Re: [PATCH v2 09/10] read-tree: add "--super-prefix" option, eliminate global

[Glen Choo <chooglen@google.com>]

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> The "--super-prefix" option to "git" was initially added in [1] for
> use with "ls-files"[2], and shortly thereafter "submodule--helper"[3]
> and "grep"[4]. It wasn't until [5] that "read-tree" made use of it.
>
> At the time [5] made sense, but since then we've made "ls-files"
> recurse in-process in [6], "grep" in [7], and finally
> "submodule--helper" in the preceding commits.
>
> Let's also remove it from "read-tree", which allows us to remove the
> option to "git" itself.
>
> We can do this because the only remaining user of it is the submodule
> API, which will now invoke "read-tree" with its new "--super-prefix"
> option. It will only do so when the "submodule_move_head()" function
> is called.
>
> That "submodule_move_head()" function was then only invoked by
> "read-tree" itself, but now rather than setting an environment
> variable to pass "--super-prefix" between cmd_read_tree() we:
>
> - Set a new "super_prefix" in "struct unpack_trees_options". The
>   "super_prefixed()" function in "unpack-trees.c" added in [5] will now
>   use this, rather than get_super_prefix() looking up the environment
>   variable we set earlier in the same process.
>
> - Add the same field to the "struct checkout", which is only needed to
>   ferry the "super_prefix" in the "struct unpack_trees_options" all the
>   way down to the "entry.c" callers of "submodule_move_head()".
>
>   Those calls which used the super prefix all originated in
>   "cmd_read_tree()". The only other caller is the "unlink_entry()"
>   caller in "builtin/checkout.c", which now passes a "NULL".
>
> 1. 74866d75793 (git: make super-prefix option, 2016-10-07)
> 2. e77aa336f11 (ls-files: optionally recurse into submodules, 2016-10-07)
> 3. 89c86265576 (submodule helper: support super prefix, 2016-12-08)
> 4. 0281e487fd9 (grep: optionally recurse into submodules, 2016-12-16)
> 5. 3d415425c7b (unpack-trees: support super-prefix option, 2017-01-17)
> 6. 188dce131fa (ls-files: use repository object, 2017-06-22)
> 7. f9ee2fcdfa0 (grep: recurse in-process using 'struct repository', 2017-08-02)
>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  Documentation/git.txt       |  8 +-------
>  builtin.h                   |  4 ----
>  builtin/checkout.c          |  2 +-
>  builtin/read-tree.c         |  1 +
>  cache.h                     |  2 --
>  entry.c                     | 12 ++++++------
>  entry.h                     |  6 +++++-
>  environment.c               | 13 -------------
>  git.c                       | 37 +++++--------------------------------
>  submodule.c                 | 27 +++++++++------------------
>  submodule.h                 |  5 ++---
>  t/t1001-read-tree-m-2way.sh |  2 +-
>  t/t5616-partial-clone.sh    |  2 +-
>  unpack-trees.c              | 23 +++++++++++++----------
>  unpack-trees.h              |  1 +
>  15 files changed, 46 insertions(+), 99 deletions(-)
>
> diff --git a/Documentation/git.txt b/Documentation/git.txt
> index 1d33e083ab8..f9a7a4554cd 100644
> --- a/Documentation/git.txt
> +++ b/Documentation/git.txt
> @@ -13,8 +13,7 @@ SYNOPSIS
>      [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]
>      [-p|--paginate|-P|--no-pager] [--no-replace-objects] [--bare]
>      [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]
> -    [--super-prefix=<path>] [--config-env=<name>=<envvar>]
> -    <command> [<args>]
> +    [--config-env=<name>=<envvar>] <command> [<args>]
>  
>  DESCRIPTION
>  -----------
> @@ -169,11 +168,6 @@ If you just want to run git as if it was started in `<path>` then use
>  	details.  Equivalent to setting the `GIT_NAMESPACE` environment
>  	variable.
>  
> ---super-prefix=<path>::
> -	Currently for internal use only.  Set a prefix which gives a path from
> -	above a repository down to its root.  One use is to give submodules
> -	context about the superproject that invoked it.
