GCC has gotten better indeed, but it's still in a different league than Clang. I still get into situations where I can't make heads-or-tails of what GCC is saying to me, which can usually be easily solved by switching to Clang.
One problem here is that GCC emits certain warnings as part of the optimizer, which results in many false positives that are essentially impossible for the lay programmer to understand. For example, jump threading might duplicate some code path and propagate constants in it, and then warn about an uninitialized variable / out of range access / etc in that code-path, even though it does not exist in that form in the original program.
I don't do C++ anymore but I will forever remember the Vtable hell "messages" when doing OOP and doing a slight unintuitive mistake about destructor or constructor.
Is this still a thing in clang?