Re: Unconditional conditional building is cursed

From: Peter Dimov (pdimov_at_[hidden])
Date: 2021-08-26 20:11:50

Nikita Kniazev wrote:
> Some libraries (Context, Contract, Fiber, Json, Math, Nowide) are built
> conditionally and use checks from the Config library to do that (`import
> ../../config/checks/config : requires ;`). Apparently, it happens to be a
> PITA for some consumers. Vcpkg had to hack around that and update the hack
> every Boost release, but Boost 1.76 revealed problems in it (
> https://github.com/boostorg/build/issues/724) and Boost 1.77 is blocked by
> it (https://github.com/microsoft/vcpkg/pull/19556#issuecomment-
> 904702798).
> 
> I have a mixed feeling about silently not building libraries. I understand
> that for a lot of people it is reasonable that the default stage build will
> not build a library on an unsupported compiler. However, it is absolutely
> bad and a confusing thing to a user that the input is silently ignored when
> a library is requested using the `--with-<library>` flag.

But the problem has nothing to do with silently not building libraries. It's
caused by libraries assuming that Boost.Config is at ../config.