On Fri, Jan 12, 2018 at 05:09:24PM -0500, David Malcolm wrote:
> PR c++/83814 reports an ICE introduced by the location wrapper patch
> (r256448), affecting certain memset calls within templates.
Note, I think this issue sadly affects a lot of code, so it is quite urgent.
That said, wonder if we really can't do any folding when
processing_template_decl, could we e.g. do at least maybe_constant_value,
or fold if the expression is not type nor value dependent?
BTW, never know if cp_fold_rvalue is a superset of maybe_constant_value or not.
> --- a/gcc/cp/expr.c
> +++ b/gcc/cp/expr.c
> @@ -315,3 +315,25 @@ mark_exp_read (tree exp)
> }
> }
>
> +/* Fold X for consideration by one of the warning functions when checking
> + whether an expression has a constant value. */
> +
> +tree
> +fold_for_warn (tree x)
> +{
> + /* C++ implementation. */
> +
> + /* It's not generally safe to fold inside of a template, so
> + merely strip any location wrapper and read through enum values. */
> + if (processing_template_decl)
> + {
> + STRIP_ANY_LOCATION_WRAPPER (x);
> +
> + if (TREE_CODE (x) == CONST_DECL)
> + x = DECL_INITIAL (x);
> +
> + return x;
> + }
> +
> + return c_fully_fold (x, /*for_init*/false, /*maybe_constp*/NULL);
> +}
Jakub
