From 3d8f0cb695a5ea97ea05bc7decb19bb047cb753d Mon Sep 17 00:00:00 2001
From: voidiz <29259387+voidiz@users.noreply.github.com>
Date: Wed, 8 Nov 2023 02:23:13 +0100
Subject: [PATCH] fix(diagnostic): check if delete failed in `qf_fill_buffer()`
 (#25932)

When the contents of a quickfix buffer are replaced, there is a chance
that deletion of the previous lines fails. This ensures that we don't
get stuck in an infinite loop of retrying.

Fix #25402
---
 src/nvim/quickfix.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index 2e3cc4f170..61157301b6 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -4135,7 +4135,12 @@ static void qf_fill_buffer(qf_list_T *qfl, buf_T *buf, qfline_T *old_last, int q
 
     // delete all existing lines
     while ((curbuf->b_ml.ml_flags & ML_EMPTY) == 0) {
-      (void)ml_delete((linenr_T)1, false);
+      // If deletion fails, this loop may run forever, so
+      // signal error and return.
+      if (ml_delete((linenr_T)1, false) == FAIL) {
+        internal_error("qf_fill_buffer()");
+        return;
+      }
     }
   }