From ad1f3849bde2b2448c0cb281bdf425d63693b532 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bogumi=C5=82=20Kami=C5=84ski?= <bkamins@sgh.waw.pl>
Date: Sat, 30 Apr 2022 09:31:00 +0200
Subject: [PATCH] Fix copyto! with #undef

---
 src/PooledArrays.jl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/PooledArrays.jl b/src/PooledArrays.jl
index 7daf2b9..2760247 100644
--- a/src/PooledArrays.jl
+++ b/src/PooledArrays.jl
@@ -279,7 +279,11 @@ function Base.copyto!(dest::PooledArrOrSub{T, N, R}, doffs::Union{Signed, Unsign
         copyto!(DataAPI.refarray(dest), doffs, DataAPI.refarray(src), soffs, n)
     else
         @inbounds for i in 0:n-1
-            dest[doffs+i] = src[soffs+i]
+            if iszero(src[soffs+i])
+                dest.refs[doffs+i] = zero(eltype(dest.refs))
+            else
+                dest[doffs+i] = src[soffs+i]
+            end
         end
     end
     return dest