> -
>  --bare::
>  	Treat the repository as a bare repository.  If GIT_DIR
>  	environment is not set, it is set to the current working
> diff --git a/builtin.h b/builtin.h
> index 8901a34d6bf..8264b7e5241 100644
> --- a/builtin.h
> +++ b/builtin.h
> @@ -51,10 +51,6 @@
>   *	on bare repositories.
>   *	This only makes sense when `RUN_SETUP` is also set.
>   *
> - * `SUPPORT_SUPER_PREFIX`:
> - *
> - *	The built-in supports `--super-prefix`.
> - *
>   * `DELAY_PAGER_CONFIG`:
>   *
>   *	If RUN_SETUP or RUN_SETUP_GENTLY is set, git.c normally handles
> diff --git a/builtin/checkout.c b/builtin/checkout.c
> index 2a132392fbe..dc008fb45e8 100644
> --- a/builtin/checkout.c
> +++ b/builtin/checkout.c
> @@ -231,7 +231,7 @@ static int checkout_stage(int stage, const struct cache_entry *ce, int pos,
>  		pos++;
>  	}
>  	if (!overlay_mode) {
> -		unlink_entry(ce);
> +		unlink_entry(ce, NULL);
>  		return 0;
>  	}
>  	if (stage == 2)
> diff --git a/builtin/read-tree.c b/builtin/read-tree.c
> index f4cbe460b97..4b6f22e58c1 100644
> --- a/builtin/read-tree.c
> +++ b/builtin/read-tree.c
> @@ -114,6 +114,7 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
>  	int prefix_set = 0;
>  	struct lock_file lock_file = LOCK_INIT;
>  	const struct option read_tree_options[] = {
> +		OPT__SUPER_PREFIX(&opts.super_prefix),
>  		OPT_CALLBACK_F(0, "index-output", NULL, N_("file"),
>  		  N_("write resulting index to <file>"),
>  		  PARSE_OPT_NONEG, index_output_cb),
> diff --git a/cache.h b/cache.h
> index 26ed03bd6de..a4a0377b800 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -504,7 +504,6 @@ static inline enum object_type object_type(unsigned int mode)
>  #define GIT_NAMESPACE_ENVIRONMENT "GIT_NAMESPACE"
>  #define GIT_WORK_TREE_ENVIRONMENT "GIT_WORK_TREE"
>  #define GIT_PREFIX_ENVIRONMENT "GIT_PREFIX"
> -#define GIT_SUPER_PREFIX_ENVIRONMENT "GIT_INTERNAL_SUPER_PREFIX"
>  #define DEFAULT_GIT_DIR_ENVIRONMENT ".git"
>  #define DB_ENVIRONMENT "GIT_OBJECT_DIRECTORY"
>  #define INDEX_ENVIRONMENT "GIT_INDEX_FILE"
> @@ -590,7 +589,6 @@ int get_common_dir_noenv(struct strbuf *sb, const char *gitdir);
>  int get_common_dir(struct strbuf *sb, const char *gitdir);
>  const char *get_git_namespace(void);
>  const char *strip_namespace(const char *namespaced_ref);
> -const char *get_super_prefix(void);
>  const char *get_git_work_tree(void);
>  
>  /*
> diff --git a/entry.c b/entry.c
> index 616e4f073c1..971ab268714 100644
> --- a/entry.c
> +++ b/entry.c
> @@ -383,7 +383,7 @@ static int write_entry(struct cache_entry *ce, char *path, struct conv_attrs *ca
>  			return error("cannot create submodule directory %s", path);
>  		sub = submodule_from_ce(ce);
>  		if (sub)
> -			return submodule_move_head(ce->name,
> +			return submodule_move_head(ce->name, state->super_prefix,
>  				NULL, oid_to_hex(&ce->oid),
>  				state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
>  		break;
> @@ -476,7 +476,7 @@ int checkout_entry_ca(struct cache_entry *ce, struct conv_attrs *ca,
>  			 * no pathname to return.
