That's true. And I see the other example answers they have written do assume the pointer can be null, although the original class makes no indication of this.
To make the question clearer they should have added a function on the original class that checks (or doesn't check) the pointer before dereferencing it, thereby clarifying whether query being null is valid or not.
Move assignment has nothing to do with 'clearing fields' or whatever it's that the moved-to value steals what it can and leaves the moved from value in a valid but unspecified state. Notably, you should still be able to
assign-to and destroy a moved-from value.
It's an invariant of the 'DirectorySearchResult' class that query is non-null, as the destructor deletes it without checking it for nullity. The most straight-forward and efficient way to achieve both the stealing and the valid state is to swap the pointers.
Exposing Web APIs (e.g. DOM) to WASM and projecting them into native languages seems like it overlaps a lot with defining actual native API projections that would be shared between browser implementations.
It doesn't read like this is an explicit goal of the project, but are we going to get this by accident? Being able to use the same X code (where X is your favourite statically-compilable language) to generate both a WASM version that runs on the web and a statically-compiled version that links to the Y browser source (where Y can be whichever browser works for you because they all support the same native API) would be awesome.
Cheeky question: have you Googlers thought about revising this guideline? It seemed weird to me when I read it years ago and it seems to be getting more and more unconventional. When I see a pointer argument in most C++ code now I would assume that passing a null ptr is not an error, but I see quite a lot of the code in this library doesn't check for null pointers inside the function body and would explode if you passed one in.
This doesn't mean I don't sympathize with the justification in the style guide: "References can be confusing, as they have value syntax but pointer semantics". If C++ had a non-null, non-reassignable pointer it might do a lot of what references do and be clearer, particularly for generic code. I don't really know, but references are what we have, they suit indicating the expectation of non-nullity, and it seems to me that the benefit of clearly communicating that expectation gets you more of a benefit than the confusion around semantics takes away.
To make the question clearer they should have added a function on the original class that checks (or doesn't check) the pointer before dereferencing it, thereby clarifying whether query being null is valid or not.