Fix some problems with patches if git diff was customized with config (e.g. external or noprefix). (#3222)

- **PR Description**

I encountered the problem that I couldn't extract changes into a new
commit because I had difftastic as an external git tool configured.

Add `diff.noprefix=false` config Option and also specify `--no-ext-diff`
when doing the `git diff` after applying a patch.
This fixes #3107.
Though, there might be other config options that can cause problems, but
fixing these common cases should be an improvement nevertheless.

pkg/commands/git_commands/commit.go

@@ -239,6 +239,7 @@ func (self *CommitCommands) ShowCmdObj(sha string, filterPath string) oscommands
 
 	extDiffCmd := self.UserConfig.Git.Paging.ExternalDiffCommand
 	cmdArgs := NewGitCmd("show").
+		Config("diff.noprefix=false").
 		ConfigIf(extDiffCmd != "", "diff.external="+extDiffCmd).
 		ArgIfElse(extDiffCmd != "", "--ext-diff", "--no-ext-diff").
 		Arg("--submodule").

pkg/commands/git_commands/commit_file_loader.go

@@ -24,6 +24,7 @@ func NewCommitFileLoader(common *common.Common, cmd oscommands.ICmdObjBuilder) *
 // GetFilesInDiff get the specified commit files
 func (self *CommitFileLoader) GetFilesInDiff(from string, to string, reverse bool) ([]*models.CommitFile, error) {
 	cmdArgs := NewGitCmd("diff").
+		Config("diff.noprefix=false").
 		Arg("--submodule").
 		Arg("--no-ext-diff").
 		Arg("--name-status").

pkg/commands/git_commands/commit_test.go

@@ -197,7 +197,7 @@ func TestCommitShowCmdObj(t *testing.T) {
 			contextSize:      3,
 			ignoreWhitespace: false,
 			extDiffCmd:       "",
-			expected:         []string{"-C", "/path/to/worktree", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890"},
+			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890"},
 		},
 		{
 			testName:         "Default case with filter path",
@@ -205,7 +205,7 @@ func TestCommitShowCmdObj(t *testing.T) {
 			contextSize:      3,
 			ignoreWhitespace: false,
 			extDiffCmd:       "",
-			expected:         []string{"-C", "/path/to/worktree", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890", "--", "file.txt"},
+			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890", "--", "file.txt"},
 		},
 		{
 			testName:         "Show diff with custom context size",
@@ -213,7 +213,7 @@ func TestCommitShowCmdObj(t *testing.T) {
 			contextSize:      77,
 			ignoreWhitespace: false,
 			extDiffCmd:       "",
-			expected:         []string{"-C", "/path/to/worktree", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=77", "--stat", "--decorate", "-p", "1234567890"},
+			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=77", "--stat", "--decorate", "-p", "1234567890"},
 		},
 		{
 			testName:         "Show diff, ignoring whitespace",
@@ -221,7 +221,7 @@ func TestCommitShowCmdObj(t *testing.T) {
 			contextSize:      77,
 			ignoreWhitespace: true,
 			extDiffCmd:       "",
-			expected:         []string{"-C", "/path/to/worktree", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=77", "--stat", "--decorate", "-p", "1234567890", "--ignore-all-space"},
+			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "show", "--no-ext-diff", "--submodule", "--color=always", "--unified=77", "--stat", "--decorate", "-p", "1234567890", "--ignore-all-space"},
 		},
 		{
 			testName:         "Show diff with external diff command",
@@ -229,7 +229,7 @@ func TestCommitShowCmdObj(t *testing.T) {
 			contextSize:      3,
 			ignoreWhitespace: false,
 			extDiffCmd:       "difft --color=always",
-			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.external=difft --color=always", "show", "--ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890"},
+			expected:         []string{"-C", "/path/to/worktree", "-c", "diff.external=difft --color=always", "-c", "diff.noprefix=false", "show", "--ext-diff", "--submodule", "--color=always", "--unified=3", "--stat", "--decorate", "-p", "1234567890"},
 		},
 	}
 