>  			 */
>  			BUG("Can't remove entry to a path");
> -		unlink_entry(ce);
> +		unlink_entry(ce, state->super_prefix);
>  		return 0;
>  	}
>  
> @@ -510,10 +510,10 @@ int checkout_entry_ca(struct cache_entry *ce, struct conv_attrs *ca,
>  				if (!(st.st_mode & S_IFDIR))
>  					unlink_or_warn(ce->name);
>  
> -				return submodule_move_head(ce->name,
> +				return submodule_move_head(ce->name, state->super_prefix,
>  					NULL, oid_to_hex(&ce->oid), 0);
>  			} else
> -				return submodule_move_head(ce->name,
> +				return submodule_move_head(ce->name, state->super_prefix,
>  					"HEAD", oid_to_hex(&ce->oid),
>  					state->force ? SUBMODULE_MOVE_HEAD_FORCE : 0);
>  		}
> @@ -560,12 +560,12 @@ int checkout_entry_ca(struct cache_entry *ce, struct conv_attrs *ca,
>  	return write_entry(ce, path.buf, ca, state, 0, nr_checkouts);
>  }
>  
> -void unlink_entry(const struct cache_entry *ce)
> +void unlink_entry(const struct cache_entry *ce, const char *super_prefix)
>  {
>  	const struct submodule *sub = submodule_from_ce(ce);
>  	if (sub) {
>  		/* state.force is set at the caller. */
> -		submodule_move_head(ce->name, "HEAD", NULL,
> +		submodule_move_head(ce->name, super_prefix, "HEAD", NULL,
>  				    SUBMODULE_MOVE_HEAD_FORCE);
>  	}
>  	if (check_leading_path(ce->name, ce_namelen(ce), 1) >= 0)
> diff --git a/entry.h b/entry.h
> index 9be4659881e..2d4fbb88c8f 100644
> --- a/entry.h
> +++ b/entry.h
> @@ -8,6 +8,7 @@ struct checkout {
>  	struct index_state *istate;
>  	const char *base_dir;
>  	int base_dir_len;
> +	const char *super_prefix;
>  	struct delayed_checkout *delayed_checkout;
>  	struct checkout_metadata meta;
>  	unsigned force:1,
> @@ -48,8 +49,11 @@ int finish_delayed_checkout(struct checkout *state, int show_progress);
>  /*
>   * Unlink the last component and schedule the leading directories for
>   * removal, such that empty directories get removed.
> + *
> + * The "super_prefix" is either NULL, or the "--super-prefix" passed
> + * down from "read-tree" et al.
>   */
> -void unlink_entry(const struct cache_entry *ce);
> +void unlink_entry(const struct cache_entry *ce, const char *super_prefix);
>  
>  void *read_blob_entry(const struct cache_entry *ce, size_t *size);
>  int fstat_checkout_output(int fd, const struct checkout *state, struct stat *st);
> diff --git a/environment.c b/environment.c
> index 18d042b467d..1ee3686fd8a 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -102,8 +102,6 @@ char *git_work_tree_cfg;
>  
>  static char *git_namespace;
>  
> -static char *super_prefix;
> -
>  /*
>   * Repository-local GIT_* environment variables; see cache.h for details.
>   */
> @@ -121,7 +119,6 @@ const char * const local_repo_env[] = {
>  	NO_REPLACE_OBJECTS_ENVIRONMENT,
>  	GIT_REPLACE_REF_BASE_ENVIRONMENT,
>  	GIT_PREFIX_ENVIRONMENT,
> -	GIT_SUPER_PREFIX_ENVIRONMENT,
>  	GIT_SHALLOW_FILE_ENVIRONMENT,
>  	GIT_COMMON_DIR_ENVIRONMENT,
>  	NULL
> @@ -234,16 +231,6 @@ const char *strip_namespace(const char *namespaced_ref)
>  	return NULL;
>  }
>  
> -const char *get_super_prefix(void)
> -{
> -	static int initialized;
> -	if (!initialized) {
> -		super_prefix = xstrdup_or_null(getenv(GIT_SUPER_PREFIX_ENVIRONMENT));
> -		initialized = 1;
> -	}
> -	return super_prefix;
> -}
> -
>  static int git_work_tree_initialized;
>  
>  /*
> diff --git a/git.c b/git.c
> index 2bca22cfd9a..00baaf23590 100644
> --- a/git.c
> +++ b/git.c
> @@ -14,9 +14,8 @@
>   * RUN_SETUP for reading from the configuration file.
