[cfe-dev] static analyzer bug && diagnostics about suspicious casts

[Pavel Labath]

Greetings,

recently I've found a bug in the static analyzer <
http://llvm.org/bugs/show_bug.cgi?id=16308>, where it crashed processing
code like this:
-----

struct A;
struct B{ virtual ~B(); };
class B2 : public B { };
void f(A *a) {
  B *b=(B *)a;
  B2 *b2=dynamic_cast<B2 *>(b);
}

-----

because A has incomplete type. Besides fixing the crash, I was
thinking I could add a diagnostic which would detect patterns like
this. The problem here is the reinterpret_cast to a
non-standard-layout type, which invokes undefined behavior. Since this
is fairly easy to detect, I started wondering if there is a reason it
is not implemented yet. Is it because the pattern is too common in the
code and would be an annoyance? Or am I missing something obvious here
?


cheers,

pl
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