[Development] Qt 4.8 clang and libc++

[Thiago Macieira]

On segunda-feira, 3 de setembro de 2012 08.27.43, Olivier Goffart wrote:
> > #include <utility>
> > #if defined(__clang__) && !defined(_LIBCPP_VERSION)
> > #  error "C++11 with clang requires libc++ runtime"
> > #endif
> 
> But why do we require libc++?  What's wrong with using the standard library
> from recent GCC?

Because libstdc++ contains GCC'isms and doesn't contain the Clang'isms that 
Clang requires. What's more, Clang supports certain C++11 features that GCC 
doesn't, so their Standard Library contains the matching features.

> The way to do the detection should be to include the relevant standard
> headers and check they compile fine.

That wouldn't scale. The internals of those libraries are, well, internals. 
We'd need to test every combination of libstdc++ release and patched release 
with Clang, plus the same the other way around (GCC and libc++).

That also includes future releases...

That means basically trying to compile Qt with that compiler+header 
combination to see if it works.

> Else, libc++ should probably be installed on the CI machines.

We should do that.

-- 
Thiago Macieira - thiago.macieira (AT) intel.com
  Software Architect - Intel Open Source Technology Center
     Intel Sweden AB - Registration Number: 556189-6027
     Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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