>   */
>  #define NEED_WORK_TREE		(1<<3)
> -#define SUPPORT_SUPER_PREFIX	(1<<4)
> -#define DELAY_PAGER_CONFIG	(1<<5)
> -#define NO_PARSEOPT		(1<<6) /* parse-options is not used */
> +#define DELAY_PAGER_CONFIG	(1<<4)
> +#define NO_PARSEOPT		(1<<5) /* parse-options is not used */
>  
>  struct cmd_struct {
>  	const char *cmd;
> @@ -29,8 +28,7 @@ const char git_usage_string[] =
>  	   "           [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path]\n"
>  	   "           [-p | --paginate | -P | --no-pager] [--no-replace-objects] [--bare]\n"
>  	   "           [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>]\n"
> -	   "           [--super-prefix=<path>] [--config-env=<name>=<envvar>]\n"
> -	   "           <command> [<args>]");
> +	   "           [--config-env=<name>=<envvar>] <command> [<args>]");
>  
>  const char git_more_info_string[] =
>  	N_("'git help -a' and 'git help -g' list available subcommands and some\n"
> @@ -226,20 +224,6 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>  			setenv(GIT_WORK_TREE_ENVIRONMENT, cmd, 1);
>  			if (envchanged)
>  				*envchanged = 1;
> -		} else if (!strcmp(cmd, "--super-prefix")) {
> -			if (*argc < 2) {
> -				fprintf(stderr, _("no prefix given for --super-prefix\n" ));
> -				usage(git_usage_string);
> -			}
> -			setenv(GIT_SUPER_PREFIX_ENVIRONMENT, (*argv)[1], 1);
> -			if (envchanged)
> -				*envchanged = 1;
> -			(*argv)++;
> -			(*argc)--;
> -		} else if (skip_prefix(cmd, "--super-prefix=", &cmd)) {
> -			setenv(GIT_SUPER_PREFIX_ENVIRONMENT, cmd, 1);
> -			if (envchanged)
> -				*envchanged = 1;
>  		} else if (!strcmp(cmd, "--bare")) {
>  			char *cwd = xgetcwd();
>  			is_bare_repository_cfg = 1;
> @@ -449,11 +433,6 @@ static int run_builtin(struct cmd_struct *p, int argc, const char **argv)
>  		trace_repo_setup(prefix);
>  	commit_pager_choice();
>  
> -	if (!help && get_super_prefix()) {
> -		if (!(p->option & SUPPORT_SUPER_PREFIX))
> -			die(_("%s doesn't support --super-prefix"), p->cmd);
> -	}
> -
>  	if (!help && p->option & NEED_WORK_TREE)
>  		setup_work_tree();
>  
> @@ -504,7 +483,7 @@ static struct cmd_struct commands[] = {
>  	{ "check-ref-format", cmd_check_ref_format, NO_PARSEOPT  },
>  	{ "checkout", cmd_checkout, RUN_SETUP | NEED_WORK_TREE },
>  	{ "checkout--worker", cmd_checkout__worker,
> -		RUN_SETUP | NEED_WORK_TREE | SUPPORT_SUPER_PREFIX },
> +		RUN_SETUP | NEED_WORK_TREE },
>  	{ "checkout-index", cmd_checkout_index,
>  		RUN_SETUP | NEED_WORK_TREE},
>  	{ "cherry", cmd_cherry, RUN_SETUP },
> @@ -583,7 +562,7 @@ static struct cmd_struct commands[] = {
>  	{ "pull", cmd_pull, RUN_SETUP | NEED_WORK_TREE },
>  	{ "push", cmd_push, RUN_SETUP },
>  	{ "range-diff", cmd_range_diff, RUN_SETUP | USE_PAGER },
> -	{ "read-tree", cmd_read_tree, RUN_SETUP | SUPPORT_SUPER_PREFIX},
> +	{ "read-tree", cmd_read_tree, RUN_SETUP },
>  	{ "rebase", cmd_rebase, RUN_SETUP | NEED_WORK_TREE },
