Re: [PATCH] gdbsupport: add support for references to checked_static_cast

[Lancelot SIX <lsix@lancelotsix.com>]

Hi Simon,

> diff --git a/gdbsupport/gdb-checked-static-cast.h b/gdbsupport/gdb-checked-static-cast.h
> index bc75244bddd0..7e5a69a6474d 100644
> --- a/gdbsupport/gdb-checked-static-cast.h
> +++ b/gdbsupport/gdb-checked-static-cast.h
> @@ -66,6 +66,22 @@ checked_static_cast (V *v)
>    return result;
>  }
>  
> +/* Same as the above, but to cast from a reference type to another.  */
> +
> +template<typename T, typename V>
> +T
> +checked_static_cast (V &v)
> +{
> +  static_assert (std::is_reference<T>::value, "target must be a reference type");

Have you considered incorporating this constraint inside
checked_static_cast's signature?  It could look like something like
this:

    template<typename T, typename V>
    typename std::enable_if<std::is_reference<T>::value, T>::type
    checked_static_cast (V &v)
    {
      ...
    }

If T is not a reference, then this template won't be instantiated at all
instead of instantiating it and having an error.  This could allow other
templates / functions to be considered if they matched instead of just
producing an error.

I do agree that this can end-up a bit more difficult to read for someone
not used to read this kind of code.

Best,
Lancelot.

> +
> +  using T_no_R = typename std::remove_reference<T>::type;
> +  using T_P = typename std::add_pointer<T_no_R>::type;
> +
> +  using V_no_R = typename std::remove_reference<V>::type;
> +
> +  return *checked_static_cast<T_P, V_no_R> (&v);
> +}
> +
>  }
>  
>  #endif /* COMMON_GDB_CHECKED_DYNAMIC_CAST_H */
> 
> base-commit: c96452ad168cf42ad42f0d57214dddb38d5fae88
> -- 
> 2.40.1
>