https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95984
Martin Sebor <msebor at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Last reconfirmed| |2020-06-29
CC| |jason at gcc dot gnu.org,
| |mpolacek at gcc dot gnu.org
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
If I'm reading the dump right the front end constructs a lambda object and
calls its member operator() with a null this pointer:
;; Function static decltype (((const callback<main()::<lambda(int)>
>::<lambda(auto:1 ...)>*)0)->operator()<auto:1
...>(static_cast<auto:1&&>(callback::._anon_2::_FUN::<unnamed>) ...))
callback<main()::<lambda(int)> >::<lambda(auto:1 ...)>::_FUN(auto:1 ...) [with
auto:1 = {int}; decltype (((const callback<main()::<lambda(int)>
>::<lambda(auto:1 ...)>*)0)->operator()<auto:1
...>(static_cast<auto:1&&>(callback::._anon_2::_FUN::<unnamed>) ...)) = void]
(null)
;; enabled by -tree-original
<<cleanup_point <<< Unknown tree: expr_stmt
callback<main()::<lambda(int)> >::<lambda(auto:1 ...)>::operator()<int> (0B,
D.2439) >>>>>;
return;
So it seems like the warning code is doing what it's supposed to.
The ICE is triggered by the C++ front end printing the instantiation context
(print_instantiation_full_context), the pretty printer formatting the template
specialization, calling into the C++ front end to perform type substitution,
and the FE ending up calling check_nonnull_arg() on the call, which ends up
triggering the warning and re-entering the diagnostic machinery. There is
nothing out of the ordinary the warning does to do this so it must be a latent
problem in the C++ front end that the warning exposed. I expect Jason or Marek
have seen and deal with something like this before.
