Subject: Re: [Outreachy PATCH v3 2/3] environment: environment: stop using core.sparseCheckout globally

From: Toon Claes <[email-masked]>
Date: Thu, 22 Jan 2026 13:13:45 +0100

Olamide Caleb Bello <[email-masked]> writes:

It seems you have 'environment:' twice in the title?

> The config value `core.sparseCheckout` is parsed in
> `git_default_core_config()` and stored globally in
> `core_appy_sparse_checkout`. This could cause unintended behaviours

s/core_appy_sparse_checkout/core_apply_sparse_checkout/ ?

> when different Git repositories running in the same process access this
> variable.
>
> Move the parsed value into `struct repo_config_values` to retains current
> behaviours while achieving the repository scoped access.
>
> Suggested-by: Phillip Wood <[email-masked]>
> Mentored-by: Christian Couder <[email-masked]>
> Mentored-by: Usman Akinyemi <[email-masked]>
> Signed-off-by: Olamide Caleb Bello <[email-masked]>
> ---
>  builtin/backfill.c        |  2 +-
>  builtin/clone.c           |  2 +-
>  builtin/grep.c            |  2 +-
>  builtin/mv.c              |  2 +-
>  builtin/sparse-checkout.c | 22 +++++++++++-----------
>  builtin/worktree.c        |  2 +-
>  dir.c                     |  2 +-
>  environment.c             |  4 ++--
>  environment.h             |  2 +-
>  sparse-index.c            |  6 ++++--
>  unpack-trees.c            |  2 +-
>  wt-status.c               |  2 +-
>  12 files changed, 26 insertions(+), 24 deletions(-)
>
> diff --git a/builtin/backfill.c b/builtin/backfill.c
> index e80fc1b694..5fc8c51ed1 100644
> --- a/builtin/backfill.c
> +++ b/builtin/backfill.c
> @@ -139,7 +139,7 @@ int cmd_backfill(int argc, const char **argv, const char *prefix, struct reposit
>  	repo_config(repo, git_default_config, NULL);
>  
>  	if (ctx.sparse < 0)
> -		ctx.sparse = core_apply_sparse_checkout;
> +		ctx.sparse = repo->config_values.sparse_checkout;
>  
>  	result = do_backfill(&ctx);
>  	backfill_context_clear(&ctx);
> diff --git a/builtin/clone.c b/builtin/clone.c
> index b19b302b06..b6b19e83d1 100644
> --- a/builtin/clone.c
> +++ b/builtin/clone.c
> @@ -623,7 +623,7 @@ static int git_sparse_checkout_init(const char *repo)
>  	 * We must apply the setting in the current process
>  	 * for the later checkout to use the sparse-checkout file.
>  	 */
> -	core_apply_sparse_checkout = 1;
> +	the_repository->config_values.sparse_checkout = 1;
>  
>  	cmd.git_cmd = 1;
>  	if (run_command(&cmd)) {
> diff --git a/builtin/grep.c b/builtin/grep.c
> index 53cccf2d25..525edb5e9c 100644
> --- a/builtin/grep.c
> +++ b/builtin/grep.c
> @@ -482,7 +482,7 @@ static int grep_submodule(struct grep_opt *opt,
>  	 *	"forget" the sparse-index feature switch. As a result, the index
>  	 *	of these submodules are expanded unexpectedly.
>  	 *
> -	 * 2. "core_apply_sparse_checkout"
> +	 * 2. "sparse_checkout"
>  	 *	When running `grep` in the superproject, this setting is
>  	 *	populated using the superproject's configs. However, once
>  	 *	initialized, this config is globally accessible and is read by
> diff --git a/builtin/mv.c b/builtin/mv.c
> index d43925097b..511620747b 100644
> --- a/builtin/mv.c
> +++ b/builtin/mv.c
> @@ -572,7 +572,7 @@ int cmd_mv(int argc,
>  		rename_index_entry_at(the_repository->index, pos, dst);
>  
>  		if (ignore_sparse &&
> -		    core_apply_sparse_checkout &&
> +		    the_repository->config_values.sparse_checkout &&
>  		    core_sparse_checkout_cone) {
>  			/*
>  			 * NEEDSWORK: we are *not* paying attention to
> diff --git a/builtin/sparse-checkout.c b/builtin/sparse-checkout.c
> index 15d51e60a8..1c2c39b968 100644
> --- a/builtin/sparse-checkout.c
> +++ b/builtin/sparse-checkout.c
> @@ -63,7 +63,7 @@ static int sparse_checkout_list(int argc, const char **argv, const char *prefix,
>  	int res;
>  
>  	setup_work_tree();
> -	if (!core_apply_sparse_checkout)
> +	if (!the_repository->config_values.sparse_checkout)
>  		die(_("this worktree is not sparse"));
>  
>  	argc = parse_options(argc, argv, prefix,
> @@ -400,11 +400,11 @@ static int set_config(struct repository *repo,
>  
>  static enum sparse_checkout_mode update_cone_mode(int *cone_mode) {
>  	/* If not specified, use previous definition of cone mode */
> -	if (*cone_mode == -1 && core_apply_sparse_checkout)
> +	if (*cone_mode == -1 && the_repository->config_values.sparse_checkout)
>  		*cone_mode = core_sparse_checkout_cone;
>  
>  	/* Set cone/non-cone mode appropriately */
> -	core_apply_sparse_checkout = 1;
> +	the_repository->config_values.sparse_checkout = 1;
>  	if (*cone_mode == 1 || *cone_mode == -1) {
>  		core_sparse_checkout_cone = 1;
>  		return MODE_CONE_PATTERNS;
> @@ -418,7 +418,7 @@ static int update_modes(struct repository *repo, int *cone_mode, int *sparse_ind
>  	int mode, record_mode;
>  
>  	/* Determine if we need to record the mode; ensure sparse checkout on */
