From 770b1a645b87d0c43035c5bce2dd906474588e94 Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Tue, 19 Jan 2021 13:19:10 -0600
Subject: [PATCH] Preserve input type for unaliascopy(::ReinterpretArray)
 (#39316)

---
 base/reinterpretarray.jl | 3 ++-
 test/reinterpretarray.jl | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/base/reinterpretarray.jl b/base/reinterpretarray.jl
index b5f13ed113f15..e2990bafcd086 100644
--- a/base/reinterpretarray.jl
+++ b/base/reinterpretarray.jl
@@ -278,7 +278,8 @@ eachindex(style::IndexSCartesian2, A::AbstractArray) = eachindex(style, parent(A
 
 parent(a::ReinterpretArray) = a.parent
 dataids(a::ReinterpretArray) = dataids(a.parent)
-unaliascopy(a::ReinterpretArray{T}) where {T} = reinterpret(T, unaliascopy(a.parent))
+unaliascopy(a::NonReshapedReinterpretArray{T}) where {T} = reinterpret(T, unaliascopy(a.parent))
+unaliascopy(a::ReshapedReinterpretArray{T}) where {T} = reinterpret(reshape, T, unaliascopy(a.parent))
 
 function size(a::NonReshapedReinterpretArray{T,N,S} where {N}) where {T,S}
     psize = size(a.parent)
diff --git a/test/reinterpretarray.jl b/test/reinterpretarray.jl
index 564aac5993cd7..a8cadd83c3dec 100644
--- a/test/reinterpretarray.jl
+++ b/test/reinterpretarray.jl
@@ -368,3 +368,11 @@ ars = reinterpret(reshape, Int, a)
     @test as isa TSlow{NTuple{4,Float64},1}
     @test size(as) == (4,)
 end
+
+
+@testset "aliasing" begin
+    a = reinterpret(NTuple{2,Float64}, rand(Float64, 4, 4))
+    @test typeof(Base.unaliascopy(a)) === typeof(a)
+    a = reinterpret(reshape, NTuple{4,Float64}, rand(Float64, 4, 4))
+    @test typeof(Base.unaliascopy(a)) === typeof(a)
+end