[libcxx][ranges] Add `contiguous_iterator`.

[• Quuxplusone]

libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.random.access/contiguous_iterator.compile.pass.cpp

28–32

Most importantly, please check the test iterators from test_iterators.h — e.g.

static_assert(std::contiguous_iterator<contiguous_iterator<int*>>);

Any test iterators that don't match the concepts will want to be fixed.

[zoecarver]

libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.random.access/contiguous_iterator.compile.pass.cpp

28–32

I have those a few lines above:

static_assert(!std::contiguous_iterator<input_iterator<int*> >);
static_assert(!std::contiguous_iterator<forward_iterator<int*> >);
static_assert(!std::contiguous_iterator<bidirectional_iterator<int*> >);
static_assert(!std::contiguous_iterator<random_access_iterator<int*> >);
static_assert(std::contiguous_iterator<contiguous_iterator<int*> >);

[cjdb]

Missing conformance tests:

• deque (negative test)
• vector
• span
• string
• reverse_iterator

LGTM, pending CI and added conformance tests.

[zoecarver]

• Add conformance tests.
• Fix review comments.
• Detatch from contiguous_range.

[zoecarver]

libcxx/include/__memory/pointer_traits.h

201 ↗

(On Diff #344172)

I'm going to make this into a separate PR with test.

[zoecarver]

• Grep/fix the last few conformance tests.

[zoecarver]

• Remove final remaining range test.

(Sorry for all the churn/emails!)

[zoecarver]

• Rebase on main to get the to_address fix.

[zoecarver]

• Reset changes in pointer_traits to fix the diff.

[zoecarver]

Fixing the build failures now. @Quuxplusone friendly ping :)

[zoecarver]

Fix the two failing tests.

libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp

26

Just want to confirm this is correct: vector<bool> is not a contiguous container (while normal vector is).

[cjdb]

libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp

26

Correct.

[• Quuxplusone]

LGTM % comments

libcxx/include/__iterator/concepts.h

16

At some point: Alphabetize.

libcxx/test/std/containers/sequences/vector.bool/iterator_concept_conformance.compile.pass.cpp

26

Please keep static_assert(std::random_access_iterator<reverse_iterator>); (just add the new negative asserts).

libcxx/test/std/iterators/iterator.requirements/iterator.concepts/iterator.concept.random.access/contiguous_iterator.compile.pass.cpp

15

concept contiguous_iterator;

46–50

(A) this could be operator<=>?
(B) pass-by-const-value alert! I think you wanted pass-by-const-reference.
Ditto throughout.

libcxx/test/std/iterators/predef.iterators/reverse.iterators/iterator_concept_conformance.compile.pass.cpp

42

Please keep the assert for

static_assert(std::random_access_iterator<reverse_contiguous_iterator>);

(just add the new negative assert). This also applies anywhere else in this PR that you removed a positive assert without replacing it with a stronger positive assert (if any such places exist).

[zoecarver]

Apply Arthur's comments.

[zoecarver]

Remove extra requires that's no longer needed now that to_address is SFINAE friendly.

[zoecarver]

Add back SFINAE fix.