[PATCH] D33919: [ADT] Make iterable SmallVector template overrides more specific

[David Blaikie via llvm-commits]

__is_input_iterator would be a private implementation detail of libc++ - it
won't be portable to use that.

What do you mean by 'InputIterator ~= iterator_traits-input_iterator_tag' ?

On Thu, Jun 8, 2017 at 10:29 AM Francis Ricci <francisjricci at gmail.com>
wrote:

> Unfortunately, it appears that InputIterator !=
> iterator_traits->input_iterator_tag, as that was one of my original
> attempts. However, it looks like std::vector's implementation uses
> std::__is_input_iterator, which appears to work so far. I'll finish
> testing and update if it works.
>
> On Thu, Jun 8, 2017 at 12:42 PM, David Blaikie <dblaikie at gmail.com> wrote:
> >
> >
> > On Wed, Jun 7, 2017 at 2:03 PM Francis Ricci <francisjricci at gmail.com>
> > wrote:
> >>
> >> I tried to stay as close as possible to the check from std::distance,
> >> which is the function that will fail to compile if you use the
> >> templated override without an iterable type. std::distance doesn't
> >> require a forward iterator, it only requires:
> >> iterator_traits<_InputIter>::difference_type, which should be defined
> >> in the same cases as iterator_traits<_InputIter>::pointer afaik.
> >
> >
> > It still seems best to not diverge from what the standard requires here..
> >
> > "This overload only participates in overload resolution if InputIt
> satisfies
> > InputIterator." (to quote the more accessible (than the stancdard)
> > http://en.cppreference.com/w/cpp/container/vector/assign as an example)
> >
> > Though maybe it's impractical/not worth the hassle, I'm not sure?
> >
> > I think it'd be a matter of using enable_if and checking the
> > iterator_category from the iterator traits, though.
> >
> >>
> >>
> >> On Wed, Jun 7, 2017 at 5:00 PM, David Blaikie <dblaikie at gmail.com>
> wrote:
> >> > Looks a bit different from the is_forward_iterator type check that
> >> > libc++
> >> > uses. Any idea what the tradeoffs are there? Why this solution is
> >> > equivalent/as good/correct?
> >> >
> >> > (should have test coverage for all 3 variants that are modified)
> >> >
> >> > On Wed, Jun 7, 2017 at 1:57 PM Francis Ricci via Phabricator
> >> > <reviews at reviews.llvm.org> wrote:
> >> >>
> >> >> fjricci updated this revision to Diff 101813.
> >> >> fjricci retitled this revision from "[ADT] Ensure that correct
> >> >> overrides
> >> >> for SmallVector assign are selected" to "[ADT] Make iterable
> >> >> SmallVector
> >> >> template overrides more specific".
> >> >> fjricci edited the summary of this revision.
> >> >> fjricci added a comment.
> >> >>
> >> >> Add unit test and migrate to iterator SFINAE checks
> >> >>
> >> >>
> >> >> https://reviews.llvm.org/D33919
> >> >>
> >> >> Files:
> >> >>   include/llvm/ADT/SmallVector.h
> >> >>   unittests/ADT/SmallVectorTest.cpp
> >> >>
> >> >>
> >> >> Index: unittests/ADT/SmallVectorTest.cpp
> >> >> ===================================================================
> >> >> --- unittests/ADT/SmallVectorTest.cpp
> >> >> +++ unittests/ADT/SmallVectorTest.cpp
> >> >> @@ -434,6 +434,15 @@
> >> >>    this->assertValuesInOrder(this->theVector, 3u, 1, 2, 3);
> >> >>  }
> >> >>
> >> >> +// Assign test
> >> >> +TYPED_TEST(SmallVectorTest, AssignNonIterTest) {
> >> >> +  SCOPED_TRACE("AssignTest");
> >> >> +
> >> >> +  this->theVector.push_back(Constructable(1));
> >> >> +  this->theVector.assign(2, 2);
> >> >> +  this->assertValuesInOrder(this->theVector, 2u, 2);
> >> >> +}
> >> >> +
> >> >>  // Move-assign test
> >> >>  TYPED_TEST(SmallVectorTest, MoveAssignTest) {
> >> >>    SCOPED_TRACE("MoveAssignTest");
> >> >> Index: include/llvm/ADT/SmallVector.h
> >> >> ===================================================================
> >> >> --- include/llvm/ADT/SmallVector.h
> >> >> +++ include/llvm/ADT/SmallVector.h
> >> >> @@ -388,7 +388,8 @@
> >> >>    void swap(SmallVectorImpl &RHS);
> >> >>
> >> >>    /// Add the specified range to the end of the SmallVector.
> >> >> -  template<typename in_iter>
> >> >> +  template <typename in_iter,
> >> >> +            typename = typename
> >> >> std::iterator_traits<in_iter>::pointer>
> >> >>    void append(in_iter in_start, in_iter in_end) {
> >> >>      size_type NumInputs = std::distance(in_start, in_end);
> >> >>      // Grow allocated space if needed.
> >> >> @@ -426,7 +427,9 @@
> >> >>      std::uninitialized_fill(this->begin(), this->end(), Elt);
> >> >>    }
> >> >>
> >> >> -  template <typename in_iter> void assign(in_iter in_start, in_iter
> >> >> in_end) {
> >> >> +  template <typename in_iter,
> >> >> +            typename = typename
> >> >> std::iterator_traits<in_iter>::pointer>
> >> >> +  void assign(in_iter in_start, in_iter in_end) {
> >> >>      clear();
> >> >>      append(in_start, in_end);
> >> >>    }
> >> >> @@ -579,7 +582,8 @@
> >> >>      return I;
> >> >>    }
> >> >>
> >> >> -  template<typename ItTy>
> >> >> +  template <typename ItTy,
> >> >> +            typename = typename std::iterator_traits<ItTy>::pointer>
> >> >>    iterator insert(iterator I, ItTy From, ItTy To) {
> >> >>      // Convert iterator to elt# to avoid invalidating iterator when
> we
> >> >> reserve()
> >> >>      size_t InsertElt = I - this->begin();
> >> >> @@ -860,7 +864,8 @@
> >> >>      this->assign(Size, Value);
> >> >>    }
> >> >>
> >> >> -  template<typename ItTy>
> >> >> +  template <typename ItTy,
> >> >> +            typename = typename std::iterator_traits<ItTy>::pointer>
> >> >>    SmallVector(ItTy S, ItTy E) : SmallVectorImpl<T>(N) {
> >> >>      this->append(S, E);
> >> >>    }
> >> >>
> >> >>
> >> >
>
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