[RFC PATCH 7/7] rm: honor sparse checkout patterns

[Matheus Tavares <matheus.bernardino@usp.br>]

`git add` refrains from adding or updating paths outside the sparsity
rules, but `git rm` doesn't follow the same restrictions. This is
somewhat counter-intuitive and inconsistent. So make `rm` honor the
sparse checkout and advise on how to remove SKIP_WORKTREE entries, just
like `add` does. Also add a few tests for the new behavior.

Suggested-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Matheus Tavares <matheus.bernardino@usp.br>
---
 Documentation/config/advice.txt  |  5 +--
 Documentation/git-rm.txt         |  4 ++-
 builtin/rm.c                     | 35 ++++++++++++++-------
 t/t3600-rm.sh                    | 54 ++++++++++++++++++++++++++++++++
 t/t7011-skip-worktree-reading.sh |  5 ---
 5 files changed, 84 insertions(+), 19 deletions(-)

diff --git a/Documentation/config/advice.txt b/Documentation/config/advice.txt
index d53eafa00b..bdd423ade4 100644
--- a/Documentation/config/advice.txt
+++ b/Documentation/config/advice.txt
@@ -120,6 +120,7 @@ advice.*::
 		Advice shown if a user runs the add command without providing
 		the pathspec parameter.
 	updateSparsePath::
-		Advice shown if the pathspec given to linkgit:git-add[1] only
-		matches index entries outside the current sparse-checkout.
+		Advice shown if the pathspec given to linkgit:git-add[1] or
+		linkgit:git-rm[1] only matches index entries outside the
+		current sparse-checkout.
 --
diff --git a/Documentation/git-rm.txt b/Documentation/git-rm.txt
index ab750367fd..26e9b28470 100644
--- a/Documentation/git-rm.txt
+++ b/Documentation/git-rm.txt
@@ -23,7 +23,9 @@ branch, and no updates to their contents can be staged in the index,
 though that default behavior can be overridden with the `-f` option.
 When `--cached` is given, the staged content has to
 match either the tip of the branch or the file on disk,
-allowing the file to be removed from just the index.
+allowing the file to be removed from just the index. When
+sparse-checkouts are in use (see linkgit:git-sparse-checkout[1]),
+`git rm` will only remove paths within the sparse-checkout patterns.
 
 
 OPTIONS
diff --git a/builtin/rm.c b/builtin/rm.c
index 4858631e0f..d23a3b2164 100644
--- a/builtin/rm.c
+++ b/builtin/rm.c
@@ -5,6 +5,7 @@
  */
 #define USE_THE_INDEX_COMPATIBILITY_MACROS
 #include "builtin.h"
+#include "advice.h"
 #include "config.h"
 #include "lockfile.h"
 #include "dir.h"
@@ -254,7 +255,7 @@ static struct option builtin_rm_options[] = {
 int cmd_rm(int argc, const char **argv, const char *prefix)
 {
 	struct lock_file lock_file = LOCK_INIT;
-	int i;
+	int i, ret = 0;
 	struct pathspec pathspec;
 	char *seen;
 
@@ -295,6 +296,8 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	for (i = 0; i < active_nr; i++) {
 		const struct cache_entry *ce = active_cache[i];
+		if (ce_skip_worktree(ce))
+			continue;
 		if (!ce_path_match(&the_index, ce, &pathspec, seen))
 			continue;
 		ALLOC_GROW(list.entry, list.nr + 1, list.alloc);
@@ -308,24 +311,34 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 	if (pathspec.nr) {
 		const char *original;
 		int seen_any = 0;
+		char *skip_worktree_seen = NULL;
+		struct string_list only_match_skip_worktree = STRING_LIST_INIT_NODUP;
+
 		for (i = 0; i < pathspec.nr; i++) {
 			original = pathspec.items[i].original;
-			if (!seen[i]) {
-				if (!ignore_unmatch) {
-					die(_("pathspec '%s' did not match any files"),
-					    original);
-				}
-			}
-			else {
+			if (seen[i])
 				seen_any = 1;
-			}
+			else if (ignore_unmatch)
+				continue;
+			else if (matches_skip_worktree(&pathspec, i, &skip_worktree_seen))
+				string_list_append(&only_match_skip_worktree, original);
+			else
+				die(_("pathspec '%s' did not match any files"), original);
+
 			if (!recursive && seen[i] == MATCHED_RECURSIVELY)
 				die(_("not removing '%s' recursively without -r"),
 				    *original ? original : ".");
 		}
 
