Return values from auto function

[gbram]

On Friday, 6 November 2020 at 12:03:01 UTC, Paul Backus wrote:
> On Friday, 6 November 2020 at 10:51:20 UTC, Andrey Zherikov 
> wrote:
>>
>> How can I make the original code compilable without 
>> templatizing `failure` function?
>
> You can't. Both return values have to have the same type, which 
> means the failure function has to be able to return more than 
> one type, which means it has to be a template.

Being pedantic, he can, by templatising 'f' instead.