[cfe-dev] [llvm-dev] Upcoming removal of std::auto_ptr (in C++1z)

[Eric Fiselier via cfe-dev]

On Mon, Jan 30, 2017 at 3:35 PM, Martin J. O'Riordan <
martin.oriordan at movidius.com> wrote:

> Thanks Eric, the assurance that there will never be a need for a MultiLib
> build is more comforting than you might guess J, and to me, it is further
> weight against the incumbent.
>

It would be really unfortunate if different dylibs were needed for
different dialects. :-)


>
> So from that, I would like to expand - with an out-of-tree - CMake
> “incompatible” library cross-compiler, what flags should I pass while
> building LibC++?  Usually I follow whatever ‘buildit’ recommends, but ‘
> buildit’ looks likely to be removed soon.
>

That's unfortunate that you can't use the CMake build. The reason buildit
is getting removed is it is unmaintained, so it's "recommendations" are way
out of date. I would suggest configuring CMake with a "compatible compiler"
as closely as possible to your real build, and then simply inspect the
flags it passes. Off the top of my head the important compile flags are:

-nostdinc++
-D_LIBCPP_BUILDING_LIBRARY
-DLIBCXX_BUILDING_LIBCXXABI (Assuming your building against libc++abi).

The linker flags are much more complex, so I won't attempt to enumerate the
possibilities here.

/Eric

>
>
> Thanks,
>
>
>
>             MartinO
>
>
>
>
>
> *From:* Eric Fiselier [mailto:eric at efcs.ca]
> *Sent:* 30 January 2017 17:20
> *To:* Martin J. O'Riordan <martin.oriordan at movidius.com>
> *Cc:* Marshall Clow <mclow.lists at gmail.com>; cfe-dev <
> cfe-dev at lists.llvm.org>
> *Subject:* Re: [cfe-dev] [llvm-dev] Upcoming removal of std::auto_ptr (in
> C++1z)
>
>
>
>
>
>
>
> On Wed, Jan 25, 2017 at 2:11 AM, Martin J. O'Riordan via cfe-dev <
> cfe-dev at lists.llvm.org> wrote:
>
> Will LibC++ still enable ‘auto_ptr’ when ‘-std=c++[98|11|15]’ are
> chosen?  I assume that it will.  If ‘auto_ptr’ is entirely in the
> headers, I don’t see any problems, but if some support is in the library,
> how should the library itself be built so that a single library build
> supports all of the Standards?  Will we need to provide Multilib builds of
> the libraries for C++17 versus its predecessors?
>
>
>
>
>
> There will never be a need for multilib builds of Libc++ for different
> dialects.
>
>
>
> /Eric
>
>
>
>
>
>
>
> Thanks,
>
>
>
>             MartinO
>
>
>
> *From:* llvm-dev [mailto:llvm-dev-bounces at lists.llvm.org] *On Behalf Of *Marshall
> Clow via llvm-dev
> *Sent:* 24 January 2017 22:34
> *To:* llvm-dev at lists.llvm.org
> *Subject:* Re: [llvm-dev] Upcoming removal of std::auto_ptr (in C++1z)
>
>
>
>
>
>
>
> On Mon, Jan 23, 2017 at 1:32 PM, Marshall Clow <mclow.lists at gmail.com>
> wrote:
>
> The upcoming C++1z (probably C++17) standard will not contain several
> things - most notably auto_ptr.
>
>
>
> Soon, libc++ will not be providing auto_ptr by default when building in
> C++1z mode.
>
> You'll be able to get it back with a
>
> "-D_LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" on your command line, or
> "#define _LIBCPP_ENABLE_CXX17_REMOVED_AUTO_PTR" before including any
> libc++ header files.
>
>
>
>
>
> Landed as revision 292986.
>
>
>
> -- Marshall
>
>
>
>
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