Tons of smaller quality improvements

[gentryx]

This PR addresses a lot of compiler warnings WRT tidbits like extraneous semicola, missing return statements or unreachable statements.

[gentryx]

CircleCI is reporting that the tests are failing because of a bad include order, but IIRC I didn't touch any includes.

/hpx/hpx/config.hpp:14:2: error: Boost.Config was included before the hpx config header. This might lead to subtile failures and compile errors. Please include <hpx/config.hpp> before any other boost header
#error Boost.Config was included before the hpx config header. This might lead to subtile failures and compile errors. Please include <hpx/config.hpp> before any other boost header

[hkaiser]

@gentryx don't worry about this, it's not your problem but was caused by a bad master branch at the point you branched off.

The changes LGTM.

[sithhell]

Is numeric_limits<std::size_t>::max() really the same as -1?

[gentryx]

@sithhell size_t is an unsigned type.

[hkaiser]

Why not write std::size_t(-1) instead?

[gentryx]

So, what are you trying to express here? Interpretation 1: num_thread should have a default value of -1. That's impossible because size_t is an unsigned type. Interpretation 2: num_thread should have the highest possible value. Then assigning -1 isn't exactly intuitive.

IIRC -1 is an integer literal. Sign propagation rules and C++' weak typing for machine word types have the consequence that the result is the same. It's a hack my compiler complains about.

[K-ballo]

So, what are you trying to express here? Interpretation 1: num_thread should have a default value of -1. That's impossible because size_t is an unsigned type. Interpretation

It's not impossible, unsigned has modulo arithmetics so each value representation V represents any and all values in the infinite set 2^N * k + V.

IIRC -1 is an integer literal

It isn't, 1 is an integer literal, -1 is a unary expression.

It's a hack my compiler complains about.

It's not a hack, it's an idiomatic way of generating the same value representation that this patch has, and without all the cruft.

That said, an explicit cast (of any kind) would be more explicitly and should silence any complains.

[gentryx]

@K-ballo WRT being idiomatic: see Thomas' first comment. Also, writing numeric_limits::max() hardly qualifies as "all the cruft".

[hkaiser]

I still think that std::size_t(-1) is conveying the intention better than numeric_limits::max(). The former is clearly defining a sentinel value, while the latter implies max() which is just confusing in this context.

[K-ballo]

std::numeric_limits lives in <limits>, every single header that uses it shall include it.

[gentryx]

@K-ballo Fixed, thanks!

[gentryx]

If the purpose of -1 is to serve as a magic number, then why not define a constant of that value with an appropriate name? Anyhow, I've changed all initializations to use explicit casts.

[hkaiser]

I'm fine with having a static std::size_t const any_thread = std::size_t(-1); and use this as the sentinel.