Why am I getting an error converting a Foo** --> Foo const**?, C++ FAQ

C++ FAQ

From Marshall Cline: Bjarne Stroustrup, Herb Sutter, Andrei Alexandrescu, Pearson / Addison-Wesley Publishers and I collaborated to create a new C++ Super-FAQ! It's a team effort, with huge contributions from each of us and with amazing support from dozens of brilliant editors. The result is "awesomer" than ever! I originally wrote/published the FAQ in 1991 and now look forward to this new phase - and to continue working with it for another 20 years!

On a personal note, I'm at Oculus VR and it is amazing - fabulous people doing fabulous work. We're hiring more fabulous people so write me if that's you!

FAQ: Why am I getting an error converting a `Foo` → `Foo const`? ←(in the new Super-FAQ)

It's in Section: Const correctness:

FAQ: What is "const correctness"?
FAQ: How is "const correctness" related to ordinary type safety?
FAQ: Should I try to get things const correct "sooner" or "later"?
FAQ: What does "Fred const* p" mean?
FAQ: Difference between "Fred const* p", "Fred* const p" and "Fred const* const p"?
FAQ: What does "Fred const& x" mean?
FAQ: Does "Fred& const x" make any sense?
FAQ: What does "const X& x" mean?
FAQ: What is a "const member function"?
FAQ: Using return-by-reference in a const member function?
FAQ: What's the deal with "const-overloading"?
FAQ: How a const member function can make an "invisible" change to a data member?
FAQ: Does const_cast mean lost optimization opportunities?
FAQ: Binding a pointer-to-const to a non-const object?
FAQ: Does "Fred const* p" mean that *p can't change?
FAQ: Errors trying to convert Foo** → Foo const**? (this FAQ)