[cfe-commits] PATCH [1/2]: Implementation of Embarcadero expression traits

[Douglas Gregor]

On Feb 19, 2011, at 12:41 AM, Abramo Bagnara wrote:

> Il 18/02/2011 23:53, John Wiegley ha scritto:
>> Patch authored by David Abrahams.
>> 
>> These two expression traits (__is_lvalue_expr, __is_rvalue_expr) are used for
>> parsing code that employs certain features of the Embarcadero C++ compiler.
> 
> I don't see the point for introducing another AST node
> (ExpressionTraitExpr): __is_lvalue_expr/__is_rvalue_expr are
> conceptually equivalent to e.g. __builtin_constant_p.
> 
> I think they should be implemented in the same way.
> 
> I'm missing something?

I'd really rather avoid using a __builtin-like mechanism for this, because that implies that we're actually calling a function with a signature like

  bool __is_lvalue_expr(…);

However, we really don't want the ellipsis conversion to occur on the argument, nor do we want to accept multiple arguments, or add hacks to Sema to work around the limitations of the built-in handling mechanism.

	- Doug