> -	record_mode = (*cone_mode != -1) || !core_apply_sparse_checkout;
> +	record_mode = (*cone_mode != -1) || !repo->config_values.sparse_checkout;
>  
>  	mode = update_cone_mode(cone_mode);
>  	if (record_mode && set_config(repo, mode))
> @@ -699,9 +699,9 @@ static int modify_pattern_list(struct repository *repo,
>  		break;
>  	}
>  
> -	if (!core_apply_sparse_checkout) {
> +	if (!repo->config_values.sparse_checkout) {
>  		set_config(repo, MODE_ALL_PATTERNS);
> -		core_apply_sparse_checkout = 1;
> +		repo->config_values.sparse_checkout = 1;
>  		changed_config = 1;
>  	}
>  
> @@ -798,7 +798,7 @@ static int sparse_checkout_add(int argc, const char **argv, const char *prefix,
>  	int ret;
>  
>  	setup_work_tree();
> -	if (!core_apply_sparse_checkout)
> +	if (!repo->config_values.sparse_checkout)
>  		die(_("no sparse-checkout to add to"));
>  
>  	repo_read_index(repo);
> @@ -907,7 +907,7 @@ static int sparse_checkout_reapply(int argc, const char **argv,
>  	};
>  
>  	setup_work_tree();
> -	if (!core_apply_sparse_checkout)
> +	if (!repo->config_values.sparse_checkout)
>  		die(_("must be in a sparse-checkout to reapply sparsity patterns"));
>  
>  	reapply_opts.cone_mode = -1;
> @@ -969,7 +969,7 @@ static int sparse_checkout_clean(int argc, const char **argv,
>  	};
>  
>  	setup_work_tree();
> -	if (!core_apply_sparse_checkout)
> +	if (!repo->config_values.sparse_checkout)
>  		die(_("must be in a sparse-checkout to clean directories"));
>  	if (!core_sparse_checkout_cone)
>  		die(_("must be in a cone-mode sparse-checkout to clean directories"));
> @@ -1035,7 +1035,7 @@ static int sparse_checkout_disable(int argc, const char **argv,
>  	struct pattern_list pl;
>  
>  	/*
> -	 * We do not exit early if !core_apply_sparse_checkout; due to the
> +	 * We do not exit early if !repo->config_values.sparse_checkout; due to the
>  	 * ability for users to manually muck things up between
>  	 *   direct editing of .git/info/sparse-checkout
>  	 *   running read-tree -m u HEAD or update-index --skip-worktree
> @@ -1061,7 +1061,7 @@ static int sparse_checkout_disable(int argc, const char **argv,
>  	hashmap_init(&pl.recursive_hashmap, pl_hashmap_cmp, NULL, 0);
>  	hashmap_init(&pl.parent_hashmap, pl_hashmap_cmp, NULL, 0);
>  	pl.use_cone_patterns = 0;
> -	core_apply_sparse_checkout = 1;
> +	repo->config_values.sparse_checkout = 1;
>  
>  	add_pattern("/*", empty_base, 0, &pl, 0);
>  
> diff --git a/builtin/worktree.c b/builtin/worktree.c
> index fbdaf2eb2e..e401b8253e 100644
> --- a/builtin/worktree.c
> +++ b/builtin/worktree.c
> @@ -536,7 +536,7 @@ static int add_worktree(const char *path, const char *refname,
>  	 * If the current worktree has sparse-checkout enabled, then copy
>  	 * the sparse-checkout patterns from the current worktree.
>  	 */
> -	if (core_apply_sparse_checkout)
> +	if (wt->repo->config_values.sparse_checkout)
>  		copy_sparse_checkout(sb_repo.buf);
>  
>  	/*
> diff --git a/dir.c b/dir.c
> index b00821f294..56b412a6d2 100644
> --- a/dir.c
> +++ b/dir.c
> @@ -1551,7 +1551,7 @@ enum pattern_match_result path_matches_pattern_list(
>  
>  int init_sparse_checkout_patterns(struct index_state *istate)
>  {
> -	if (!core_apply_sparse_checkout)
> +	if (!istate->repo->config_values.sparse_checkout)
>  		return 1;
>  	if (istate->sparse_checkout_patterns)
>  		return 0;
> diff --git a/environment.c b/environment.c
> index 283db0a1a0..6633542750 100644
> --- a/environment.c
> +++ b/environment.c
> @@ -74,7 +74,6 @@ enum push_default_type push_default = PUSH_DEFAULT_UNSPECIFIED;
>  #endif
>  enum object_creation_mode object_creation_mode = OBJECT_CREATION_MODE;
>  int grafts_keep_true_parents;
> -int core_apply_sparse_checkout;
>  int core_sparse_checkout_cone;
>  int sparse_expect_files_outside_of_patterns;
>  int precomposed_unicode = -1; /* see probe_utf8_pathname_composition() */
> @@ -546,7 +545,7 @@ static int git_default_core_config(const char *var, const char *value,
>  	}
>  
>  	if (!strcmp(var, "core.sparsecheckout")) {
> -		core_apply_sparse_checkout = git_config_bool(var, value);
> +		cfg->sparse_checkout = git_config_bool(var, value);
>  		return 0;
>  	}
>  
> @@ -761,4 +760,5 @@ int git_default_config(const char *var, const char *value,
>  void repo_config_values_init(struct repo_config_values *cfg)
>  {
>  	cfg->attributes_file_path = NULL;
> +	cfg->sparse_checkout = 0;
>  }
> diff --git a/environment.h b/environment.h
> index aea73ff25b..3b5ff7094a 100644
> --- a/environment.h
> +++ b/environment.h
> @@ -88,6 +88,7 @@ struct strvec;
>  struct repo_config_values {
>  	/* core config values */
>  	char *attributes_file_path;
> +	int sparse_checkout;
>  };
>  
>  /*
> @@ -169,7 +170,6 @@ extern int precomposed_unicode;
>  extern int protect_hfs;
>  extern int protect_ntfs;
>  
> -extern int core_apply_sparse_checkout;

