Re: Coding style for C++ constructs going forward

[Christian Biesinger <cbiesinger@google.com>]

On Fri, Aug 7, 2020 at 9:06 AM Luis Machado via Gdb <gdb@sourceware.org> wrote:
>
> Hi,
>
> cc-ing the GCC mailing list, as we may want to use the same coding style
> for GDB and GCC.
>
> Yesterday I brought this topic up on IRC. I notice we started using more
> and more the "auto" keyword. In some cases, this is actually useful and
> makes the code a bit more compact. GDB has been using those more often,
> whereas GCC, for example, isn't using those too much.
>
> Looking at the coding standards for GCC
> (https://gcc.gnu.org/codingconventions.html), I don't see anything
> dictating best practices for "auto" use.
>
> I guess it is a consensus that "auto" is a good fit when dealing with
> iterators, lambda's and gnarly templates (but only when the type is
> already obvious from its use).
>
> There are other situations where "auto" may make things a little more
> cryptic when one wants to figure out the types of the variables. One
> example of this is when you have a longer function, and you use "auto"
> in a variable that lives throughout the scope of the function. This
> means you'll need to go back to its declaration and try to figure out
> what type this particular variable has.
>
> Pedro has pointed out LLVM's coding standards for "auto", which we may
> or may not want to follow/adopt:
> https://llvm.org/docs/CodingStandards.html#use-auto-type-deduction-to-make-code-more-readable
>
> It sounds like a reasonable idea to me. Thoughts?

The LLVM guide seems pretty similar to what the Google C++ guide
*used* to say, which was basically "You can use auto for iterators and
when the type is explicit on the initializer, e.g. for auto* x = new
Foo()". I liked that rule.

(The new version says "Use it if it makes the code more readable" with
no detailed guidance, which makes me sad)

Christian