>  	{ "receive-pack", cmd_receive_pack },
>  	{ "reflog", cmd_reflog, RUN_SETUP },
> @@ -727,9 +706,6 @@ static void execv_dashed_external(const char **argv)
>  	struct child_process cmd = CHILD_PROCESS_INIT;
>  	int status;
>  
> -	if (get_super_prefix())
> -		die(_("%s doesn't support --super-prefix"), argv[0]);
> -
>  	if (use_pager == -1 && !is_builtin(argv[0]))
>  		use_pager = check_pager_config(argv[0]);
>  	commit_pager_choice();
> @@ -799,9 +775,6 @@ static int run_argv(int *argcp, const char ***argv)
>  			 */
>  			trace2_cmd_name("_run_git_alias_");
>  
> -			if (get_super_prefix())
> -				die("%s doesn't support --super-prefix", **argv);
> -
>  			commit_pager_choice();
>  
>  			strvec_push(&cmd.args, "git");
> diff --git a/submodule.c b/submodule.c
> index d9fd0af81b6..5ac4e1b0568 100644
> --- a/submodule.c
> +++ b/submodule.c
> @@ -2048,14 +2048,6 @@ void submodule_unset_core_worktree(const struct submodule *sub)
>  	strbuf_release(&config_path);
>  }
>  
> -static const char *get_super_prefix_or_empty(void)
> -{
> -	const char *s = get_super_prefix();
> -	if (!s)
> -		s = "";
> -	return s;
> -}
> -
>  static int submodule_has_dirty_index(const struct submodule *sub)
>  {
>  	struct child_process cp = CHILD_PROCESS_INIT;
> @@ -2074,7 +2066,7 @@ static int submodule_has_dirty_index(const struct submodule *sub)
>  	return finish_command(&cp);
>  }
>  
> -static void submodule_reset_index(const char *path)
> +static void submodule_reset_index(const char *path, const char *super_prefix)
>  {
>  	struct child_process cp = CHILD_PROCESS_INIT;
>  	prepare_submodule_repo_env(&cp.env);
> @@ -2083,10 +2075,10 @@ static void submodule_reset_index(const char *path)
>  	cp.no_stdin = 1;
>  	cp.dir = path;
>  
> -	strvec_pushf(&cp.args, "--super-prefix=%s%s/",
> -		     get_super_prefix_or_empty(), path);
>  	/* TODO: determine if this might overwright untracked files */
>  	strvec_pushl(&cp.args, "read-tree", "-u", "--reset", NULL);
> +	strvec_pushf(&cp.args, "--super-prefix=%s%s/",
> +		     (super_prefix ? super_prefix : ""), path);
>  
>  	strvec_push(&cp.args, empty_tree_oid_hex());
>  
> @@ -2099,10 +2091,9 @@ static void submodule_reset_index(const char *path)
>   * For edge cases (a submodule coming into existence or removing a submodule)
>   * pass NULL for old or new respectively.
>   */
> -int submodule_move_head(const char *path,
> -			 const char *old_head,
> -			 const char *new_head,
> -			 unsigned flags)
> +int submodule_move_head(const char *path, const char *super_prefix,
> +			const char *old_head, const char *new_head,
> +			unsigned flags)
>  {
>  	int ret = 0;
>  	struct child_process cp = CHILD_PROCESS_INIT;
> @@ -2148,7 +2139,7 @@ int submodule_move_head(const char *path,
>  			strbuf_release(&gitdir);
>  
>  			/* make sure the index is clean as well */
> -			submodule_reset_index(path);
> +			submodule_reset_index(path, NULL);

Shouldn't we be passing the super prefix? i.e.

