Re: Suggested policy for dropping C++03 support in Boost libraries

From: Robert Ramey (ramey_at_[hidden])
Date: 2019-11-08 12:42:53

On 11/8/19 3:44 AM, Rainer Deyke via Boost wrote:
> On 07.11.19 22:42, Rob Stewart via Boost wrote:
>> Consider the alternate path of bumping the major version. There are a 
>> lot of libraries that will have to drop 03 simultaneously,

Hmmm - I'm not seeing this this.

  so that
>> would be signified clearly by a move to Boost v2.

So I'm not seeing that changing to 1 -> 2 would signify anything.

> 1. It lets us point to a definite last version of Boost to support 
> C++03.  Have a project that is stuck on C++03, but compiles with the 
> current latest version of Boost?  This is the specific version of Boost 
> that you should use.

I don't see this either.  I'm sure that any library which works with 
C++03 will work with C++20.  In fact, given that C++ purports to support 
ABI compatibility, one should be able to compile each source file with 
different C++ version switches.

> 
> 2. It leaves open the door for an emergency maintenance release to the 
> C++03 line, in case any truly terrible bugs end up in that final 1.x 
> release.

I think that door is already open.

And of course, given the backward source and binary compatibility 
presumably guaranteed by C++ the whole effort is pointless and will 
confuse some people into thinking that these C++ features don't exist.

Having said this, I would expect that someday in the future, C++ will 
drop and/or modify requirements for one or both of backward source 
compatibility and ABI stability due to the burden that these place on 
the evolution of the language.  At that point, one might think of 
changing boost 1.xx to 2.xx. But that day is not yet here.  So the 
concerns raised here are premature.

Robert Ramey