From 6da83c44ccd2f8060b7d2eb3408fc8a7b6bbd2e1 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 11:38:48 -0400
Subject: [PATCH 1/8] sum zero-arrays

---
 src/host/mapreduce.jl        |  3 +++
 test/testsuite/reductions.jl | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/src/host/mapreduce.jl b/src/host/mapreduce.jl
index cb5b489e..1be18263 100644
--- a/src/host/mapreduce.jl
+++ b/src/host/mapreduce.jl
@@ -87,6 +87,9 @@ for (fname, op) in [(:sum, :(Base.add_sum)), (:prod, :(Base.mul_prod)),
     @eval begin
         Base.$(fname!)(f::Function, r::AnyGPUArray, A::AnyGPUArray{T}) where T =
             GPUArrays.mapreducedim!(f, $(op), r, A; init=neutral_element($(op), T))
+
+        Base.$fname(r::AnyGPUArray{<:Any,0}) = @allowscalar r[]
+        Base.$fname(f::Function, r::AnyGPUArray{<:Any,0}) = f(@allowscalar r[])
     end
 end
 
diff --git a/test/testsuite/reductions.jl b/test/testsuite/reductions.jl
index a07ce04e..8874c64b 100644
--- a/test/testsuite/reductions.jl
+++ b/test/testsuite/reductions.jl
@@ -140,3 +140,20 @@ end
         @test A != B
     end
 end
+
+@testsuite "reductions/zero-arrays" AT->begin
+    @testset "$ET" for ET in supported_eltypes()
+        range = ET <: Real ? (ET(1):ET(10)) : ET
+        # sum
+        @test compare(A->sum(A), AT, reshape(rand(range, 1)))
+        @test compare(A->sum(abs, A), AT, reshape(rand(range, 1)))
+        # other functions, defined together
+        @test compare(A->prod(A), AT, reshape(rand(range, 1)))
+        @test compare(A->max(A), AT, reshape(rand(range, 1)))
+        @test compare(A->any(_->true, A), AT, reshape(rand(range, 1)))
+        @test compare(A->all(_->false, A), AT, reshape(rand(range, 1)))
+        # zero-dimensional view
+        @test compare(A->sum(A), AT, view(rand(range, 3),2))
+        @test compare(A->prod(sqrt, A), AT, view(rand(range, 3),2))
+    end
+end

From 51c25522445ca18178bb47186b28be5afe6095f4 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 12:05:03 -0400
Subject: [PATCH 2/8] max -> maximum

---
 test/testsuite/reductions.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/testsuite/reductions.jl b/test/testsuite/reductions.jl
index 8874c64b..85feb356 100644
--- a/test/testsuite/reductions.jl
+++ b/test/testsuite/reductions.jl
@@ -149,7 +149,7 @@ end
         @test compare(A->sum(abs, A), AT, reshape(rand(range, 1)))
         # other functions, defined together
         @test compare(A->prod(A), AT, reshape(rand(range, 1)))
-        @test compare(A->max(A), AT, reshape(rand(range, 1)))
+        @test compare(A->maximum(A), AT, reshape(rand(range, 1)))
         @test compare(A->any(_->true, A), AT, reshape(rand(range, 1)))
         @test compare(A->all(_->false, A), AT, reshape(rand(range, 1)))
         # zero-dimensional view

From ede96db7c00730efab22f7cf2a4ba7da57642f02 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 14:10:37 -0400
Subject: [PATCH 3/8] better way, allows init

---
 src/host/mapreduce.jl        | 6 +++---
 test/testsuite/reductions.jl | 1 +
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/host/mapreduce.jl b/src/host/mapreduce.jl
index 1be18263..fd1ff205 100644
--- a/src/host/mapreduce.jl
+++ b/src/host/mapreduce.jl
@@ -87,10 +87,10 @@ for (fname, op) in [(:sum, :(Base.add_sum)), (:prod, :(Base.mul_prod)),
     @eval begin
         Base.$(fname!)(f::Function, r::AnyGPUArray, A::AnyGPUArray{T}) where T =
             GPUArrays.mapreducedim!(f, $(op), r, A; init=neutral_element($(op), T))
-
-        Base.$fname(r::AnyGPUArray{<:Any,0}) = @allowscalar r[]
-        Base.$fname(f::Function, r::AnyGPUArray{<:Any,0}) = f(@allowscalar r[])
     end
 end
 
+Base._mapreduce_dim(f, op, init, A::AnyGPUArray{<:Any,0}, ::Colon) = op(f(@allowscalar A[]), init)
+Base._mapreduce_dim(f, op, ::Base._InitialValue, A::AnyGPUArray{<:Any,0}, ::Colon) = f(@allowscalar A[])
+
 LinearAlgebra.ishermitian(A::AbstractGPUMatrix) = mapreduce(==, &, A, adjoint(A))
diff --git a/test/testsuite/reductions.jl b/test/testsuite/reductions.jl
index 85feb356..7b8e3195 100644
--- a/test/testsuite/reductions.jl
+++ b/test/testsuite/reductions.jl
@@ -147,6 +147,7 @@ end
         # sum
         @test compare(A->sum(A), AT, reshape(rand(range, 1)))
         @test compare(A->sum(abs, A), AT, reshape(rand(range, 1)))
+        @test compare(A->sum(A, init=ET(13)), AT, reshape(rand(range, 1)))
         # other functions, defined together
         @test compare(A->prod(A), AT, reshape(rand(range, 1)))
         @test compare(A->maximum(A), AT, reshape(rand(range, 1)))

