Is auto* useful at compile time or is the auto keyword enough?

Question

Since the auto keyword gets the class type at compile time I was wondering if there is any efficency at all when using auto* or if there is any particular use for that expression, because auto will already get the pointer type when compiling.

Answer 1

None of this “newfangled C++11” has anything to do with efficient compilation, except in very odd corner cases. It’s all there to make it easier for humans to write and comprehend the code. auto* makes it obvious that you have a pointer-typed value, and the compiler only uses it as an additional typecheck criterion, and will issue a diagnostic if the type is not a pointer type – your code is then malformed and it’s a hard error.

I don’t recall offhand if auto* can ever participate as a disambiguator in type deduction, but if it did, that would be the technical reason to use it. Language lawyer, is there a language lawyer on board? :)

Most properly designed projects – even huge ones – should recompile quickly after changes, it’s a matter of proper partitioning of the code and having development builds that leverage such partitioning.

Answer 2

auto* makes sense in only two cases I can think of.

1) you want to make it clear to the reader that they are dealing with a pointer variable. 2) you want a compile error if what you assign to the auto* variable is not in fact a pointer.

Outside of those cases, the extra * is redundant and plain auto is just as good.

None of this has anything to do with efficiency btw. It doesn't change the final compiled code in the slightest.