Re: Opinions on introduction of string_view in Core

From: Rainer Deyke (rdeyke_at_[hidden])
Date: 2021-10-19 11:12:50

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;
}
#else
#define BOOST_JSON_NAMESPACE json_with_boost_string_view
namespace BOOST_JSON_NAMESPACE {
   using string_view = boost::string_view;
}
#endif

using json = BOOST_JSON_NAMESPACE;
namespace BOOST_JSON_NAMESPACE {
   // Library contents go here.
}

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.

-- 
Rainer Deyke (rainerd_at_[hidden])