MINIMAL XOR (Was: Proposal: Make Eq type class single method)

On Mon, 25 Oct 2021, Carter Schonwald wrote:

i agree with Tom and Hecate,more strongly:   https://github.com/ghc/ghc/blob/98aa29d3fe447cce3407e6864b015892244bb475/lib...  the current definition DOES NOT require defining both. 

as it currently stands, you only need to define one of '==' XOR  '/='

this actually suggests an interesting and DIFFERENT ecosystem improvement, (ignoring IEEE non-signalling NANs), namely we add support for XOR to minimal pragma syntax and issue a warning 

perhaps something like adding (XOR "reason String" clauseExpr1 clauseexpr2) ?

The problem of implementing two methods in a contradictory way arises for any OR in MINIMAL pragma, right?