'version'-based code selection

[Yatheendra]

On Saturday, 1 June 2019 at 07:46:40 UTC, Jonathan M Davis wrote:
>
> Like static ifs, version statements are completely a 
> compile-time construct and having nothing to do with runtime 
> beyond how they affect the code that's generated.
> ...
> - Jonathan M Davis

Thanks for taking the time.

That's it then for selecting between malloc/free implementations 
at runtime (program start-up time, usually) in such a way. There 
might still be hope in the form of a separate dynamic library 
with re-implemented malloc, and equivalent wrapper API's around 
libc in another library (whole program, including Phobos, relying 
on the same malloc library).