sparse checkout: fix a few bugs and check argument validity for set/add

== Maintainer notes ==

Note: There is a small textual and small semantic conflict with ds/sparse-checkout-requires-per-worktree-config in seen. I included the diff with the correct resolution near the end of this cover letter. If you'd prefer I rebased on top of ds/sparse-chckout-requires-per-worktree-config, let me know.

== Overview ==

This series continues attempts to make sparse-checkouts more user friendly. A quick overview:

* Patches 1-2 fix existing bugs from en/sparse-checkout-set (i.e. in v2.35.0)
* Patch 3 fixes sparse-checkout-from-subdirectories-ignores-"prefix" (see
https://lore.kernel.org/git/[email protected]/),
in cone mode. Since we'll get nasty surprises whether we use or don't use "prefix" for non-cone mode, simply throw an error if set/add subcommands of sparse-checkout are run from a subdirectory.
* Patches 4-5 check positional arguments to set/add and provide errors/warnings for very likely mistakes. It also adds a --skip-checks flag for overridding in case you have a very unusual situation.

== Update history ==

Changes since v4:

* have --skip-checks enable running from a subdirectory in non-cone mode
* make sure new die() messages are marked for translation (and using single quotes instead of double)

Changes since v3:

* Use strpbrk() instead of multiple strchr(), fix commit message relative to backslashes.

Changes since v2:

* Dropped patch 5
* Added Stolee's Reviewed-by

Changes since v1:

* Dropped the commit changing cone-mode to default (patch 7, which will be split into multiple patches and submitted as a separate series)
* Removed the RFC label
* Decided to error out when running set/add with paths from a subdirectory in non-cone mode, and added tests
* Changed the warning for non-cone mode with individual files to point out that the user is likely trying to select an individual file, but should likely add a leading slash to ensure that is what happens
* Fixed typos, removed unnecessary condition checks

== Conflict resolution ==

Patch to resolve textual and semantic conflict with ds/sparse-checkout-requires-per-worktree-config:

remerge CONFLICT (content): Merge conflict in t/t1091-sparse-checkout-builtin.sh index 3c6adeb885..3a95d2996d 100755

@@ -275,24 +275,8 @@ test_expect_success 'sparse-index enabled and disabled' '
     diff -u sparse full | tail -n +3 >actual &&
     test_cmp expect actual &&
 
-<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< 286c22e5ec (sparse-checkout: reject arguments in cone-mode that look like patterns)
     git -C repo config --list >config &&
-    ! grep index.sparse config
-|||||||||||||||||||||||||||||||| 89bece5c8c
-        diff -u sparse full | tail -n +3 >actual &&
-        test_cmp expect actual &&
-
-        git -C repo config --list >config &&
-        ! grep index.sparse config
-    )
-================================
-        diff -u sparse full | tail -n +3 >actual &&
-        test_cmp expect actual &&
-
-        git -C repo config --list >config &&
-        test_cmp_config -C repo false index.sparse
-    )
->>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 3ce1138272 (config: make git_configset_get_string_tmp() private)
+    test_cmp_config -C repo false index.sparse
 '
 
 test_expect_success 'cone mode: init and set' '

@@ -532,6 +516,7 @@ test_expect_success 'reapply can handle config options' '
     cat >expect <<-\EOF &&
     core.sparsecheckout=true
     core.sparsecheckoutcone=true
+    index.sparse=false
     EOF
     test_cmp expect actual &&
 

@@ -539,6 +524,8 @@ test_expect_success 'reapply can handle config options' '
     git -C repo config --worktree --list >actual &&
     cat >expect <<-\EOF &&
     core.sparsecheckout=true
+    core.sparsecheckoutcone=false
+    index.sparse=false
     EOF
     test_cmp expect actual &&
 

== CCs ==

Elijah Newren (5):
sparse-checkout: correct reapply's handling of options
sparse-checkout: correctly set non-cone mode when expected
sparse-checkout: pay attention to prefix for {set, add}
sparse-checkout: error or warn when given individual files
sparse-checkout: reject arguments in cone-mode that look like patterns

 builtin/sparse-checkout.c          | 78 +++++++++++++++++++++++++--
 t/t1091-sparse-checkout-builtin.sh | 87 +++++++++++++++++++++++++++++-
 2 files changed, 158 insertions(+), 7 deletions(-)

base-commit: b80121027d1247a0754b3cc46897fee75c050b44
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1118%2Fnewren%2Fsparse-checkout-default-and-arg-validity-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1118/newren/sparse-checkout-default-and-arg-validity-v5
Pull-Request: https://github.com/gitgitgadget/git/pull/1118