pkg/commands/git_commands/diff.go

@@ -15,6 +15,7 @@ func NewDiffCommands(gitCommon *GitCommon) *DiffCommands {
 func (self *DiffCommands) DiffCmdObj(diffArgs []string) oscommands.ICmdObj {
 	return self.cmd.New(
 		NewGitCmd("diff").
+			Config("diff.noprefix=false").
 			Arg("--submodule", "--no-ext-diff", "--color").
 			Arg(diffArgs...).
 			Dir(self.repoPaths.worktreePath).
@@ -24,6 +25,7 @@ func (self *DiffCommands) DiffCmdObj(diffArgs []string) oscommands.ICmdObj {
 
 func (self *DiffCommands) internalDiffCmdObj(diffArgs ...string) *GitCommandBuilder {
 	return NewGitCmd("diff").
+		Config("diff.noprefix=false").
 		Arg("--no-ext-diff", "--no-color").
 		Arg(diffArgs...).
 		Dir(self.repoPaths.worktreePath)
@@ -87,6 +89,7 @@ func (self *DiffCommands) OpenDiffToolCmdObj(opts DiffToolCmdOptions) oscommands
 func (self *DiffCommands) DiffIndexCmdObj(diffArgs ...string) oscommands.ICmdObj {
 	return self.cmd.New(
 		NewGitCmd("diff-index").
+			Config("diff.noprefix=false").
 			Arg("--submodule", "--no-ext-diff", "--no-color", "--patch").
 			Arg(diffArgs...).ToArgv(),
 	)

pkg/commands/git_commands/patch.go

@@ -321,7 +321,11 @@ func (self *PatchCommands) PullPatchIntoNewCommit(
 // only some lines of a range of adjacent added lines. To solve this, we
 // get the diff of HEAD and the original commit and then apply that.
 func (self *PatchCommands) diffHeadAgainstCommit(commit *models.Commit) (string, error) {
-	cmdArgs := NewGitCmd("diff").Arg("HEAD.." + commit.Sha).ToArgv()
+	cmdArgs := NewGitCmd("diff").
+		Config("diff.noprefix=false").
+		Arg("--no-ext-diff").
+		Arg("HEAD.." + commit.Sha).
+		ToArgv()
 
 	return self.cmd.New(cmdArgs).RunWithOutput()
 }

pkg/commands/git_commands/working_tree.go

@@ -291,6 +291,7 @@ func (self *WorkingTreeCommands) ShowFileDiffCmdObj(from string, to string, reve
 	useExtDiff := extDiffCmd != "" && !plain
 
 	cmdArgs := NewGitCmd("diff").
+		Config("diff.noprefix=false").
 		ConfigIf(useExtDiff, "diff.external="+extDiffCmd).
 		ArgIfElse(useExtDiff, "--ext-diff", "--no-ext-diff").
 		Arg("--submodule").

