Add clang-tidy to CI with an initial set of checks

[Neverlord]

This PR adds clang-tidy to our CI pipeline with bugprone-* and clang-analyzer-* checks (plus fixes for the findings) as initial set of checks. To make the PRs easier to review, I leave it at those first two categories and enable more checks in future PRs (already working on enabling performance-* checks).

I've also added a CMake option (with configure switch) to have clang-tidy run during development (slows down the build quite a bit).

[Neverlord]

Relates #249. 🙂

[timwoj]

The previous version wasn't a reference. Was making it one intentional? Does the same need to be done in the following change?

[Neverlord]

Concerning the old code:

auto [con_res, prod_res] = make_spsc_buffer_resource<data_message>();

This deconstructs the temporary object into two values. The compiler should break this down into something like this:

auto tmp = make_spsc_buffer_resource<data_message>();
auto con_res = std::move(tmp.first);
auto prod_res = std::move(tmp.second);

For some reason, clang-tidy gets confused with object lifetimes for the code expanded from the structured binding and complains about a leak that doesn't happen. The new code simply makes the temporary variable visible and skips the moves by simply pointing back into the (now named) temporary object. The new version should expand to something like this:

auto resources = make_spsc_buffer_resource<data_message>();
auto& con_res = resources.first;
auto& prod_res = resources.second;

From a coding perspective, there is no functional change here - other than the temporary object got put on the stack and has a name now. I'd prefer the old code (simply to have a one line less of code) if it wouldn't confuse clang-tidy.

So yes, having references now is intentional to avoid extra copies. We simply need to place the result of make_spsc_buffer_resource on the stack for "un-confusing" clang-tidy regarding the object lifetimes.

[timwoj]

Same question re: references. The first two changes here make the variables references, but the third one doesn't.

[Neverlord]

Good catch, the third one is an oversight. I'll fix it.