Merge branch 'vm/complete-history' into seen

The command line completion (in contrib/) has been taught to handle
the experimental 'git history' command.

* vm/complete-history:
  completion: complete 'git history split' pathspecs
  completion: complete 'git history --update-refs' values
  completion: complete 'git history --empty' values
  completion: add 'git history' subcommands

contrib/completion/git-completion.bash

@@ -2157,6 +2157,74 @@ _git_help ()
 	fi
 }
 
+__git_history_has_revision ()
+{
+	local i
+
+	for ((i = __git_cmd_idx + 2; i < cword; i++)); do
+		case "${words[i]}" in
+		--empty|--update-refs)
+			((i++))
+			;;
+		-*)
+			;;
+		*)
+			return 0
+			;;
+		esac
+	done
+	return 1
+}
+
+_git_history ()
+{
+	local subcommands subcommand
+
+	__git_resolve_builtins "history"
+
+	subcommands="$___git_resolved_builtins"
+	subcommand="$(__git_find_subcommand "$subcommands")"
+
+	if [ -z "$subcommand" ]; then
+		__gitcomp "$subcommands"
+		return
+	fi
+
+	if ! __git_has_doubledash; then
+		case "$prev,$cur" in
+		--empty,*|*,--empty=*)
+			case "$subcommand" in
+			drop|fixup)
+				__gitcomp "drop keep abort" "" \
+					"${cur##--empty=}"
+				return
+				;;
+			esac
+			;;
+		--update-refs,*|*,--update-refs=*)
+			__gitcomp "branches head" "" \
+				"${cur##--update-refs=}"
+			return
+			;;
+		*,--*)
+			__gitcomp_builtin "history_$subcommand"
+			return
+			;;
+		esac
+	fi
+
+	if ! __git_history_has_revision; then
+		__git_complete_refs
+		return
+	fi
+
+	case "$subcommand" in
+	split)
+		__git_complete_index_file "--cached"
+		;;
+	esac
+}
+
 _git_init ()
 {
 	case "$cur" in

t/t9902-completion.sh

@@ -3167,6 +3167,56 @@ test_expect_success 'git clone --config= - value' '
 	EOF
 '
 
+test_expect_success 'git history subcommands' '
+	test_completion "git history " <<-\EOF
+	drop Z
+	fixup Z
+	reword Z
+	split Z
+	squash Z
+	EOF
+'
+
+test_expect_success 'git history subcommand options' '
+	test_completion "git history split main --" <<-\EOF &&
+	--update-refs=Z
+	--dry-run Z
+	--no-dry-run Z
+	EOF
+	test_completion "git history fixup --upd" "--update-refs=" &&
+	test_completion "git history fixup --ree" "--reedit-message " &&
+	test_completion "git history split --upd" "--update-refs=" &&
+	test_completion "git history split main --dry" "--dry-run " &&
+	test_completion "git history reword main -- --d" "" &&
+	test_completion "git history fixup --empty=ke" "keep " &&
+	test_completion "git history drop --empty ab" "abort " &&
+	test_completion "git history reword --empty=ke" "" &&
+	test_completion "git history fixup --update-refs=he" "head " &&
+	test_completion "git history split --update-refs he" "head " &&
+	test_completion "git history reword main -- --update-refs=he" "" &&
+	test_completion "git history reword main -- --update-refs he" ""
+'
+
+test_expect_success 'git history revisions' '
+	test_completion "git history split ma" "main " &&
+	test_completion "git history split --update-refs head ma" "main " &&
+	test_completion "git history fixup --empty drop ma" "main " &&
+	test_completion "git history reword main m" ""
+'
+
+test_expect_success 'git history split pathspecs' '
+	test_completion "git history split main -- --update-refs=h" "" &&
+	test_completion "git history split main -- --update-refs h" "" &&
+	test_completion "git history split --dry-run main file" <<-\EOF &&
+	file1Z
+	file2Z
+	EOF
+	test_completion "git history split main -- file" <<-\EOF
+	file1Z
+	file2Z
+	EOF
+'
+
 test_expect_success 'git reflog show' '
 	test_when_finished "git checkout - && git branch -d shown" &&
 	git checkout -b shown &&