Range-diff vs v4:

 1:  5215b7f7179 = 1:  5215b7f7179 sparse-checkout: correct reapply's handling of options
 2:  0c2ab523e74 = 2:  0c2ab523e74 sparse-checkout: correctly set non-cone mode when expected
 3:  e68b0a37ff3 ! 3:  06cf71bfca4 sparse-checkout: pay attention to prefix for {set, add}
     @@ builtin/sparse-checkout.c: static int modify_pattern_list(int argc, const char *
      +	if (!argc)
      +		return;
      +
     -+	if (prefix && *prefix) {
     ++	if (prefix && *prefix && core_sparse_checkout_cone) {
      +		/*
      +		 * The args are not pathspecs, so unfortunately we
      +		 * cannot imitate how cmd_add() uses parse_pathspec().
     @@ builtin/sparse-checkout.c: static int modify_pattern_list(int argc, const char *
      +		int i;
      +		int prefix_len = strlen(prefix);
      +
     -+		if (!core_sparse_checkout_cone)
     -+			die("please run from the toplevel directory in non-cone mode");
     -+
      +		for (i = 0; i < argc; i++)
      +			argv[i] = prefix_path(prefix, prefix_len, argv[i]);
      +	}
     ++
     ++	if (prefix && *prefix && !core_sparse_checkout_cone)
     ++		die(_("please run from the toplevel directory in non-cone mode"));
     ++
      +}
      +
       static char const * const builtin_sparse_checkout_add_usage[] = {
 4:  1fdebc1953f ! 4:  78bf6016687 sparse-checkout: error or warn when given individual files
     @@ Commit message
          in any directory.  Thus users will likely want to prefix any paths they
          specify with a leading '/' character; warn users if the patterns they
          specify exactly name a file because it means they are likely missing
     -    such a missing leading slash.
     +    such a leading slash.
      
          Reviewed-by: Derrick Stolee <[email protected]>
          Signed-off-by: Elijah Newren <[email protected]>
     @@ builtin/sparse-checkout.c: static void sanitize_paths(int argc, const char **arg
      -		int i;
       		int prefix_len = strlen(prefix);
       
     - 		if (!core_sparse_checkout_cone)
     -@@ builtin/sparse-checkout.c: static void sanitize_paths(int argc, const char **argv, const char *prefix)
       		for (i = 0; i < argc; i++)
       			argv[i] = prefix_path(prefix, prefix_len, argv[i]);
       	}
     -+
     + 
      +	if (skip_checks)
      +		return;
      +
     + 	if (prefix && *prefix && !core_sparse_checkout_cone)
     + 		die(_("please run from the toplevel directory in non-cone mode"));
     + 
      +	for (i = 0; i < argc; i++) {
      +		struct cache_entry *ce;
      +		struct index_state *index = the_repository->index;
     @@ builtin/sparse-checkout.c: static void sanitize_paths(int argc, const char **arg
      +			continue;
      +
      +		if (core_sparse_checkout_cone)
     -+			die(_("\"%s\" is not a directory; to treat it as a directory anyway, rerun with --skip-checks"), argv[i]);
     ++			die(_("'%s' is not a directory; to treat it as a directory anyway, rerun with --skip-checks"), argv[i]);
      +		else
     -+			warning(_("pass a leading slash before paths such as \"%s\" if you want a single file (see NON-CONE PROBLEMS in the git-sparse-checkout manual)."), argv[i]);
     ++			warning(_("pass a leading slash before paths such as '%s' if you want a single file (see NON-CONE PROBLEMS in the git-sparse-checkout manual)."), argv[i]);
      +	}
       }

5: d68682c25c4 ! 5: 53183d07502 sparse-checkout: reject arguments in cone-mode that look like patterns
@@ Commit message

## builtin/sparse-checkout.c ##
@@ builtin/sparse-checkout.c: static void sanitize_paths(int argc, const char **argv,
- if (skip_checks)
- return;
+ if (prefix && *prefix && !core_sparse_checkout_cone)
+ die(_("please run from the toplevel directory in non-cone mode"));

+ if (core_sparse_checkout_cone) {
+ for (i = 0; i < argc; i++) {

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