  submodule_reset_index(path, super_prefix)

>  		}
>  
>  		if (old_head && (flags & SUBMODULE_MOVE_HEAD_FORCE)) {
> @@ -2166,9 +2157,9 @@ int submodule_move_head(const char *path,
>  	cp.no_stdin = 1;
>  	cp.dir = path;
>  
> -	strvec_pushf(&cp.args, "--super-prefix=%s%s/",
> -		     get_super_prefix_or_empty(), path);
>  	strvec_pushl(&cp.args, "read-tree", "--recurse-submodules", NULL);
> +	strvec_pushf(&cp.args, "--super-prefix=%s%s/",
> +		     (super_prefix ? super_prefix : ""), path);
>  
>  	if (flags & SUBMODULE_MOVE_HEAD_DRY_RUN)
>  		strvec_push(&cp.args, "-n");
> diff --git a/submodule.h b/submodule.h
> index e5ee13fb06a..36a7f7c5b32 100644
> --- a/submodule.h
> +++ b/submodule.h
> @@ -150,9 +150,8 @@ int validate_submodule_git_dir(char *git_dir, const char *submodule_name);
>  
>  #define SUBMODULE_MOVE_HEAD_DRY_RUN (1<<0)
>  #define SUBMODULE_MOVE_HEAD_FORCE   (1<<1)
> -int submodule_move_head(const char *path,
> -			const char *old,
> -			const char *new_head,
> +int submodule_move_head(const char *path, const char *super_prefix,
> +			const char *old_head, const char *new_head,
>  			unsigned flags);
>  
>  void submodule_unset_core_worktree(const struct submodule *sub);
> diff --git a/t/t1001-read-tree-m-2way.sh b/t/t1001-read-tree-m-2way.sh
> index 516a6112fdc..3fb1b0c162d 100755
> --- a/t/t1001-read-tree-m-2way.sh
> +++ b/t/t1001-read-tree-m-2way.sh
> @@ -370,7 +370,7 @@ test_expect_success 'read-tree supports the super-prefix' '
>  	cat <<-EOF >expect &&
>  		error: Updating '\''fictional/a'\'' would lose untracked files in it
>  	EOF
> -	test_must_fail git --super-prefix fictional/ read-tree -u -m "$treeH" "$treeM" 2>actual &&
> +	test_must_fail git read-tree --super-prefix fictional/ -u -m "$treeH" "$treeM" 2>actual &&
>  	test_cmp expect actual
>  '
>  
> diff --git a/t/t5616-partial-clone.sh b/t/t5616-partial-clone.sh
> index e56466580cf..18375bff535 100755
> --- a/t/t5616-partial-clone.sh
> +++ b/t/t5616-partial-clone.sh
> @@ -644,7 +644,7 @@ test_expect_success 'repack does not loosen promisor objects' '
>  	grep "loosen_unused_packed_objects/loosened:0" trace
>  '
>  
> -test_expect_failure 'lazy-fetch in submodule succeeds' '
> +test_expect_success 'lazy-fetch in submodule succeeds' '
>  	# setup
>  	test_config_global protocol.file.allow always &&
>  
> diff --git a/unpack-trees.c b/unpack-trees.c
> index bae812156c4..61c02285454 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -71,7 +71,7 @@ static const char *unpack_plumbing_errors[NB_UNPACK_TREES_WARNING_TYPES] = {
>  	  ? ((o)->msgs[(type)])      \
>  	  : (unpack_plumbing_errors[(type)]) )
>  
> -static const char *super_prefixed(const char *path)
> +static const char *super_prefixed(const char *path, const char *super_prefix)
>  {
>  	/*
>  	 * It is necessary and sufficient to have two static buffers
> @@ -83,7 +83,6 @@ static const char *super_prefixed(const char *path)
>  	static unsigned idx = ARRAY_SIZE(buf) - 1;
>  
>  	if (super_prefix_len < 0) {
> -		const char *super_prefix = get_super_prefix();
>  		if (!super_prefix) {
>  			super_prefix_len = 0;
>  		} else {
> @@ -236,7 +235,8 @@ static int add_rejected_path(struct unpack_trees_options *o,
>  		return -1;
>  
>  	if (!o->show_all_errors)
> -		return error(ERRORMSG(o, e), super_prefixed(path));
