Clarify deprecation of ^^^

[QuinnWilton]

Hello! In Elixir 1.12, ^^^ began outputting a deprecation warning:

iex(1)> import Bitwise
Bitwise
iex(2)> 3 ^^^ 5
warning: ^^^ is deprecated. It is typically used as xor but it has the wrong precedence, use Bitwise.bxor/2 instead
  iex:2:3

6

It isn't clear to me whether this warning is meant to indicate that ^^^ is deprecated entirely, or just in its use as a delegate for Bitwise.bxor/2. The fact that it calls out Bitwise.bxor/2 specifically makes me think that the deprecation is limited to that use, but the warning is output in all cases:

iex(1)> defmodule Operator do 
...(1)> import Kernel, except: [^^^: 2]
...(1)> def a ^^^ b, do: a + b
...(1)> end
warning: ^^^ is deprecated. It is typically used as xor but it has the wrong precedence, use Bitwise.bxor/2 instead
  iex:3:7

{:module, Operator,
 <<70, 79, 82, 49, 0, 0, 4, 248, 66, 69, 65, 77, 65, 116, 85, 56, 0, 0, 0, 140,
   0, 0, 0, 15, 15, 69, 108, 105, 120, 105, 114, 46, 79, 112, 101, 114, 97, 116,
   111, 114, 8, 95, 95, 105, 110, 102, 111, ...>>, {:^^^, 2}}
iex(2)> import Operator
Operator
iex(3)> 5 ^^^ 3
8
iex(4)> warning: ^^^ is deprecated. It is typically used as xor but it has the wrong precedence, use Bitwise.bxor/2 instead
  iex:3:3

nil
iex(5)> 

Note, also, that in the last snippet the warning is output after the result of the expression is printed, causing it to be rendered as part of the prompt for iex(4)>

I suppose my question is: is ^^^ going to be removed entirely in Elixir 2.0.0, and if so, should the warning be updated to reflect that more clearly?

[whatyouhide]

@QuinnWilton let's wait for José but I'm pretty sure ^^^ is only deprecated as an alias for Bitwise.bxor/2 since it's gonna be in the operators list anyways. I agree that if that's the case we could improve the warning, thanks for reporting 💟

[josevalim]

The operator will change precedence in Elixir v2.0.0 but not be removed. So my advice is to consider it as if it will be removed as the precedence change may break code.

[QuinnWilton]

That makes sense, thank you!