From 6bedf05e347aa1045e4efc6560a9eb4fba43b294 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 14:39:32 -0400
Subject: [PATCH 4/8] skip tests

---
 test/testsuite/reductions.jl | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/test/testsuite/reductions.jl b/test/testsuite/reductions.jl
index 7b8e3195..510085f8 100644
--- a/test/testsuite/reductions.jl
+++ b/test/testsuite/reductions.jl
@@ -147,10 +147,11 @@ end
         # sum
         @test compare(A->sum(A), AT, reshape(rand(range, 1)))
         @test compare(A->sum(abs, A), AT, reshape(rand(range, 1)))
-        @test compare(A->sum(A, init=ET(13)), AT, reshape(rand(range, 1)))
+        if VERSION >= v"1.6"
+            @test compare(A->sum(A, init=ET(13)), AT, reshape(rand(range, 1)))
+        end
         # other functions, defined together
         @test compare(A->prod(A), AT, reshape(rand(range, 1)))
-        @test compare(A->maximum(A), AT, reshape(rand(range, 1)))
         @test compare(A->any(_->true, A), AT, reshape(rand(range, 1)))
         @test compare(A->all(_->false, A), AT, reshape(rand(range, 1)))
         # zero-dimensional view

From 1a2af66cc33d3c625bc8bc237dc4f28478b26d69 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 16:28:38 -0400
Subject: [PATCH 5/8] zero-dim printing?

---
 src/host/abstractarray.jl | 2 ++
 test/testsuite/io.jl      | 4 ++++
 2 files changed, 6 insertions(+)

diff --git a/src/host/abstractarray.jl b/src/host/abstractarray.jl
index 440fa836..46a76c8c 100644
--- a/src/host/abstractarray.jl
+++ b/src/host/abstractarray.jl
@@ -55,6 +55,8 @@ Base._show_empty(io::IO, X::AnyGPUArray) =
     Base._show_empty(io, adapt(ToArray(), X))
 Base.show_vector(io::IO, v::AnyGPUArray, args...) =
     Base.show_vector(io, adapt(ToArray(), v), args...)
+Base.show_zero_dim(io::IO, X::AnyGPUArray{T, 0}) where T
+    Base.show_zero_dim(io, adapt(ToArray(), X))
 
 ## collect to CPU (discarding wrapper type)
 
diff --git a/test/testsuite/io.jl b/test/testsuite/io.jl
index 7d0c58e4..83c29f3f 100644
--- a/test/testsuite/io.jl
+++ b/test/testsuite/io.jl
@@ -30,5 +30,9 @@
         @test occursin(Regex("^1×1 Adjoint{Int64,\\s?$AT{Int64,\\s?1}}:\n 1\$"), msg) ||
             occursin(Regex("^1×1 LinearAlgebra.Adjoint{Int64,\\s?$AT{Int64,\\s?1}}:\n 1\$"), msg) ||
             occursin(Regex("^1×1 adjoint\\(::$AT{Int64,\\s?1}\\) with eltype Int64:\n 1\$"), msg)
+
+        C = AT(fill(1))
+        msg = showstr(A)
+        @test msg == "fill(1)"
     end
 end

From 4dab8d231b1953eb03ec37dd42f690de66399436 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 17:19:52 -0400
Subject: [PATCH 6/8] don't forget the = sign

---
 src/host/abstractarray.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/host/abstractarray.jl b/src/host/abstractarray.jl
index 46a76c8c..d0588e80 100644
--- a/src/host/abstractarray.jl
+++ b/src/host/abstractarray.jl
@@ -55,7 +55,7 @@ Base._show_empty(io::IO, X::AnyGPUArray) =
     Base._show_empty(io, adapt(ToArray(), X))
 Base.show_vector(io::IO, v::AnyGPUArray, args...) =
     Base.show_vector(io, adapt(ToArray(), v), args...)
-Base.show_zero_dim(io::IO, X::AnyGPUArray{T, 0}) where T
+Base.show_zero_dim(io::IO, X::AnyGPUArray{T, 0}) where T =
     Base.show_zero_dim(io, adapt(ToArray(), X))
 
 ## collect to CPU (discarding wrapper type)

From 8ded81e9f3767dffa324a4a5ce67baad87332156 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 18:13:40 -0400
Subject: [PATCH 7/8] old versions

---
 test/testsuite/io.jl | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/test/testsuite/io.jl b/test/testsuite/io.jl
index 83c29f3f..b2bd801c 100644
--- a/test/testsuite/io.jl
+++ b/test/testsuite/io.jl
@@ -33,6 +33,10 @@
 
         C = AT(fill(1))
         msg = showstr(A)
-        @test msg == "fill(1)"
+        if VERSION >= v"1.6"
+            @test msg == "fill(1)"
+        else
+            @test msg == "[1]"
+        end
     end
 end

From 3c94d3774f28a07040a65891d08ae28296453e37 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Tue, 22 Jun 2021 18:23:48 -0400
Subject: [PATCH 8/8] better bounds?

---
 test/testsuite/io.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/testsuite/io.jl b/test/testsuite/io.jl
index b2bd801c..27811f1b 100644
--- a/test/testsuite/io.jl
+++ b/test/testsuite/io.jl
@@ -33,7 +33,7 @@
 
         C = AT(fill(1))
         msg = showstr(A)
-        if VERSION >= v"1.6"
+        if VERSION >= v"1.7-"
             @test msg == "fill(1)"
         else
             @test msg == "[1]"