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

>
> Hi Olamide
>
> On 17/01/2026 20:59, Olamide Caleb Bello wrote:
> > 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
> > 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.
>
> It doesn't achieve repository scoped access though because we only ever
> populate the values in "the_repository", all other instances of "struct
> repository" are initialized by config_values_init() but not the config
> settings.

>
> > 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;
>
> Using "repo" rather than "the_repository" here is dangerous because only
> "the_repository" contains the parsed config. This applies throughout
> this patch.

>
> >
> >       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"
>
> That should be something like config_values.sparse_checkout to make it
> clear that "sparse_checkout" is the name of a member of a struct, not
> the name of a variable.

>
> > 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;
>
> There are several other sparse checkout variables like
> core_sparse_checkout_cone that we'll need to convert in the future so
> "apply_sparse_checkout" or "sparse_checkout_apply" would be better names.

>
> Thanks
>
> Phillip
>
>
> >   };
> >
> >   /*
> > @@ -169,7 +170,6 @@ extern int precomposed_unicode;
> >   extern int protect_hfs;
> >   extern int protect_ntfs;
> >
> > -extern int core_apply_sparse_checkout;
> >   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.
>