pkg/commands/git_commands/working_tree_test.go

@@ -348,7 +348,7 @@ func TestWorkingTreeShowFileDiff(t *testing.T) {
 			ignoreWhitespace: false,
 			contextSize:      3,
 			runner: oscommands.NewFakeRunner(t).
-				ExpectGitArgs([]string{"-C", "/path/to/worktree", "diff", "--no-ext-diff", "--submodule", "--unified=3", "--no-renames", "--color=always", "1234567890", "0987654321", "--", "test.txt"}, expectedResult, nil),
+				ExpectGitArgs([]string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "diff", "--no-ext-diff", "--submodule", "--unified=3", "--no-renames", "--color=always", "1234567890", "0987654321", "--", "test.txt"}, expectedResult, nil),
 		},
 		{
 			testName:         "Show diff with custom context size",
@@ -359,7 +359,7 @@ func TestWorkingTreeShowFileDiff(t *testing.T) {
 			ignoreWhitespace: false,
 			contextSize:      123,
 			runner: oscommands.NewFakeRunner(t).
-				ExpectGitArgs([]string{"-C", "/path/to/worktree", "diff", "--no-ext-diff", "--submodule", "--unified=123", "--no-renames", "--color=always", "1234567890", "0987654321", "--", "test.txt"}, expectedResult, nil),
+				ExpectGitArgs([]string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "diff", "--no-ext-diff", "--submodule", "--unified=123", "--no-renames", "--color=always", "1234567890", "0987654321", "--", "test.txt"}, expectedResult, nil),
 		},
 		{
 			testName:         "Default case (ignore whitespace)",
@@ -370,7 +370,7 @@ func TestWorkingTreeShowFileDiff(t *testing.T) {
 			ignoreWhitespace: true,
 			contextSize:      3,
 			runner: oscommands.NewFakeRunner(t).
-				ExpectGitArgs([]string{"-C", "/path/to/worktree", "diff", "--no-ext-diff", "--submodule", "--unified=3", "--no-renames", "--color=always", "1234567890", "0987654321", "--ignore-all-space", "--", "test.txt"}, expectedResult, nil),
+				ExpectGitArgs([]string{"-C", "/path/to/worktree", "-c", "diff.noprefix=false", "diff", "--no-ext-diff", "--submodule", "--unified=3", "--no-renames", "--color=always", "1234567890", "0987654321", "--ignore-all-space", "--", "test.txt"}, expectedResult, nil),
 		},
 	}
 

pkg/integration/tests/patch_building/move_to_index_works_even_if_noprefix_is_set.go

@@ -0,0 +1,50 @@
+package patch_building
+
+import (
+	"github.com/jesseduffield/lazygit/pkg/config"
+	. "github.com/jesseduffield/lazygit/pkg/integration/components"
+)
+
+var MoveToIndexWorksEvenIfNoprefixIsSet = NewIntegrationTest(NewIntegrationTestArgs{
+	Description:  "Moving a patch to the index works even if diff.noprefix or diff.external are set",
+	ExtraCmdArgs: []string{},
+	Skip:         false,
+	SetupConfig:  func(config *config.AppConfig) {},
+	SetupRepo: func(shell *Shell) {
+		shell.CreateFileAndAdd("file1", "file1 content\n")
+		shell.Commit("first commit")
+
+		// Test that this works even if custom diff options are set
+		shell.SetConfig("diff.noprefix", "true")
+		shell.SetConfig("diff.external", "echo")
+	},
+	Run: func(t *TestDriver, keys config.KeybindingConfig) {
+		t.Views().Commits().
+			Focus().
+			Lines(
+				Contains("first commit").IsSelected(),
+			).
+			PressEnter()
+
+		t.Views().CommitFiles().
+			IsFocused().
+			Lines(
+				Contains("file1").IsSelected(),
+			).
+			PressPrimaryAction()
+
+		t.Views().PatchBuildingSecondary().Content(Contains("+file1 content"))
+
+		t.Common().SelectPatchOption(Contains("Move patch out into index"))
+
+		t.Views().CommitFiles().IsFocused().
+			Lines(
+				Equals("(none)"),
+			)
+
+		t.Views().Files().
+			Lines(
+				Contains("A").Contains("file1"),
+			)
+	},
+})

pkg/integration/tests/test_list.go

@@ -204,6 +204,7 @@ var tests = []*components.IntegrationTest{
 	patch_building.MoveToIndexPartOfAdjacentAddedLines,
 	patch_building.MoveToIndexPartial,
 	patch_building.MoveToIndexWithConflict,
+	patch_building.MoveToIndexWorksEvenIfNoprefixIsSet,
 	patch_building.MoveToLaterCommit,
 	patch_building.MoveToLaterCommitPartialHunk,
 	patch_building.MoveToNewCommit,