sparse-index: enforce declaration and convert mv

builtin/am.c

@@ -23,6 +23,7 @@
 #include "lockfile.h"
 #include "cache-tree.h"
 #include "refs.h"
+#include "repo-settings.h"
 #include "commit.h"
 #include "diff.h"
 #include "unpack-trees.h"
@@ -2464,6 +2465,9 @@ int cmd_am(int argc,
 	/* Ensure a valid committer ident can be constructed */
 	git_committer_info(IDENT_STRICT);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 1;
+
 	if (repo_read_index_preload(the_repository, NULL, 0) < 0)
 		die(_("failed to read the index"));
 

builtin/grep.c

@@ -500,6 +500,10 @@ static int grep_submodule(struct grep_opt *opt,
 	 *
 	 * Note that this list is not exhaustive.
 	 */
+	/* not yet verified whether subrepo can use the sparse index */
+	prepare_repo_settings(subrepo);
+	subrepo->settings.command_requires_full_index = 1;
+
 	repo_read_gitmodules(subrepo, 0);
 
 	/*

builtin/mv.c

@@ -22,11 +22,13 @@
 #include "string-list.h"
 #include "parse-options.h"
 #include "read-cache-ll.h"
+#include "repo-settings.h"
 
 #include "setup.h"
 #include "strvec.h"
 #include "submodule.h"
 #include "entry.h"
+#include "sparse-index.h"
 
 static const char * const builtin_mv_usage[] = {
 	N_("git mv [-v] [-f] [-n] [-k] <source> <destination>"),
@@ -152,7 +154,11 @@ static int empty_dir_has_sparse_contents(const char *name)
 	int pos = index_name_pos(the_repository->index, with_slash, length);
 	const struct cache_entry *ce;
 
-	if (pos < 0) {
+	if (pos >= 0) {
+		ce = the_repository->index->cache[pos];
+		if (S_ISSPARSEDIR(ce->ce_mode))
+			ret = 1;
+	} else {
 		pos = -pos - 1;
 		if (pos >= the_repository->index->cache_nr)
 			goto free_return;
@@ -247,10 +253,16 @@ int cmd_mv(int argc,
 	if (--argc < 1)
 		usage_with_options(builtin_mv_usage, builtin_mv_options);
 
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 0;
+
 	repo_hold_locked_index(the_repository, &lock_file, LOCK_DIE_ON_ERROR);
 	if (repo_read_index(the_repository) < 0)
 		die(_("index file corrupt"));
 
+	if (ignore_sparse)
+		ensure_full_index(the_repository->index);
+
 	internal_prefix_pathspec(&sources, prefix, argv, argc, 0);
 	CALLOC_ARRAY(modes, argc);
 
@@ -313,6 +325,10 @@ int cmd_mv(int argc,
 				if (!path_in_sparse_checkout(src_w_slash, the_repository->index) &&
 				    empty_dir_has_sparse_contents(src)) {
 					free(src_w_slash);
+					if (!ignore_sparse) {
+						string_list_append(&only_match_skip_worktree, src);
+						goto act_on_entry;
+					}
 					modes[i] |= SKIP_WORKTREE_DIR;
 					goto dir_check;
 				}

builtin/submodule--helper.c

@@ -16,6 +16,7 @@
 #include "read-cache.h"
 #include "setup.h"
 #include "sparse-index.h"
+#include "repo-settings.h"
 #include "submodule.h"
 #include "submodule-config.h"
 #include "string-list.h"
@@ -3832,5 +3833,9 @@ int cmd_submodule__helper(int argc,
 	};
 	argc = parse_options(argc, argv, prefix, options, usage, 0);
 
+	/* not yet verified whether this can use the sparse index */
+	prepare_repo_settings(the_repository);
+	the_repository->settings.command_requires_full_index = 1;
+
 	return fn(argc, argv, prefix, repo);
 }

read-cache.c

@@ -2189,7 +2189,7 @@ static void set_new_index_sparsity(struct index_state *istate)
 	 * repo settings.
 	 */
 	prepare_repo_settings(istate->repo);
-	if (!istate->repo->settings.command_requires_full_index &&
+	if (!repo_settings_get_command_requires_full_index(istate->repo) &&
 	    is_sparse_index_allowed(istate, 0))
 		istate->sparse_index = 1;
 }
@@ -2321,7 +2321,7 @@ int do_read_index(struct index_state *istate, const char *path, int must_exist)
 	 * settings and other properties of the index (if necessary).
 	 */
 	prepare_repo_settings(istate->repo);
-	if (istate->repo->settings.command_requires_full_index)
+	if (repo_settings_get_command_requires_full_index(istate->repo))
 		ensure_full_index(istate);
 	else
 		ensure_correct_sparsity(istate);

repo-settings.c

@@ -1,5 +1,6 @@
 #include "git-compat-util.h"
 #include "config.h"
+#include "gettext.h"
 #include "repo-settings.h"
 #include "repository.h"
 #include "midx.h"
@@ -131,14 +132,6 @@ void prepare_repo_settings(struct repository *r)
 			die("unknown fetch negotiation algorithm '%s'", strval);
 	}
 
