Make opening git difftool more consistent

The default shortcut to open git difftool (ctrl+t) is not available on
the "Local Branches" window. It is available when selecting a commit
from a local branch, a remote branch, or a tag from the "Local Branches"
window.

This is inconsistent since branches or tags are also commits, the
shortcut should also work on them directly.

This commit remedies this inconsistency by allowing the use of the
shortcut directly on a branch or a tag. The shortcut works both in the
"standard" mode and the "diffing" mode.

pkg/gui/controllers/branches_controller.go

@@ -158,6 +158,14 @@ func (self *BranchesController) GetKeybindings(opts types.KeybindingsOpts) []*ty
 			OpensMenu:         true,
 			DisplayOnScreen:   true,
 		},
+		{
+			Key: opts.GetKey(opts.Config.Universal.OpenDiffTool),
+			Handler: self.withItem(func(selectedBranch *models.Branch) error {
+				return self.c.Helpers().Diff.DefaultOpenDiffTool(selectedBranch)
+			}),
+			GetDisabledReason: self.require(self.singleItemSelected()),
+			Description:       self.c.Tr.OpenDiffTool,
+		},
 	}
 }
 

pkg/gui/controllers/helpers/diff_helper.go

@@ -1,6 +1,7 @@
 package helpers
 
 import (
+	"github.com/jesseduffield/lazygit/pkg/commands/git_commands"
 	"github.com/jesseduffield/lazygit/pkg/gui/context"
 	"github.com/jesseduffield/lazygit/pkg/gui/modes/diffing"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
@@ -119,3 +120,18 @@ func (self *DiffHelper) IgnoringWhitespaceSubTitle() string {
 
 	return ""
 }
+
+func (self *DiffHelper) DefaultOpenDiffTool(selectedRef types.Ref) error {
+	to := selectedRef.RefName()
+	from, reverse := self.c.Modes().Diffing.GetFromAndReverseArgsForDiff(selectedRef.ParentRefName())
+	_, err := self.c.RunSubprocess(self.c.Git().Diff.OpenDiffToolCmdObj(
+		git_commands.DiffToolCmdOptions{
+			Filepath:    ".",
+			FromCommit:  from,
+			ToCommit:    to,
+			Reverse:     reverse,
+			IsDirectory: true,
+			Staged:      false,
+		}))
+	return err
+}

pkg/gui/controllers/remote_branches_controller.go

@@ -94,6 +94,14 @@ func (self *RemoteBranchesController) GetKeybindings(opts types.KeybindingsOpts)
 			Tooltip:           self.c.Tr.ResetTooltip,
 			OpensMenu:         true,
 		},
+		{
+			Key: opts.GetKey(opts.Config.Universal.OpenDiffTool),
+			Handler: self.withItem(func(selectedBranch *models.RemoteBranch) error {
+				return self.c.Helpers().Diff.DefaultOpenDiffTool(selectedBranch)
+			}),
+			GetDisabledReason: self.require(self.singleItemSelected()),
+			Description:       self.c.Tr.OpenDiffTool,
+		},
 	}
 }
 

pkg/gui/controllers/tags_controller.go

@@ -74,6 +74,14 @@ func (self *TagsController) GetKeybindings(opts types.KeybindingsOpts) []*types.
 			DisplayOnScreen:   true,
 			OpensMenu:         true,
 		},
+		{
+			Key: opts.GetKey(opts.Config.Universal.OpenDiffTool),
+			Handler: self.withItem(func(selectedTag *models.Tag) error {
+				return self.c.Helpers().Diff.DefaultOpenDiffTool(selectedTag)
+			}),
+			GetDisabledReason: self.require(self.singleItemSelected()),
+			Description:       self.c.Tr.OpenDiffTool,
+		},
 	}
 
 	return bindings