Note that PointerUnion::is have been soft deprecated in
PointerUnion.h:
// FIXME: Replace the uses of is(), get() and dyn_cast() with
// isa<T>, cast<T> and the llvm::dyn_cast<T>
In this patch, I'm calling call().getBase() for an instance of
PointerUnion. call() alone would return an instance of IndexCall,
which wraps PointerUnion. Note that isa<> cannot directly accept an
instance of IndexCall, at least without defining CastInfo.
I'm not touching PointerUnion::dyn_cast for now because it's a bit
complicated; we could blindly migrate it to dyn_cast_if_present, but
we should probably use dyn_cast when the operand is known to be
non-null.
43fdd6e81d