read-tree: add "--super-prefix" option, eliminate global

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 32 deletions

diff --git a/git.c b/git.c
index 2c31ba2704..32a5be68a1 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");