Re: Segfault Question

[Nathan Sidwell <nathan at acm dot org>]

On 12/17/18 10:11 AM, Jonathan Wakely wrote:

> The second snippet is his suggested fix for the caller of tsubst_expr
> in expand_concept. That would have been a lot more helpful as a patch:
>
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -563,7 +563,7 @@ expand_concept (tree decl, tree args)
>     ++processing_template_decl;
>     tree result = tsubst_expr (def, args, tf_none, NULL_TREE, true);
>     --processing_template_decl;
> -  if (result == error_mark_node)
> +  if (result == error_mark_node || t == NULL_TREE)
>       return error_mark_node;
>
>     /* And lastly, normalize it, check for implications, and save
>
> The point is that tsubst_expr can return NULL_TREE, we should check for it.

Are there cases that tsubst_expr returns NULL when the incoming T is 
non-null?  I.e. I'm hypothesizing DEF is NULL already.

nathan

--
Nathan Sidwell