We warn about undefined calls to pure virtual functions from constructors and destructors:

struct Base {
    virtual void f() = 0;
    Base() { f(); }
};

<source>: In constructor 'Base::Base()':
<source>:3:15: warning: pure virtual 'virtual void Base::f()' called from constructor
    3 |     Base() { f(); }
      |              ~^~


But for indirect calls we don't warn:

struct Base {
    virtual void f() = 0;
    Base() { g(); }
    void g() { f(); }
};

It would be good if IPA could warn for this case too. After g() is inlined into the constructor we know that the call to f() is undefined.

I assume this would mean moving the warning from the front end to the middle end.