Add ADL guard namespace for boost::distance(rng)

boostorg / range

Boost.org range module

http://boost.org/libs/range

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Add ADL guard namespace for boost::distance(rng) #75

Closed morinmorin closed 6 years ago

morinmorin commented 6 years ago

Move distance function template into the ADL barrier namespace and pull the name by a using-directive. This fix should be OK, since Boost.Range documentation explicitly forbids unqualified call to distance.

C++20 will have std::distance(rng) function template. This fix prevents ambiguity errors between boost::distance(rng) and std::distance(rng) caused by accidental ADL.
This fix may be necessary to fix boostorg/iterator#43.
Drive-by fix: it's OK to use boost::distance(it1, it2), but Boost.Iterator documentation advertises only boost::iterators::distance(it1, it2). So let's use it.

morinmorin commented 6 years ago

Testing on Travis CI fails, because

This PR needs to be applied in sync with boostorg/iterator#44.
But Boost.Iterator's PR was reverted, since that needs Boost.Range's PR.

Oh, cyclic dependencies of PR's...

Lastique commented 6 years ago

The change to Boost.Iterator is reapplied now.

morinmorin commented 6 years ago

The change to Boost.Iterator is reapplied now.

Thanks! I just reran the Travis testing of this PR (by force-pushing).

pdimov commented 6 years ago

I had already re-run it. It passed except for the last job, which fails because libc++ wants random engines to have constexpr min/max, and the one in random_shuffle.cpp appears not to.

pdimov commented 6 years ago

OK, I'm going to merge this and see how it goes.

pdimov commented 6 years ago

Would be nice if we could fix the (unrelated) Travis failure though.

morinmorin commented 6 years ago

Thanks for merging.

Would be nice if we could fix the (unrelated) Travis failure though.

Definitely! (though I don't have any insight into how to fix that...)