[Bug c++/27336] "this" pointer is not assumed to be not null

[guillaume.melquiond at inria dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=27336

--- Comment #8 from Guillaume Melquiond <guillaume.melquiond at inria dot fr> 
---
It is partly fixed. In callee position, GCC now knows that "this" is non-null.
But in caller position, GCC still cannot make use of that information to remove
non-null checks from dynamic casts. The following testcase is still relevant.

struct A { void g(); };
bool f(A *a) {
  a->g();
  return a;
}