[PATCH] Replace OwningPtr::isValid() with conversion to bool.

[Arthur O'Dwyer]

On Fri, Mar 7, 2014 at 8:14 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
> ================
> Comment at: include/clang/Frontend/ASTUnit.h:503
> @@ -502,3 +502,3 @@
>
> -  bool hasSema() const { return TheSema.isValid(); }
> +  bool hasSema() const { return bool(TheSema); }
>    Sema &getSema() const {
> ----------------
> I /think/ we favor C++ style casts even in this context (static_cast<bool>(TheSema)), but if not, I'd at least prefer (bool)TheSema over function-style cast (though perhaps there's not precedent there either)

Alternatively, instead of adding a terse `operator bool() const`,
Ahmed could add a `bool operator!=(std::nullptr_t) const` so that this
sort of comparison-to-null could be written as

    bool hasSema() const { return (TheSema != nullptr); }

IMHO this idiom is easier to read, and `std::unique_ptr` actually
supports both idioms so it wouldn't impede moving to `std::unique_ptr`
later.

–Arthur