Re: [Boost-build] adding tests conditional on compiler's C++11 support

Subject: Re: [Boost-build] adding tests conditional on compiler's C++11 support
From: John Maddock (jz.maddock_at_[hidden])
Date: 2016-11-13 14:37:12

On 12/11/2016 19:44, Robert Ramey wrote:
> I spent a little time investigating this issue and a couple of things 
> have occurred to me.
>
> I still after all these years can't get the hang of boost build syntax 
> - but I still tried to look through how these "requires" statements 
> are implemented.  I found the files in config/test. Here's one
>
> #include <forward_list>
>
> namespace boost_no_cxx11_hdr_forward_list {
>
> int test()
> {
>   std::forward_list<int> l(2u, 2);
>   return *l.begin() == 2 ? 0 : 1;
> }
>
> }
>
> Now it seems to me that this really should be:
>
> #include <config.hpp>
> #include <forward_list>
>

No.  The tests are used to test Boost.Config, the one thing they must 
never ever do is include config.hpp.

If I have some spare time (and I'm sorry, but I simply don't at 
present), I'll install gcc-4.2 and see what the issue is.

> The test matrix shows a lot of places where test_forward_list is being 
> run (and passing FWIW) on compilers which look like they are invoked 
> in such a way that they don't support C++11+.  This is very, very 
> confusing and makes it unclear just what the test system results 
> actually mean and how they are meant to be used.

If in doubt about what a compiler is, look at the config_info output for 
that test runner, for example: 
http://www.boost.org/development/tests/develop/developer/output/Sandia-darwin-c++11-boost-bin-v2-libs-config-test-config_info-test-darwin-4-2-1-debug.html 
Note that the name of the test-runner in this case is 
"Sandia-darwin-c++11" which sort of gives things away, even if the 
column heading simply says "gcc-4.2.1".

>
> Another issue:
>
> The mngw tests are all failing to compile.  (though it seems that the 
> libraries are being built.) This seems to be because that the file 
> system library library needs BOOST_NO_STD_WSTRING in order to build. 
> So in this case, it would likely be better just to not run the tests 
> for the wide character versions of archives at all.  For the Nth time, 
> I read over the boost build syntax and I can't figure out how to 
> implement this.  I'm happy to read any suggestions.  Another idea 
> would be to remove dependency of the serialization library tests on 
> the boost filesystem library.  I used to be this way, but someone 
> "helpfully" improved the test code so that it now depends upon this 
> library. I left this in as it did seem to be an improvement.  So a 
> bjam solution would likely be better.  I'm all ears.
>
> Of course it's not all that clear why boost.filesystem should depend 
> upon wstring when it could conjure up basic_string<wchar_t> but I 
> can't go everywhere.

They're the same thing!

Best, John.