptyCommit("4th commit").
+			UpdateFile("file1", "file1 changed content")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Lines(
+				Contains("4th commit").IsSelected(),
+				Contains("3rd commit"),
+				Contains("2nd commit"),
+				Contains("1st commit"),
+			)
+
+		t.Views().Files().
+			Focus().
+			Press(keys.Files.FindBaseCommitForFixup)
+		t.ExpectPopup().
+			Confirmation().
+			Title(Equals("Find base commit for fixup")).
+			Content(Contains("already on the main branch")).
+			Confirm()
+
+		t.Views().Commits().
+			IsFocused().
+			Lines(
+				Contains("4th commit"),
+				Contains("3rd commit"),
+				Contains("2nd commit").IsSelected(),
+				Contains("1st commit"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -131,6 +131,7 @@ var tests = []*components.IntegrationTest{
 	commit.FailHooksThenCommitNoHooks,
 	commit.FindBaseCommitForFixup,
 	commit.FindBaseCommitForFixupDisregardMainBranch,
+	commit.FindBaseCommitForFixupInMainBranch,
 	commit.FindBaseCommitForFixupOnlyAddedLines,
 	commit.FindBaseCommitForFixupWarningForAddedLines,
 	commit.Highlight,