From f611b46e72c788c016933033dfadee6a9e138d47 Mon Sep 17 00:00:00 2001
From: Matt Bauman <mbauman@gmail.com>
Date: Wed, 20 Mar 2019 10:57:26 -0400
Subject: [PATCH] Fix 29545: Implement unaliascopy for ReinterpretArray
 (#30296)

* Fix 29545: Implement unaliascopy for ReinterpretArray
---
 base/reinterpretarray.jl |  1 +
 test/reinterpretarray.jl | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/base/reinterpretarray.jl b/base/reinterpretarray.jl
index 4a156d11d1cf5..fa2af7a20af10 100644
--- a/base/reinterpretarray.jl
+++ b/base/reinterpretarray.jl
@@ -96,6 +96,7 @@ IndexStyle(a::ReinterpretArray) = IndexStyle(a.parent)
 
 parent(a::ReinterpretArray) = a.parent
 dataids(a::ReinterpretArray) = dataids(a.parent)
+unaliascopy(a::ReinterpretArray{T}) where {T} = reinterpret(T, unaliascopy(a.parent))
 
 function size(a::ReinterpretArray{T,N,S} where {N}) where {T,S}
     psize = size(a.parent)
diff --git a/test/reinterpretarray.jl b/test/reinterpretarray.jl
index 6a52fa8b0b098..0247f03a4d644 100644
--- a/test/reinterpretarray.jl
+++ b/test/reinterpretarray.jl
@@ -182,6 +182,16 @@ let a = [0.1 0.2; 0.3 0.4], at = reshape([(i,i+1) for i = 1:2:8], 2, 2)
     @test r == OffsetArray(reshape(1:8, 2, 2, 2), (0, offsetvt...))
 end
 
+@testset "potentially aliased copies" begin
+    buffer = UInt8[1,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0]
+    mid = length(buffer) ÷ 2
+    x1 = reinterpret(Int64, @view buffer[1:mid])
+    x2 = reinterpret(Int64, @view buffer[mid+1:end])
+    x1 .= x2
+    @test x1 == x2 == [2]
+    @test x1[] === x2[] === Int64(2)
+end
+
 # Test 0-dimensional Arrays
 A = zeros(UInt32)
 B = reinterpret(Int32,A)