Error message formatter for range primitives

[Elronnd]

On Wednesday, 5 January 2022 at 12:32:10 UTC, Elronnd wrote:
> There's a trick I came up with, that I've been meaning to post 
> about

There is another thing I should mention: the isInputRange I 
showed is not strictly equivalent to the standard version, 
because SFIAE.  So a dispatch stage is still necessary, like with 
your method, if you want to support more than one instantiation.