Re: Dropping C++03 support (again)

From: Peter Dimov (pdimov_at_[hidden])
Date: 2023-02-05 23:41:57

Andrzej Krzemienski wrote:
> Let me do a small exercise to check if I understood what is being proposed. The
> following sentences were *not* said by Peter. I am making these claims, based
> on my understanding, and I would ask you, Peter, to say if they are correct in
> the context of the proposal.
> 
> Suppose that 1.83 is the first release where the proposal is implemented.
> 
> 1. This means that the author of library Boost.X can declare "support for
> C++03 is deprecated, and it will be removed in 1.85". In 1.85 the author is
> allowed to make changes such that when library Boost.X is compiled with -
> std=C++03 a hard error is issued. This means that if library Boost.Y uses (or
> depends on) Boost.X and library Boost.Z depends on Boost.Y and The author
> of Boost.Z claims that they support C++03, this support suddenly breaks in
> library Boost.Z (because library Boost.X now issues an error on -std=C++03).

If the proposal is adopted, the author of Boost.X can remove the support for
C++03 in 1.83, without going through the deprecation procedure.

> 2. The implication of the above is that only the "leaf libraries" (those that no
> other Boost library depends on) can safely remove the C++03 support.

No, every library will be free to remove C++03 support starting with 1.83 (under
the assumption that we declare 1.82 as the last Boost release supporting C++03.)