Re: Does Boost.Multiprecision have a forwards declaration header?

From: John Maddock (jz.maddock_at_[hidden])
Date: 2022-12-03 18:34:27

On 03/12/2022 13:03, Ivan Matek via Boost-users wrote:
> I presume not since I could not find it in docs, but decided to double 
> check.
>
> My motivation is that I would like to limit heavy includes in my 
> header(since intrinsics for avx512 files are 20k+ LOC on my system), 
> but I would still like to use proper types in signature of my 
> functions (since none of them take .args by value fwd declarations 
> would be enough).
> So I was hoping for something like iosfwd.
>
> If it matters what part of library I am using:
> |cpp_int.hpp|
>
> P.S. I checked if telling compiler that I do not want arch support for 
> avx512 would help, but it looks like avx512 intrinsics headers are 
> included regardless, and even if it was not I would still like to not 
> get into issues when compiling for HW that supports avx512. :)

There's no such header at present, but I've just filed myself a ticket 
as it seems like a good idea to me: 
https://github.com/boostorg/multiprecision/issues/508

Note however, that with just a forward declaration you wouldn't be able 
to do anything with the type inside the function body. Would be useful 
for traits class specializations, or template function overloads which 
are not normally instantiated (as compared to int/long overloads etc) 
though.

John.