require et random_device for cons token test

[Alexandre Oliva]

On Mar 24, 2021, Jonathan Wakely <jwakely@redhat.com> wrote:

> diff --git a/libstdc++-v3/testsuite/util/testsuite_random.h b/libstdc++-v3/testsuite/util/testsuite_random.h
> index 0b670bfb771..c8323078492 100644
> --- a/libstdc++-v3/testsuite/util/testsuite_random.h
> +++ b/libstdc++-v3/testsuite/util/testsuite_random.h
> @@ -197,6 +197,19 @@ namespace __gnu_test
>    }
>  #endif
 
> +  // Check whether TOKEN can construct a std::random_device successfully.
> +  inline bool
> +  random_device_available(const std::string& token) noexcept
> +  {
> +    try {
> +      std::random_device dev(token);
> +      return true;
> +    } catch (...) {
> +      std::printf("random_device(\"%s\") not available\n", token);

Another nit: I'm seeing line noise (do people still use this term? :-)
in libstdc++.log where unavailable random_device tokens should appear.
I suspect the token has to be converted to a C string in the call above.

-- 
Alexandre Oliva, happy hacker  https://FSFLA.org/blogs/lxo/
   Free Software Activist         GNU Toolchain Engineer
        Vim, Vi, Voltei pro Emacs -- GNUlius Caesar