[cfe-dev] Control selected GCC installation / selected libstdc++ version?

[don hinton via cfe-dev]

Try passing -DGCC_INSTALL_PREFIX to cmake.  You can grep the config files
to see how it's used.

hth... don
On Mar 10, 2016 9:54 AM, "Kevin Funk via cfe-dev" <cfe-dev at lists.llvm.org>
wrote:

> On Saturday, March 5, 2016 4:07:43 PM CET Kevin Funk via cfe-dev wrote:
> > Heya,
> >
> > I just installed GCC6 on my system (which obviously comes with a new
> > libstdc+ +), and this, unfortunately, breaks Clang.
> >
> > Long story short: In this particular case I can't build LLVM anymore,
> since
> > clang errors out:
> >
> > /usr/bin/../lib/gcc/x86_64-linux-gnu/6.0.0/../../../../include/c++/6.0.0/
> > tuple:1381:14: error: no matching constructor for initialization of
> > 'tuple<llvm::LexicalScope *&&, const llvm::DILocalScope *&&, nullptr_t
> &&,
> > bool &&>'
> >     { return tuple<_Elements&&...>(std::forward<_Elements>(__args)...); }
> >              ^                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > ...
> >
> >
> > I'm not interested in solving the error, I'm more concerned about this:
> Is
> > it possible to force Clang into using a specific libstdc++ version? Right
> > now it seems to just choose the highest version available(?)
> >
> > # clang++-3.6 -E -v
> > Ubuntu clang version 3.6.2-3ubuntu1 (tags/RELEASE_362/final) (based on
> LLVM
> > 3.6.2)
> > Target: x86_64-pc-linux-gnu
> > Thread model: posix
> > (snip)
> > Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.3
> > Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.1
> > Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.0.0
> > Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.0.0
> > Candidate multilib: .;@m64
> > Selected multilib: .;@m64
> >
> > ^ How can I force clang to use /usr/lib/gcc/x86_64-linux-gnu/5.3.1
> instead,
> > for instance?
> >
> > Is that even possible? I had a brief look at tools/clang/lib/Driver/
> > ToolChains.cpp, but couldn't find any knobs I could use from the
> > command-line.
>
> Bump.
>
> Any idea? Am I missing something?
>
> Do you a think a patch which introduces an env var setting for specifying
> the
> desired libstdc++ version would be acceptable?
>
> Cheers,
> Kevin
>
> > Cheers,
> > Kevin
>
>
> --
> Kevin Funk | kfunk at kde.org | http://kfunk.org
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>
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