[Bug c++/81632] New: spurious -Wterminate warning about throw in destructor

["akim.demaille at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81632

            Bug ID: 81632
           Summary: spurious -Wterminate warning about throw in destructor
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: akim.demaille at gmail dot com
  Target Milestone: ---

In the following piece of code GCC issues a spurious warning about an exception
that escapes a dtor, although it is actually caught.

Observed with GCC 6 and 7.  GCC 5 does not feature -Wterminate.

$ cat /tmp/foo.cc
struct foo
{
  ~foo()
  {
    try
      {
        throw 42;
      }
    catch (int)
      {
        throw;
      }
    catch (...)
      {
      }
  }
};

int main()
{

}
$ g++-mp-6 --version
g++-mp-6 (MacPorts gcc6 6.3.0_2) 6.3.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++-mp-6 -Wterminate /tmp/foo.cc -std=c++14
/tmp/foo.cc: In destructor 'foo::~foo()':
/tmp/foo.cc:11:9: warning: throw will always call terminate() [-Wterminate]
         throw;
         ^~~~~
/tmp/foo.cc:11:9: note: in C++11 destructors default to noexcept
$ g++-mp-7 --version
g++-mp-7 (MacPorts gcc7 7-20170622_0) 7.1.
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++-mp-7 -Wterminate /tmp/foo.cc -std=c++14
/tmp/foo.cc: In destructor 'foo::~foo()':
/tmp/foo.cc:11:9: warning: throw will always call terminate() [-Wterminate]
         throw;
         ^~~~~
/tmp/foo.cc:11:9: note: in C++11 destructors default to noexcept

There is no such warning if this try/catch is wrapped in another one, so that's
really just the logic of bouncing to another catch clause that is missing.

Cheers!