+		if (only_match_skip_worktree.nr) {
+			advise_on_updating_sparse_paths(&only_match_skip_worktree);
+			ret = 1;
+		}
+		free(skip_worktree_seen);
+		string_list_clear(&only_match_skip_worktree, 0);
+
 		if (!seen_any)
-			exit(0);
+			exit(ret);
 	}
 
 	if (!index_only)
@@ -405,5 +418,5 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 			       COMMIT_LOCK | SKIP_IF_UNCHANGED))
 		die(_("Unable to write new index file"));
 
-	return 0;
+	return ret;
 }
diff --git a/t/t3600-rm.sh b/t/t3600-rm.sh
index 7547f11a5c..0e5cf945d9 100755
--- a/t/t3600-rm.sh
+++ b/t/t3600-rm.sh
@@ -907,4 +907,58 @@ test_expect_success 'rm empty string should fail' '
 	test_must_fail git rm -rf ""
 '
 
+test_expect_success 'setup repo for tests with sparse-checkout' '
+	git init sparse &&
+	(
+		cd sparse &&
+		mkdir -p sub/dir &&
+		touch a b c sub/d sub/dir/e &&
+		git add -A &&
+		git commit -m files
+	) &&
+
+	cat >sparse_entry_b_error <<-EOF &&
+	The following pathspecs only matched index entries outside the current
+	sparse checkout:
+	b
+	EOF
+
+	cat >b_error_and_hint sparse_entry_b_error - <<-EOF
+	hint: Disable or modify the sparsity rules if you intend to update such entries.
+	hint: Disable this message with "git config advice.updateSparsePath false"
+	EOF
+'
+
+test_expect_success 'rm should respect sparse-checkout' '
+	git -C sparse sparse-checkout set "/a" &&
+	test_must_fail git -C sparse rm b 2>stderr &&
+	test_i18ncmp b_error_and_hint stderr
+'
+
+test_expect_success 'rm obeys advice.updateSparsePath' '
+	git -C sparse reset --hard &&
+	git -C sparse sparse-checkout set "/a" &&
+	test_must_fail git -C sparse -c advice.updateSparsePath=false rm b 2>stderr &&
+	test_i18ncmp sparse_entry_b_error stderr
+
+'
+
+test_expect_success 'recursive rm should respect sparse-checkout' '
+	(
+		cd sparse &&
+		git reset --hard &&
+		git sparse-checkout set "sub/dir" &&
+		git rm -r sub &&
+		git status --porcelain -uno >../actual
+	) &&
+	echo "D  sub/dir/e" >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'do not advice about sparse entries when they do not match the pathspec' '
+	test_must_fail git -C sparse rm nonexistent 2>stderr &&
+	test_i18ngrep "fatal: pathspec .nonexistent. did not match any files" stderr &&
+	test_i18ngrep ! "The following pathspecs only matched index entries" stderr
+'
+
 test_done
diff --git a/t/t7011-skip-worktree-reading.sh b/t/t7011-skip-worktree-reading.sh
index 37525cae3a..f87749951f 100755
--- a/t/t7011-skip-worktree-reading.sh
+++ b/t/t7011-skip-worktree-reading.sh
@@ -141,11 +141,6 @@ test_expect_success 'diff-files does not examine skip-worktree dirty entries' '
 	test -z "$(git diff-files -- one)"
 '
 
-test_expect_success 'git-rm succeeds on skip-worktree absent entries' '
-	setup_absent &&
-	git rm 1
-'
-
 test_expect_success 'commit on skip-worktree absent entries' '
 	git reset &&
 	setup_absent &&
-- 
2.29.2