Yes, in this case they are being used, that is why I corrected myself.
My mistake.
On 24/03/2026 3:44 pm, Sergey Fedorov wrote:
Well, I can be wrong about MacPorts defaults here, but from the log in
the original report shows that libc++ headers are used:
/opt/local/libexec/gcc15/libc++/include/c++/v1
Perhaps it was locally configured that way then.
In any case, my point was that the cause of the error is libc++’s
headers, not gcc as such.
On Tue, Mar 24, 2026 at 11:13 PM Chris Jones <[email protected]
<mailto:[email protected]>> wrote:
On 24/03/2026 3:02 pm, Sergey Fedorov wrote:
> To be clear: on powerpc (and by default outside of MacPorts
generally)
> gcc uses libstdc++, and that works fine.
> MacPorts uses libc++ with gcc on archs other than powerpc, which
is what
> fails. It is not a fault of gcc, it is a fault of libc++ being
outdated.
> This should work fine on 10.5 out of the box.
Wrong. By default building c++ with gcc will always link against
libstdc++, not libc++ . MacPorts GCC version have the option to use
libc++, but how well this works in practice is pretty flaky.
This is why we don't in general allow gcc as a fallback compiler for
C++
builds, as doing so would result in binaries ABI incompatble with other
binaries built with clang++. Forcing the use of gcc for this, with
configure.compiler=macports-gcc-15 is very much in-advised on any
platform where libc++ is the default runtime (i.e. all but the very
oldest ancient OSes).
Chris
