Re: Opinions on introduction of string_view in Core

From: Peter Dimov (pdimov_at_[hidden])
Date: 2021-10-19 12:27:39

Rainer Deyke wrote:
> On 19.10.21 08:26, Gavin Lambert via Boost wrote:
> > Header-only does not avoid ABI ODR problems.  It just moves where they
> > occur (which in some ways makes them a lot worse than built libraries).
> 
> ODR violations can be prevented with namespace aliases.
> 
> #if __cplusplus >= 201703L
> #define BOOST_JSON_NAMESPACE json_with_std_string_view
> namespace BOOST_JSON_NAMESPACE {
>    using string_view = std::string_view;
> }
...

JSON already does that for its "standalone" mode, to support linking
"Boost" and "standalone" JSON in the same application because of
user demand.

> That said, compiling parts of the same program with different C++
> standards is asking for trouble.  I would expect ODR violations from the
> standard library in that case.

People do that every day, sometimes without even realizing it.