refs: add function to translate errors to strings

The commit 76e760b999 (refs: introduce enum-based transaction error
types, 2025-04-08) introduced enum-based transaction error types. The
refs transaction logic was also modified to propagate these errors. For
clients of the ref transaction system, it would be beneficial to provide
human readable messages for these errors.

There is already an existing mapping in 'builtin/update-ref.c', move it
to 'refs.c' as `ref_transaction_error_msg()` and use the same within the
'builtin/update-ref.c'.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/refs.h b/refs.h
index 46a6008e07..2d58af3d88 100644
--- a/refs.h
+++ b/refs.h
@@ -908,6 +908,11 @@ void ref_transaction_for_each_rejected_update(struct ref_transaction *transactio
 					      void *cb_data);
 
 /*
+ * Translate errors to human readable error messages.
+ */
+const char *ref_transaction_error_msg(enum ref_transaction_error err);
+
+/*
  * Free `*transaction` and all associated data.
  */
 void ref_transaction_free(struct ref_transaction *transaction);