Merge branch 'jc/complete-diff-tracked-paths'

'git -C <dir> diff fi<TAB>' did not complete 'file', which has been
corrected.

* jc/complete-diff-tracked-paths:
  completion: 'git diff' completes untracked paths as a last resort
  completion: complete tracked paths for 'git diff'
  completion: no-op refactoring of diff completion

contrib/completion/git-completion.bash

@@ -1947,35 +1947,48 @@ __git_diff_difftool_options="--cached --staged
 
 _git_diff ()
 {
-	__git_has_doubledash && return
+	if ! __git_has_doubledash; then
+		case "$cur" in
+		--diff-algorithm=*)
+			__gitcomp "$__git_diff_algorithms" \
+				"" "${cur##--diff-algorithm=}"
+			return
+			;;
+		--submodule=*)
+			__gitcomp "$__git_diff_submodule_formats" \
+				"" "${cur##--submodule=}"
+			return
+			;;
+		--color-moved=*)
+			__gitcomp "$__git_color_moved_opts" \
+				"" "${cur##--color-moved=}"
+			return
+			;;
+		--color-moved-ws=*)
+			__gitcomp "$__git_color_moved_ws_opts" \
+				"" "${cur##--color-moved-ws=}"
+			return
+			;;
+		--ws-error-highlight=*)
+			__gitcomp "$__git_ws_error_highlight_opts" \
+				"" "${cur##--ws-error-highlight=}"
+			return
+			;;
+		--*)
+			__gitcomp "$__git_diff_difftool_options"
+			return
+			;;
+		esac
+		__git_complete_revlist_file
+	fi
 
-	case "$cur" in
-	--diff-algorithm=*)
-		__gitcomp "$__git_diff_algorithms" "" "${cur##--diff-algorithm=}"
-		return
-		;;
-	--submodule=*)
-		__gitcomp "$__git_diff_submodule_formats" "" "${cur##--submodule=}"
-		return
-		;;
-	--color-moved=*)
-		__gitcomp "$__git_color_moved_opts" "" "${cur##--color-moved=}"
-		return
-		;;
-	--color-moved-ws=*)
-		__gitcomp "$__git_color_moved_ws_opts" "" "${cur##--color-moved-ws=}"
-		return
-		;;
-	--ws-error-highlight=*)
-		__gitcomp "$__git_ws_error_highlight_opts" "" "${cur##--ws-error-highlight=}"
-		return
-		;;
-	--*)
-		__gitcomp "$__git_diff_difftool_options"
-		return
-		;;
-	esac
-	__git_complete_revlist_file
+	if [ ${#COMPREPLY[@]} -eq 0 ]; then
+		__git_complete_index_file ""
+	fi
+
+	if [ ${#COMPREPLY[@]} -eq 0 ]; then
+		__git_complete_index_file "--others --directory"
+	fi
 }
 
 __git_mergetools_common="diffuse diffmerge ecmerge emerge kdiff3 meld opendiff

t/t9902-completion.sh

@@ -2663,6 +2663,8 @@ test_expect_success 'setup for integration tests' '
 	echo content >file1 &&
 	echo more >file2 &&
 	git add file1 file2 &&
+	echo untracked >file3 &&
+	echo untracked >ufile &&
 	git commit -m one &&
 	git branch mybranch &&
 	git tag mytag
@@ -2712,6 +2714,62 @@ test_expect_success 'git -C <path> checkout uses the right repo' '
 	EOF
 '
 
+test_expect_success 'git diff completes tracked paths when no refs match' '
+	# file1 and file2 are tracked but file3 is not
+	# there is no ref that begins with f
+	test_completion "git diff f" <<-\EOF &&
+	file1
+	file2
+	EOF
+	test_completion "git diff -- f" <<-\EOF
+	file1
+	file2
+	EOF
+'
+
+test_expect_success 'git diff [--] completes untracked paths, too' '
+	# ufile is not tracked and there is no ref that begins with u
+	test_completion "git diff u" <<-\EOF &&
+	ufile
+	EOF
+	test_completion "git diff -- u" <<-\EOF
+	ufile
+	EOF
+'
+
+test_expect_success 'git -C <path> diff completes paths in specified repo' '
+	test_when_finished "rm -rf repo-for-diff" &&
+	git init repo-for-diff &&
+	echo content >repo-for-diff/otherfile &&
+	echo content >repo-for-diff/lostfile &&
+	git -C repo-for-diff add otherfile &&
+	git -C repo-for-diff add lostfile &&
+	git -C repo-for-diff commit -m otherfile &&
+	echo untracked >repo-for-diff/oops &&
+	echo untracked >repo-for-diff/ufile &&
+	rm -f repo-for-diff/lostfile &&
+
+	test_completion "git -C repo-for-diff diff o" <<-\EOF &&
+	otherfile
+	EOF
+	test_completion "git -C repo-for-diff diff l" <<-\EOF &&
+	lostfile
+	EOF
+	test_completion "git -C repo-for-diff diff u" <<-\EOF &&
+	ufile
+	EOF
+
+	test_completion "git -C repo-for-diff diff -- o" <<-\EOF &&
+	otherfile
+	EOF
+	test_completion "git -C repo-for-diff diff -- l" <<-\EOF &&
+	lostfile
+	EOF
+	test_completion "git -C repo-for-diff diff -- u" <<-\EOF
+	ufile
+	EOF
+'
+
 test_expect_success 'show completes all refs' '
 	test_completion "git show m" <<-\EOF
 	main Z