-	/*
-	 * This setting guards all index reads to require a full index
-	 * over a sparse index. After suitable guards are placed in the
-	 * codebase around uses of the index, this setting will be
-	 * removed.
-	 */
-	r->settings.command_requires_full_index = 1;
-
 	if (!repo_config_get_ulong(r, "core.deltabasecachelimit", &ulongval))
 		r->settings.delta_base_cache_limit = ulongval;
 
@@ -156,6 +149,20 @@ void prepare_repo_settings(struct repository *r)
 		r->settings.packed_git_limit = ulongval;
 }
 
+int repo_settings_get_command_requires_full_index(struct repository *r)
+{
+	if (r->settings.command_requires_full_index >= 0)
+		return r->settings.command_requires_full_index;
+
+	if (git_env_bool("GIT_ALLOW_SPARSE_INDEX_WITHOUT_DECLARATION", 0)) {
+		r->settings.command_requires_full_index = 1;
+		return 1;
+	}
+
+	die(_("command has not declared sparse-index compatibility;\n"
+	      "set GIT_ALLOW_SPARSE_INDEX_WITHOUT_DECLARATION=1 to bypass"));
+}
+
 void repo_settings_clear(struct repository *r)
 {
 	struct repo_settings empty = REPO_SETTINGS_INIT;

repo-settings.h

@@ -72,6 +72,7 @@ struct repo_settings {
 	char *hooks_path;
 };
 #define REPO_SETTINGS_INIT { \
+	.command_requires_full_index = -1, \
 	.shared_repository = -1, \
 	.index_version = -1, \
 	.core_untracked_cache = UNTRACKED_CACHE_KEEP, \
@@ -85,6 +86,7 @@ struct repo_settings {
 
 void prepare_repo_settings(struct repository *r);
 void repo_settings_clear(struct repository *r);
+int repo_settings_get_command_requires_full_index(struct repository *r);
 
 /* Read the value for "core.logAllRefUpdates". */
 enum log_refs_config repo_settings_get_log_all_ref_updates(struct repository *repo);

repository.c

@@ -465,7 +465,7 @@ int repo_read_index(struct repository *repo)
 	res = read_index_from(repo->index, repo->index_file, repo->gitdir);
 
 	prepare_repo_settings(repo);
-	if (repo->settings.command_requires_full_index)
+	if (repo_settings_get_command_requires_full_index(repo))
 		ensure_full_index(repo->index);
 
 	/*

t/t1092-sparse-checkout-compatibility.sh

@@ -1558,6 +1558,24 @@ test_expect_success 'sparse-index is not expanded' '
 	)
 '
 
+test_expect_success 'sparse-index is not expanded: git mv' '
+	init_repos &&
+
+	ensure_not_expanded mv deep/a deep/renamed-a &&
+	ensure_not_expanded mv deep/deeper2 deep/moved-deeper2 &&
+
+	ensure_not_expanded reset --hard &&
+
+	# mv of a sparse directory without --sparse should fail with
+	# a useful hint, without expanding the index.
+	run_sparse_index_trace2 ! mv folder1 deep &&
+	test_region ! index ensure_full_index trace2.txt &&
+	grep "Use the --sparse option" sparse-index-error &&
+
+	ensure_not_expanded reset --hard &&
+	ensure_expanded mv --sparse folder1 deep
+'
+
 test_expect_success 'sparse-index is not expanded: merge conflict in cone' '
 	init_repos &&
 

t/t7002-mv-sparse-checkout.sh

@@ -238,7 +238,7 @@ test_expect_success 'refuse to move out-of-cone directory without --sparse' '
 
 	test_must_fail git mv folder1 sub 2>stderr &&
 	cat sparse_error_header >expect &&
-	echo folder1/file1 >>expect &&
+	echo folder1 >>expect &&
 	cat sparse_hint >>expect &&
 	test_cmp expect stderr
 '

unpack-trees.c

@@ -1906,7 +1906,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	trace2_region_enter("unpack_trees", "unpack_trees", the_repository);
 
 	prepare_repo_settings(repo);
-	if (repo->settings.command_requires_full_index) {
+	if (repo_settings_get_command_requires_full_index(repo)) {
 		ensure_full_index(o->src_index);
 		if (o->dst_index)
 			ensure_full_index(o->dst_index);
@@ -1964,7 +1964,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
 	o->internal.result.fsmonitor_has_run_once = o->src_index->fsmonitor_has_run_once;
 
 	if (!o->src_index->initialized &&
-	    !repo->settings.command_requires_full_index &&
+	    !repo_settings_get_command_requires_full_index(repo) &&
 	    is_sparse_index_allowed(&o->internal.result, 0))
 		o->internal.result.sparse_index = 1;