In the field you're adding to 'struct repo_config_values' you have
dropped the 'core_' prefix, what the reason for that? If I understand it
correctly also settings from other sections might end up in that struct,
so wouldn't it be better to keep the prefix?

>  extern int core_sparse_checkout_cone;
>  extern int sparse_expect_files_outside_of_patterns;
>  
> diff --git a/sparse-index.c b/sparse-index.c
> index 76f90da5f5..6dd8dd679d 100644
> --- a/sparse-index.c
> +++ b/sparse-index.c
> @@ -152,7 +152,8 @@ static int index_has_unmerged_entries(struct index_state *istate)
>  
>  int is_sparse_index_allowed(struct index_state *istate, int flags)
>  {
> -	if (!core_apply_sparse_checkout || !core_sparse_checkout_cone)
> +	struct repo_config_values *cfg = &istate->repo->config_values;
> +	if (!cfg->sparse_checkout || !core_sparse_checkout_cone)
>  		return 0;
>  
>  	if (!(flags & SPARSE_INDEX_MEMORY_ONLY)) {
> @@ -670,7 +671,8 @@ static void clear_skip_worktree_from_present_files_full(struct index_state *ista
>  
>  void clear_skip_worktree_from_present_files(struct index_state *istate)
>  {
> -	if (!core_apply_sparse_checkout ||
> +	struct repo_config_values *cfg = &istate->repo->config_values;
> +	if (!cfg->sparse_checkout ||
>  	    sparse_expect_files_outside_of_patterns)
>  		return;
>  
> diff --git a/unpack-trees.c b/unpack-trees.c
> index f38c761ab9..2bdfa1334c 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -1924,7 +1924,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
>  	if (o->prefix)
>  		update_sparsity_for_prefix(o->prefix, o->src_index);
>  
> -	if (!core_apply_sparse_checkout || !o->update)
> +	if (!repo->config_values.sparse_checkout || !o->update)
>  		o->skip_sparse_checkout = 1;
>  	if (!o->skip_sparse_checkout) {
>  		memset(&pl, 0, sizeof(pl));
> diff --git a/wt-status.c b/wt-status.c
> index e12adb26b9..a2e388606f 100644
> --- a/wt-status.c
> +++ b/wt-status.c
> @@ -1764,7 +1764,7 @@ static void wt_status_check_sparse_checkout(struct repository *r,
>  	int skip_worktree = 0;
>  	int i;
>  
> -	if (!core_apply_sparse_checkout || r->index->cache_nr == 0) {
> +	if (!r->config_values.sparse_checkout || r->index->cache_nr == 0) {
>  		/*
>  		 * Don't compute percentage of checked out files if we
>  		 * aren't in a sparse checkout or would get division by 0.
> -- 
> 2.34.1
>
>

-- 
Cheers,
Toon