alt Hacker NewsNo, concepts interoperate with templates. I guess if you consider duck typing to be a feature, then using concepts can put constraints on that, but that is literally the purpose of them and nobody makes you use them.
If you aren't instantiating a template, then it isn't used, so who cares if it has theoretical errors to be figured out later? This behavior is in fact used to decide between alternative template specializations for the same template. Concepts do it better in some ways.
> If you aren't instantiating a template, then it isn't used, so who cares if it has theoretical errors to be figured out later?
Just because you aren't instantiating a template a particular way doesn't necessarily mean no one is instantiating a template a particular way.
A big concern here would be accidentally depending on something that isn't declared in the concept, which can result in a downstream consumer who otherwise satisfies the concept being unable to use the template. You also don't get nicer error messages in these cases since as far as concepts are concerned nothing is wrong.
It's a tradeoff, as usual. You get more flexibility but get fewer guarantees in return.