unpack-trees: provide warnings on sparse updates for unmerged paths too

When sparse-checkout runs to update the list of sparsity patterns, it
gives warnings if it can't remove paths from the working tree because
those files have dirty changes.  Add a similar warning for unmerged
paths as well.

Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1091-sparse-checkout-builtin.sh

@@ -345,6 +345,31 @@ test_expect_success 'sparse-checkout (init|set|disable) warns with dirty status'
 	test_path_is_file dirty/folder1/a
 '
 
+test_expect_success 'sparse-checkout (init|set|disable) warns with unmerged status' '
+	git clone repo unmerged &&
+
+	cat >input <<-EOF &&
+	0 0000000000000000000000000000000000000000	folder1/a
+	100644 $(git -C unmerged rev-parse HEAD:folder1/a) 1	folder1/a
+	EOF
+	git -C unmerged update-index --index-info <input &&
+
+	git -C unmerged sparse-checkout init 2>err &&
+	test_i18ngrep "warning.*The following paths are unmerged" err &&
+
+	git -C unmerged sparse-checkout set /folder2/* /deep/deeper1/* 2>err &&
+	test_i18ngrep "warning.*The following paths are unmerged" err &&
+	test_path_is_file dirty/folder1/a &&
+
+	git -C unmerged sparse-checkout disable 2>err &&
+	test_i18ngrep "warning.*The following paths are unmerged" err &&
+
+	git -C unmerged reset --hard &&
+	git -C unmerged sparse-checkout init &&
+	git -C unmerged sparse-checkout set /folder2/* /deep/deeper1/* &&
+	git -C unmerged sparse-checkout disable
+'
+
 test_expect_success 'cone mode: set with core.ignoreCase=true' '
 	rm repo/.git/info/sparse-checkout &&
 	git -C repo sparse-checkout init --cone &&

unpack-trees.c

@@ -52,6 +52,9 @@ static const char *unpack_plumbing_errors[NB_UNPACK_TREES_WARNING_TYPES] = {
 	/* WARNING_SPARSE_NOT_UPTODATE_FILE */
 	"Path '%s' not uptodate; will not remove from working tree.",
 
+	/* WARNING_SPARSE_UNMERGED_FILE */
+	"Path '%s' unmerged; will not remove from working tree.",
+
 	/* WARNING_SPARSE_ORPHANED_NOT_OVERWRITTEN */
 	"Path '%s' already present; will not overwrite with sparse update.",
 };
@@ -173,6 +176,8 @@ void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 
 	msgs[WARNING_SPARSE_NOT_UPTODATE_FILE] =
 		_("The following paths are not up to date and were left despite sparse patterns:\n%s");
+	msgs[WARNING_SPARSE_UNMERGED_FILE] =
+		_("The following paths are unmerged and were left despite sparse patterns:\n%s");
 	msgs[WARNING_SPARSE_ORPHANED_NOT_OVERWRITTEN] =
 		_("The following paths were already present and thus not updated despite sparse patterns:\n%s");
 
@@ -548,6 +553,23 @@ static int apply_sparse_checkout(struct index_state *istate,
 	return 0;
 }
 
+static int warn_conflicted_path(struct index_state *istate,
+				int i,
+				struct unpack_trees_options *o)
+{
+	char *conflicting_path = istate->cache[i]->name;
+	int count = 0;
+
+	add_rejected_path(o, WARNING_SPARSE_UNMERGED_FILE, conflicting_path);
+
+	/* Find out how many higher stage entries at same path */
+	while (++count < istate->cache_nr &&
+	       !strcmp(conflicting_path,
+		       istate->cache[i+count]->name))
+		/* do nothing */;
+	return count;
+}
+
 static inline int call_unpack_fn(const struct cache_entry * const *src,
 				 struct unpack_trees_options *o)
 {
@@ -1793,6 +1815,14 @@ enum update_sparsity_result update_sparsity(struct unpack_trees_options *o)
 	for (i = 0; i < o->src_index->cache_nr; i++) {
 		struct cache_entry *ce = o->src_index->cache[i];
 
+
+		if (ce_stage(ce)) {
+			/* -1 because for loop will increment by 1 */
+			i += warn_conflicted_path(o->src_index, i, o) - 1;
+			ret = UPDATE_SPARSITY_WARNINGS;
+			continue;
+		}
+
 		if (apply_sparse_checkout(o->src_index, ce, o))
 			ret = UPDATE_SPARSITY_WARNINGS;
 

unpack-trees.h

@@ -27,6 +27,7 @@ enum unpack_trees_error_types {
 	NB_UNPACK_TREES_ERROR_TYPES,
 
 	WARNING_SPARSE_NOT_UPTODATE_FILE,
+	WARNING_SPARSE_UNMERGED_FILE,
 	WARNING_SPARSE_ORPHANED_NOT_OVERWRITTEN,
 
 	NB_UNPACK_TREES_WARNING_TYPES,