From 32065c07e27a46d1dce42272082e7bb9aa6e6c52 Mon Sep 17 00:00:00 2001
From: MilesCranmer <miles.cranmer@gmail.com>
Date: Mon, 30 Jun 2025 00:23:48 +0100
Subject: [PATCH 1/3] only set array size when safe to do so

---
 base/array.jl | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/base/array.jl b/base/array.jl
index 61a3c39ca2bb7..a90b9a4285001 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1117,12 +1117,13 @@ function _growbeg!(a::Vector, delta::Integer)
     len = length(a)
     offset = memoryrefoffset(ref)
     newlen = len + delta
-    setfield!(a, :size, (newlen,))
     # if offset is far enough advanced to fit data in existing memory without copying
     if delta <= offset - 1
         setfield!(a, :ref, @inbounds memoryref(ref, 1 - delta))
+        setfield!(a, :size, (newlen,))
     else
         @noinline _growbeg_internal!(a, delta, len)
+        setfield!(a, :size, (newlen,))
     end
     return
 end
@@ -1172,10 +1173,10 @@ function _growend!(a::Vector, delta::Integer)
     len = length(a)
     newlen = len + delta
     offset = memoryrefoffset(ref)
-    setfield!(a, :size, (newlen,))
     newmemlen = offset + newlen - 1
     if memlen < newmemlen
         @noinline _growend_internal!(a, delta, len)
+        setfield!(a, :size, (newlen,))
     end
     return
 end
@@ -1194,7 +1195,6 @@ function _growat!(a::Vector, i::Integer, delta::Integer)
     memlen = length(mem)
     newlen = len + delta
     offset = memoryrefoffset(ref)
-    setfield!(a, :size, (newlen,))
     newmemlen = offset + newlen - 1
 
     # which side would we rather grow into?
@@ -1204,11 +1204,13 @@ function _growat!(a::Vector, i::Integer, delta::Integer)
         newref = @inbounds memoryref(mem, offset - delta)
         unsafe_copyto!(newref, ref, i)
         setfield!(a, :ref, newref)
+        setfield!(a, :size, (newlen,))
         for j in i:i+delta-1
             @inbounds _unsetindex!(a, j)
         end
     elseif !prefer_start && memlen >= newmemlen
         unsafe_copyto!(mem, offset - 1 + delta + i, mem, offset - 1 + i, len - i + 1)
+        setfield!(a, :size, (newlen,))
         for j in i:i+delta-1
             @inbounds _unsetindex!(a, j)
         end
@@ -1222,6 +1224,10 @@ function _growat!(a::Vector, i::Integer, delta::Integer)
         unsafe_copyto!(newref, ref, i-1)
         unsafe_copyto!(newmem, newoffset + delta + i - 1, mem, offset + i - 1, len - i + 1)
         setfield!(a, :ref, newref)
+        setfield!(a, :size, (newlen,))
+        for j in i:i+delta-1
+            @inbounds _unsetindex!(a, j)
+        end
     end
 end
 
@@ -1234,11 +1240,11 @@ function _deletebeg!(a::Vector, delta::Integer)
         @inbounds _unsetindex!(a, i)
     end
     newlen = len - delta
+    setfield!(a, :size, (newlen,))
     if newlen != 0 # if newlen==0 we could accidentally index past the memory
         newref = @inbounds memoryref(a.ref, delta + 1)
         setfield!(a, :ref, newref)
     end
-    setfield!(a, :size, (newlen,))
     return
 end
 function _deleteend!(a::Vector, delta::Integer)

From 6006cddc7be6f31d116562e2aeac87ebb2d017e3 Mon Sep 17 00:00:00 2001
From: MilesCranmer <miles.cranmer@gmail.com>
Date: Mon, 30 Jun 2025 00:35:16 +0100
Subject: [PATCH 2/3] fix: remove unneccessary unsetindex

---
 base/array.jl | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/base/array.jl b/base/array.jl
index a90b9a4285001..602d60c9026a6 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1225,9 +1225,6 @@ function _growat!(a::Vector, i::Integer, delta::Integer)
         unsafe_copyto!(newmem, newoffset + delta + i - 1, mem, offset + i - 1, len - i + 1)
         setfield!(a, :ref, newref)
         setfield!(a, :size, (newlen,))
-        for j in i:i+delta-1
-            @inbounds _unsetindex!(a, j)
-        end
     end
 end
 

From 87c7cdb5dbd171107b5ac7da8ad09fc8ac51e638 Mon Sep 17 00:00:00 2001
From: Miles Cranmer <miles.cranmer@gmail.com>
Date: Tue, 1 Jul 2025 04:55:44 +0900
Subject: [PATCH 3/3] ensure newlen is set

---
 base/array.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/array.jl b/base/array.jl
index 602d60c9026a6..df79d7aa96261 100644
--- a/base/array.jl
+++ b/base/array.jl
@@ -1176,8 +1176,8 @@ function _growend!(a::Vector, delta::Integer)
     newmemlen = offset + newlen - 1
     if memlen < newmemlen
         @noinline _growend_internal!(a, delta, len)
-        setfield!(a, :size, (newlen,))
     end
+    setfield!(a, :size, (newlen,))
     return
 end