[Bug sanitizer/70342] g++ -fsanitize=undefined never finishes compiling (>24h) in qtxmlpatterns test suite

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70342

--- Comment #7 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
There's some non-linearity.  This compiles in 25s, if I add another "<< A()"
then in 55s, if I add another "<< A()" then in 1m50s etc.

class A {};
class B {
public:
  B(A);
};
class C {
public:
  C operator<<(B);
};
class D {
  D(const int &);
  C m_blackList;
};
D::D(const int &) {
  m_blackList << A() << A() << A() << A() << A() << A() << A() << A() << A()
              << A() << A() << A() << A() << A() << A() << A() << A() << A()
              << A() << A() << A() << A() << A();
}