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]> 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 It is not a fault of gcc, it is a fault of libc++ being outdated.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 >
