[Nix-dev] NEWBYE question: why clang-3.7 ships cpp?

[Christophe Trophime]

Christophe TROPHIME 
Research Engineer 

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M at il : christophe.trophime at lncmi.cnrs.fr 

----- Original Message -----
> From: "Fabian Schmitthenner" <nix-dev at schmitthenner.eu>
> To: nix-dev at lists.science.uu.nl
> Sent: Thursday, March 24, 2016 5:10:43 PM
> Subject: Re: [Nix-dev] NEWBYE question: why clang-3.7 ships cpp?
> 
> 
> 
> On 03/24/2016 04:00 PM, Christophe Trophime wrote:
> > ----- Original Message -----
> >> From: "Vladimír Čunát" <vcunat at gmail.com>
> >> To: "Christophe Trophime" <christophe.trophime at lncmi.cnrs.fr>
> >> Cc: nix-dev at lists.science.uu.nl
> >> Sent: Wednesday, March 23, 2016 10:56:12 AM
> >> Subject: Re: [Nix-dev] NEWBYE question: why clang-3.7 ships cpp?
> >>
> >> On 03/23/2016 10:53 AM, Christophe Trophime wrote:
> >>> You mean that I can install clang and gcc provided I do something like
> >>> that:
> >>> nix-env --set-flag priority 5 binutils
> >>> nix-env --set-flag priority 10 gcc
> >>> nix-env --set-flag priority 20 clang
> >> Yes. Note that you can set the priority of a package by this interface
> >> only *after* installing it... so you need to do it one-by-one in case
> >> they refuse to install due to collisions.
> >>
> > Thanks. Now I have gcc and clang side by side great
> > nix-env -q:
> > clang-wrapper-3.7.1
> > cln-1.3.4
> > cmake-3.4.0
> > eigen-3.2.5
> > flex-2.6.0
> > gcc-wrapper-4.9.3
> > gfortran-wrapper-4.9.3
> > ...
> >
> > Fine but when I tried to compile my actual application based on Feelpp
> > which rebuilds for its own google-gflags and glog I end up with the
> > following error when building with clang 3.7:
> > -- Glog first pass: GLOG_INCLUDE_DIR-NOTFOUND
> > -- Building glog in
> > /home/trophime/feelpp_build/clang-3.7/contrib/glog-compile...
> > --    - using gflags
> > /home/trophime/feelpp_build/clang-3.7/contrib/gflags/...
> > -- Installing glog in /home/trophime/feelpp_build/clang-3.7/contrib/glog...
> > In file included from
> > /home/trophime/github/feelpp/contrib/glog/src/stl_logging_unittest.cc:34:
> > In file included from ./src/glog/stl_logging.h:54:
> > /nix/store/5idnvskkm4hky2fj335xfbqpfim3g9pd-gcc-4.9.3/include/c++/4.9.3/ext/hash_set:60:10:
> > fatal error: 'backward_warning.h' file not found
> > #include "backward_warning.h"
> >          ^
> > 1 error generated.
> >
> > I suspect that this is connected with the way clang has been build...
> > How can I tell which gcc/g++ has been used for building this version? is it
> > gcc 4.9.3 or an older one?
> >
> > What if I want to rebuild clang?
> > I tried
> > nix-build -check -A clang but I only says:
> >  checking path(s)
> >  ‘/nix/store/i47yln3r5a89wp0gza9nv7zla5xim714-clang-wrapper-3.7.1’
> > warning: rewriting hashes in
> > ‘/nix/store/i47yln3r5a89wp0gza9nv7zla5xim714-clang-wrapper-3.7.1’; cross
> > fingers
> > /nix/store/i47yln3r5a89wp0gza9nv7zla5xim714-clang-wrapper-3.7.1
> The nix way of doing this is to use nix-shell instead of installing gcc
> and clang.
> Just do
> 
> $ nix-shell -p clang cmake eigen flex
> 
> (of cause adjust to your needed packages)
> This opens a shell with the packages available. Then you can compile
> your application.
> If this works for you, create a shell.nix or default.nix file with the
> following content:
> 
> ``
> { stdenv, cmake, eigen, flex }:
> stdenv.mkDerivation {
>    buildInputs  = [ cmake eigen flex ];
> }
> ``
> 
> Then you can just call nix-shell to get a development environment with
> all the packages available.
> >

Ok thanks for this valuable advice
But my point here is I would like to know which gcc compiler was used for building clang
and how to eventually rebuild it.

I've crossed checked on a standard system that glog compiles without pb with clang 3.7...
The problem here is with my choices of gcc and clang... which are compatible...
or I miss something

> >
> >> --Vladimir
> >>
> >>
> >>
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