Re: [PATCH] Partially fix PR c++/12277 (Warn on dynamic cast with known NULL results)

[Jason Merrill]

On 11/09/2015 04:30 AM, Patrick Palka wrote:

+             if (complain & tf_warning)
+               {
+                 if (VAR_P (old_expr))
+                   warning (0, "dynamic_cast of %q#D to %q#T can never 
succeed",
+                               old_expr, type);
+                 else
+                   warning (0, "dynamic_cast of %q#E to %q#T can never 
succeed",
+                               old_expr, type);
+               }
+             return build_zero_cst (type);

You also need to handle throwing bad_cast in the reference case.

Jason