In-place broadcast composed with other operations is allocating

[dcabecinhas]

If f is just assignment a .= b then it doesn't allocate but if composed with + or * it does.

using ComponentArrays
using BenchmarkTools

a = rand(3)
b = rand(3)
c = ComponentArray(a = rand(3))
d = ComponentArray(a = rand(3))

function f(a,b)
           a .+= b
end

@btime f($a,$b);
#  15.156 ns (0 allocations: 0 bytes)

@btime f($c,$d);
#  42.662 ns (1 allocation: 112 bytes)

@btime f($a,$c);
#  15.188 ns (0 allocations: 0 bytes)

@btime f($c,$a);
#  42.043 ns (1 allocation: 112 bytes)

[jonniedie]

Hmm. That shouldn't be happening. Thanks for the issue, I'll take a look.