clang-3.4 not picking up C++11 headers on 10.6.8

[RJVB (René Bertin)]

Is this a known issue? When building the QtCurve 1.8.18 port, clang++-mp-3.4 -std=c++11 will pick up a version of #include <utility> that apparently does not define std::forward ... There *is* a utility header in llvm-3.4's install tree (in a "v1" subdirectory), but it's not being found.

In other words, macports-clang-3.4 cannot be used to build C++11 projects on OS X 10.6.8, not even with -std=c++0x. Apple's version, basically the same compiler, works fine for those projects on 10.9 .

[RJVB (René Bertin)]

NB: this is becoming an issue now that more and more KDE ports require C++11, and have to be built using a manual compiler specification to use macports-gcc-4.8 . And that makes unattended port upgrade outdated runs neigh impossible.

[RJVB (René Bertin)]

example: full log of failed build of port:akonadi 1.13.0

[jmroot (Joshua Root)]

There’s your problem:

CXXFLAGS='-Os -arch x86_64 -stdlib=libstdc++’

You need -stdlib=libc++ to use C++11.

[NicosPavlov]

Duplicate of #45300.

[RJVB (René Bertin)]

Replying to jmr@…:

You need -stdlib=libc++ to use C++11.

On 10.8 or 10.9 and higher, yes. 10.6.8 doesn't have libc++ (and gcc-mp-4.8 does fine without it).

Besides, the issue at hand is a compilation issue, not a linker issue (which could have been addressed with -stdlib=libc++).

[RJVB (René Bertin)]

Replying to nicos@…:

Duplicate of #45300.

Actually, #45300 is a result of this .... and having closed the ticket might mean the clang maintainer(s) aren't going to address the underlying issue :-/

[jeremyhu (Jeremy Huddleston Sequoia)]

10.6.8 doesn't have libc++

That's why you need to install it via the libcxx port.

(and gcc-mp-4.8 does fine without it).

That's because gcc-mp-4.8 is using libstdcxx or libstdcxx-devel depending on which port you installed.

There is no underlying issue. You need to use libc++ for C++11 with clang. There is no intention of supporting libstdc++ for C++11 in clang.

[RJVB (René Bertin)]

I recall why I don't have libcxx installed: it has a build depency on clang-3.3 ..

Will installing port:libcxx and port:libcxxabi (mostly containing libraries) address the issue of clang-3.4 not finding the correct headerfiles?

There is no intention of supporting libstdc++ for C++11 in clang.

I'm a bit at a loss here. That support is there on Linux, and should be platform-agnostic, no?

[jeremyhu (Jeremy Huddleston Sequoia)]

Replying to rjvbertin@…:

I recall why I don't have libcxx installed: it has a build depency on clang-3.3 ..

Will installing port:libcxx and port:libcxxabi (mostly containing libraries) address the issue of clang-3.4 not finding the correct headerfiles?

Yes, assuming you use -stdlib=libc++ as well

There is no intention of supporting libstdc++ for C++11 in clang.

I'm a bit at a loss here. That support is there on Linux, and should be platform-agnostic, no?

The clang compilers will only use the C++ runtimes in /usr/lib. There is no intention of supporting other C++ runtimes due to the huge can of worms that opens up. Going forward, MacPorts should only support libc++ on new platforms, and we have a way for users on SnowLeopard through Mountain Lion to also use libc++.

[RJVB (René Bertin)]

Replying to jeremyhu@…:

Will installing port:libcxx and port:libcxxabi (mostly containing libraries) address the issue of clang-3.4 not finding the correct headerfiles?

Yes, assuming you use -stdlib=libc++ as well

Can one have port:libcxx and port:libcxxabi installed and activated without interference with existing binaries or builds as long as one does NOT use -stdlib=libc++, on 10.6?

The clang compilers will only use the C++ runtimes in /usr/lib. There is no intention of supporting other C++ runtimes

It seems it shouldn't be that hard to create a backwards compatible updated libstdc++ that can replace the one in /usr/lib, but priorities are priorities ...

we have a way for users on SnowLeopard through Mountain Lion to also use libc++.

One that requires rebuilding all binaries that contain compiled C++ code, right?

Maybe that could be an automatic process comparable to +universal ... but backed up by the build bots? Still a huge pile of work, esp. with clang-mp-3.4 being as slow as it is ...

[jeremyhu (Jeremy Huddleston Sequoia)]

Replying to rjvbertin@…:

Replying to jeremyhu@…:

Will installing port:libcxx and port:libcxxabi (mostly containing libraries) address the issue of clang-3.4 not finding the correct headerfiles?

Yes, assuming you use -stdlib=libc++ as well

Can one have port:libcxx and port:libcxxabi installed and activated without interference with existing binaries or builds as long as one does NOT use -stdlib=libc++, on 10.6?

Of course. If you don't use -stdlib=libc++, clang will use libstdc++ on Snow Leopard.

The clang compilers will only use the C++ runtimes in /usr/lib. There is no intention of supporting other C++ runtimes

It seems it shouldn't be that hard to create a backwards compatible updated libstdc++ that can replace the one in /usr/lib, but priorities are priorities ...

It actually is not only difficult but license-restrictive.

we have a way for users on SnowLeopard through Mountain Lion to also use libc++.

One that requires rebuilding all binaries that contain compiled C++ code, right?

Yes.

Maybe that could be an automatic process comparable to +universal ... but backed up by the build bots? Still a huge pile of work, esp. with clang-mp-3.4 being as slow as it is ...

That was discussed a few months ago.

[bitpup]

Cc Me!