From ad282d75fbdd1452205ee164f06bd06497d4b058 Mon Sep 17 00:00:00 2001
From: Michael Abbott <32575566+mcabbott@users.noreply.github.com>
Date: Thu, 6 May 2021 21:01:42 -0400
Subject: [PATCH] tests pass, only real

---
 src/rulesets/Base/mapreduce.jl  |  4 ++--
 test/rulesets/Base/mapreduce.jl | 13 ++++++++-----
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/rulesets/Base/mapreduce.jl b/src/rulesets/Base/mapreduce.jl
index 5b3e713be..0a7330b15 100644
--- a/src/rulesets/Base/mapreduce.jl
+++ b/src/rulesets/Base/mapreduce.jl
@@ -82,7 +82,7 @@ end
 
 function ∇prod_dims(dims, x, dy, y=prod(x; dims=dims))
     T = promote_type(eltype(x), eltype(dy))
-    dx = fill!(similar(x, T, size(x)), zero(T))
+    dx = fill!(similar(x, T, axes(x)), zero(T))
     ∇prod_dims!(dx, dims, x, dy, y)
     return dx
 end
@@ -102,7 +102,7 @@ end
 
 function ∇prod(x, dy::Number=1, y::Number=prod(x))
     T = promote_type(eltype(x), eltype(dy))
-    dx = fill!(similar(x, T, size(x)), zero(T))
+    dx = fill!(similar(x, T, axes(x)), zero(T)) # axes(x) makes MArray on StaticArrays, Array for structured matrices
     ∇prod!(dx, x, dy, y)
     return dx
 end
diff --git a/test/rulesets/Base/mapreduce.jl b/test/rulesets/Base/mapreduce.jl
index 2a1ae87fe..ef34b3e0f 100644
--- a/test/rulesets/Base/mapreduce.jl
+++ b/test/rulesets/Base/mapreduce.jl
@@ -43,18 +43,18 @@
                     test_rrule(prod, xp ⊢ xpbar; fkwargs=(dims=dims,), check_inferred=true)
                 end
             end
-            
-            @testset "structured" begin
+
+            @testset "structured wrappers" begin
                 # Adjoint -- like PermutedDimsArray this may actually be used
                 xa = adjoint(rand(T,4,4))
                 test_rrule(prod, xa ⊢ rand(T,4,4))
                 @test_skip test_rrule(prod, xa ⊢ rand(T,4,4), fkwargs=(dims=2,)) # seems broken?
 #=
-xa = rand(3,3)'
+xa = randn(3,3)'
 Zygote.gradient(x -> sum(prod(x,dims=1)), xa)[1]
 ForwardDiff.gradient(x -> sum(prod(x,dims=1)), xa)
 Zygote.gradient(x -> sum(prod(x,dims=1)), Matrix(xa))[1]
-# These all agree, so the fault is in the testing, somehow. No doubt I'm holding it wrong.
+# These all agree, so the fault is in the testing, somehow.
 =#
                 @test unthunk(rrule(prod, adjoint(rand(T,3,3)))[2](1.0)[2]) isa Matrix
                 @test unthunk(rrule(prod, adjoint(rand(T,3,3)), dims=1)[2](ones(1,3))[2]) isa Matrix
@@ -71,10 +71,13 @@ Zygote.gradient(x -> sum(prod(x,dims=1)), Matrix(xa))[1]
                 @test_skip test_rrule(prod, xs ⊢ rand(T,4,4))
                 @test_skip test_rrule(prod, xs ⊢ rand(T,4,4), fkwargs=(dims=2,))
 #=
-xs = Symmetric(rand(3,3))
+xs = Symmetric(100randn(3,3))
 Zygote.gradient(x -> sum(prod(x,dims=1)), xs)[1]
 ForwardDiff.gradient(x -> sum(prod(x,dims=1)), Matrix(xs))
 Zygote.gradient(x -> sum(prod(x,dims=1)), Matrix(xs))[1]
+# These all agree. This time test_rrule, besides an error, gives a complaint that aa ≈ bb fails, where:
+aa, bb = [19520.328243416912 -10637.452753538959 10525.400561900045; -2510.9032814879456 -3998.8778331597046 -9169.556884964955; 635.6849617151897 -2346.1691173613817 1445.40000910585], [19520.32824346742 -13148.35603493111 11161.0855235898; -13148.35603493111 -3998.877833179008 -11515.726002337731; 11161.0855235898 -11515.726002337731 1445.4000090979655]
+bb ≈ (aa .+ aa') .- Diagonal(aa)  # not quite a projection. Is that right?
 =#
                 @test unthunk(rrule(prod, Symmetric(rand(T,3,3)))[2](1.0)[2]) isa Matrix
             end