> +		return error(ERRORMSG(o, e), super_prefixed(path,
> +							    o->super_prefix));
>  
>  	/*
>  	 * Otherwise, insert in a list for future display by
> @@ -263,7 +263,8 @@ static void display_error_msgs(struct unpack_trees_options *o)
>  			error_displayed = 1;
>  			for (i = 0; i < rejects->nr; i++)
>  				strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
> -			error(ERRORMSG(o, e), super_prefixed(path.buf));
> +			error(ERRORMSG(o, e), super_prefixed(path.buf,
> +							     o->super_prefix));
>  			strbuf_release(&path);
>  		}
>  		string_list_clear(rejects, 0);
> @@ -290,7 +291,8 @@ static void display_warning_msgs(struct unpack_trees_options *o)
>  			warning_displayed = 1;
>  			for (i = 0; i < rejects->nr; i++)
>  				strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
> -			warning(ERRORMSG(o, e), super_prefixed(path.buf));
> +			warning(ERRORMSG(o, e), super_prefixed(path.buf,
> +							       o->super_prefix));
>  			strbuf_release(&path);
>  		}
>  		string_list_clear(rejects, 0);
> @@ -312,7 +314,7 @@ static int check_submodule_move_head(const struct cache_entry *ce,
>  	if (o->reset)
>  		flags |= SUBMODULE_MOVE_HEAD_FORCE;
>  
> -	if (submodule_move_head(ce->name, old_id, new_id, flags))
> +	if (submodule_move_head(ce->name, NULL, old_id, new_id, flags))

Similarly, shouldn't this be

  - submodule_move_head(ce->name, NULL, old_id, new_id, flags)
  + submodule_move_head(ce->name, o->super_prefix, old_id, new_id, flags)

>  		return add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
>  	return 0;
>  }
> @@ -415,6 +417,7 @@ static int check_updates(struct unpack_trees_options *o,
>  	int i, pc_workers, pc_threshold;
>  
>  	trace_performance_enter();
> +	state.super_prefix = o->super_prefix;
>  	state.force = 1;
>  	state.quiet = 1;
>  	state.refresh_cache = 1;
> @@ -445,7 +448,7 @@ static int check_updates(struct unpack_trees_options *o,
>  
>  		if (ce->ce_flags & CE_WT_REMOVE) {
>  			display_progress(progress, ++cnt);
> -			unlink_entry(ce);
> +			unlink_entry(ce, o->super_prefix);
>  		}
>  	}
>  
> @@ -2958,8 +2961,8 @@ int bind_merge(const struct cache_entry * const *src,
>  	if (a && old)
>  		return o->quiet ? -1 :
>  			error(ERRORMSG(o, ERROR_BIND_OVERLAP),
> -			      super_prefixed(a->name),
> -			      super_prefixed(old->name));
> +			      super_prefixed(a->name, o->super_prefix),
> +			      super_prefixed(old->name, o->super_prefix));
>  	if (!a)
>  		return keep_entry(old, o);
>  	else
> @@ -3020,7 +3023,7 @@ int stash_worktree_untracked_merge(const struct cache_entry * const *src,
>  
>  	if (worktree && untracked)
>  		return error(_("worktree and untracked commit have duplicate entries: %s"),
> -			     super_prefixed(worktree->name));
> +			     super_prefixed(worktree->name, o->super_prefix));
>  
>  	return merged_entry(worktree ? worktree : untracked, NULL, o);
>  }
> diff --git a/unpack-trees.h b/unpack-trees.h
> index efb9edfbb27..9b81e284073 100644
> --- a/unpack-trees.h
> +++ b/unpack-trees.h
> @@ -74,6 +74,7 @@ struct unpack_trees_options {
>  		     dry_run;
>  	enum unpack_trees_reset_type reset;
>  	const char *prefix;
> +	const char *super_prefix;
>  	int cache_bottom;
>  	struct pathspec *pathspec;
>  	merge_fn_t fn;
> -- 
> 2.38.0.1471.ge4d8947e7aa