multiple ports with stdlibc++ mismatches (all on 10.13)...

[Joshua Root]

On 2018-6-1 07:24 , iEFdev wrote:
> 
> I made a quick test on flac, adding:
> 
> # flac is using libstdc++ (this installation is configured to use libc++)
> configure.cxx_stdlib libstdc++
> 
> …and the rev-upgrade let it pass.
> 
>> Please open tickets or better yet PRs for affected ports.
>>
>> - Josh
> 
> Since I'm on an older system, with libcxx set in my config files -
> wouldn't a ticket be a better option in case this is a no-error? Perhaps
> it should be wrapped around a check for what macos version, etc?
> 
> When searching I saw this one (non-related):
> https://lists.macports.org/pipermail/macports-dev/2015-April/030230.html
> 
> So perhaps something like:
> 
> if {[string equal ${configure.cxx_stdlib} "libc++"]} {
>     configure.cxx_stdlib libstdc++
> }
> 
> Would that be a better approach?

Unfortunately using a different stdlib than the system-wide choice is
not an option for flac, as it provides libFLAC++ which is used by other
things. All C++ programs need to be using the same stdlib as all the C++
libraries they use, so effectively all C++ libraries have to use the
system-wide stdlib (as set in macports.conf in your case, but it's
equally true if the stdlib was auto-selected based on the platform).

Programs that are written in C++ but don't use or export any C++
libraries can get away with using a different stdlib.

If you don't happen to have anything installed that uses libFLAC++, you
of course won't see the problems resulting from a stdlib mismatch there.

- Josh