don't copy non-diff arrays

src/compiler.jl

@@ -1199,6 +1199,9 @@ end
     if haskey(seen, prev)
         return seen[prev]
     end
+    if guaranteed_const_nongen(RT, nothing)
+        return copy_if_inactive ? Base.deepcopy_internal(prev, seen) : prev
+    end
     newa = RT(undef, size(prev))
     seen[prev] = newa
     for I in eachindex(prev)
@@ -1216,6 +1219,7 @@ end
 end
 
 
+
 @inline function EnzymeCore.make_zero(::Type{NamedTuple{A,RT}}, seen::IdDict, prev::NamedTuple{A,RT}, ::Val{copy_if_inactive}=Val(false))::NamedTuple{A,RT} where {copy_if_inactive, A,RT}
     return NamedTuple{A,RT}(EnzymeCore.make_zero(RT, seen, RT(prev), Val(copy_if_inactive)))
 end

test/runtests.jl

@@ -2350,6 +2350,11 @@ end
     @test grad.x == [3.0, 12.0]
     @test grad.p ≈ 5.545177444479562
 
+    xy = (x = [1.0, 2.0], y = [3, 4])  # y is non-diff
+    grad = Enzyme.gradient(Reverse, z -> sum(z.x .* z.y), xy)
+    @test grad.x == [3.0, 4.0]
+    @test grad.y === xy.y  # make_zero did not copy this
+
     grad = Enzyme.gradient(Reverse, z -> (z.x * z.y), (x=5.0, y=6.0))
     @test grad == (x = 6.0, y = 5.0)