[RFC / Patch] C++/26099 or front-end support to type traits

Mike Stump mrs@apple.com
Tue Mar 13 16:42:00 GMT 2007


On Mar 13, 2007, at 8:44 AM, Paolo Carlini wrote:
> --- cp/cp-tree.def	(revision 122814)
> +++ cp/cp-tree.def	(working copy)
> @@ -422,6 +422,12 @@
>     index is a machine integer.  */
>  DEFTREECODE (ARGUMENT_PACK_SELECT, "argument_pack_select",  
> tcc_exceptional, 0)
>
> +/** C++ extensions. */
> +
> +/* Represents a trait expression during template expansion. Operand 0
> +   is the kind of trait.  Operand 1 the queried type.  */
> +DEFTREECODE (TRAIT_EXPR, "trait_expr", tcc_expression, 2)

I object to any more new tree codes, without us first setting a  
direction we want to go.  I have a patch to Objective-C/C++ to reduce  
the tree codes we use, so that we can fit back into 256.  If we  
decide to go smaller and stay that way, there are ways to maintain no  
new tree codes, but, we're going to have to take a hard line on them,  
as we are totally out now.

For speed and size, we may well want to stay inside the 256 limit.

Let set a direction to go first, before we make it impossible to stay  
inside the 256 limit.



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