[RFC PATCH 11/21] cache-tree.c: use bug() and BUG_if_bug()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change "BUG" output originally added in a97e4075a16 (Keep
rename/rename conflicts of intermediate merges while doing recursive
merge, 2007-03-31), and later made to say it was a "BUG" in
19c6a4f8369 (merge-recursive: do not return NULL only to cause
segfault, 2010-01-21) to use the new bug() function.

This gets the same job done with less code, this changes the output a
bit, but since we're emitting BUG output let's say it's OK to prefix
every line with the "unmerged index entry" message, instead of
optimizing for readability. doing it this way gets rid of any state
management in the loop itself in favor of BUG_if_bug().

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
 cache-tree.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/cache-tree.c b/cache-tree.c
index 79d168192d7..944e9709ae0 100644
--- a/cache-tree.c
+++ b/cache-tree.c
@@ -692,14 +692,13 @@ struct tree* write_in_core_index_as_tree(struct repository *repo) {
 	ret = write_index_as_tree_internal(&o, index_state, was_valid, 0, NULL);
 	if (ret == WRITE_TREE_UNMERGED_INDEX) {
 		int i;
-		fprintf(stderr, "BUG: There are unmerged index entries:\n");
 		for (i = 0; i < index_state->cache_nr; i++) {
 			const struct cache_entry *ce = index_state->cache[i];
 			if (ce_stage(ce))
-				fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
-					(int)ce_namelen(ce), ce->name);
+				bug("unmerged index entry on in-memory index write: %d %.*s",
+				    ce_stage(ce), (int)ce_namelen(ce), ce->name);
 		}
-		BUG("unmerged index entries when writing inmemory index");
+		BUG_if_bug();
 	}
 
 	return lookup_tree(repo, &index_state->cache_tree->oid);
-- 
2.34.0.rc2.809.g11e21d44b24