sparse-index: silently return when not using cone-mode patterns

While the sparse-index is only enabled when core.sparseCheckoutCone is
also enabled, it is possible for the user to modify the sparse-checkout
file manually in a way that does not match cone-mode patterns. In this
case, we should refuse to convert an index into a sparse index, since
the sparse_checkout_patterns will not be initialized with recursive and
parent path hashsets.

Also silently return if there are no cache entries, which is a simple
case: there are no paths to make sparse!

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

diff --git a/sparse-index.c b/sparse-index.c
index c6b4feec413a8ffeda31cadee1a85020abca466b..cd6e0d5f40814ca2a424e00f75cdabddce5f1c9f 100644 (file)
--- a/sparse-index.c
+++ b/sparse-index.c
@@ -130,7 +130,7 @@ static int index_has_unmerged_entries(struct index_state *istate)
 int convert_to_sparse(struct index_state *istate)
 {
        int test_env;
-       if (istate->split_index || istate->sparse_index ||
+       if (istate->split_index || istate->sparse_index || !istate->cache_nr ||
            !core_apply_sparse_checkout || !core_sparse_checkout_cone)
                return 0;
 
@@ -158,10 +158,16 @@ int convert_to_sparse(struct index_state *istate)
                        return 0;
        }
 
-       if (!istate->sparse_checkout_patterns->use_cone_patterns) {
-               warning(_("attempting to use sparse-index without cone mode"));
-               return -1;
-       }
+       /*
+        * We need cone-mode patterns to use sparse-index. If a user edits
+        * their sparse-checkout file manually, then we can detect during
+        * parsing that they are not actually using cone-mode patterns and
+        * hence we need to abort this conversion _without error_. Warnings
+        * already exist in the pattern parsing to inform the user of their
+        * bad patterns.
+        */
+       if (!istate->sparse_checkout_patterns->use_cone_patterns)
+               return 0;
 
        /*
         * NEEDSWORK: If we have unmerged entries, then stay full.