[Buildroot] [Patch v4 3/3] rust: new package

[Arnout Vandecappelle]

On 10-04-17 21:02, Jörg Krause wrote:
> Hi,
> 
> On Sat, 2017-04-08 at 12:09 +0200, Eric Le Bihan wrote:
[snip]
>> Currently Buildroot only offers downloading binary versions of the C/C++
>> cross-compilers. It does not take into account alternative C/C++
>> cross-compilers like LLVM/Clang or compilers for new languages like
>> Rust, D, or Haskell (though I do not know if Haskell is useful on
>> embedded systems).

 There's a huge difference between alternative C/C++ compilers and compilers for
other languages.

 Compilers for other languages we already have: python, mono, erlang. These are
just normal packages, and any package in that language depends on the host-xxx
package to provide the compiler. Similar to how packages that use the cmake
buildsystem depend on the host-cmake package.

 Alternative C/C++ compilers are something else entirely, because they replace
the special 'toolchain' target.

 Only when you can build an entire system with only the Rust compiler and
without C/C++ compiler you can consider them equivalent. That day is still far away.

> For now, we could use the host rustc package to fetch the latest stable
> binary for the host architecture. Additionally, we could add the option
> to build the Rust compiler within Buildroot. In my opinion, this option
> only makes sense if the compiler can be configured meaningfully.

 I agree.


>> So, would it help to have a "Programming Languages" section in
>> menuconfig where you can select Rust (or any other language) and choose
>> between a using a pre-built compiler or build it from source?
> 
> In my opinion it would make more sense to have a menu "Toolchains" with
> the submenus "C/C++ Toolchain", "Rust Toolchain", ...

 Given what I wrote above, I disagree. For the time being it's fine in the host
packages menu. If that menu becomes too large, we could add something like an
'Alternative programming languages' menu.



>> And where shoud LLVM/clang be exposed?
> 
> I would put it into "C/C++ Toolchain" (if we had such a menu).

 That's slightly more complicated. LLVM is just a library so it's just in the
host menu. clang is a compiler that can be a replacement for gcc, so it'd have
to go into the toolchain menu.

 Actually, Romain is working on LLVM/Clang. He's going to start adding it as a
normal host package, so not as a replacement of gcc as the toolchain.

 Regards,
 Arnout

> 
>> Note: Building a cross-compiler for D can be done via a patch to GCC
>> thanks to GDC [1], but IIRC cross-compiling libphobos, the standard
>> library, is another matter.
>>
>> [1] https://github.com/D-Programming-GDC/GDC/releases
> 
> Jörg
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-- 
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
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