From 0ca730591a6ddfdb55a2511884ded65ab44aa5d8 Mon Sep 17 00:00:00 2001
From: Casey Carter <Casey@Carter.net>
Date: Sat, 10 Feb 2018 16:03:49 -0800
Subject: [PATCH] Implement iterator_category per TS

Drive-by: remove unused is_lvalue_reference_v
---
 include/stl2/detail/iterator/concepts.hpp | 16 +++++++++-------
 include/stl2/detail/range/access.hpp      | 16 +++++-----------
 include/stl2/type_traits.hpp              |  3 ---
 test/concepts/iterator.cpp                |  2 ++
 4 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/include/stl2/detail/iterator/concepts.hpp b/include/stl2/detail/iterator/concepts.hpp
index 43f420d91..7285fa0d4 100644
--- a/include/stl2/detail/iterator/concepts.hpp
+++ b/include/stl2/detail/iterator/concepts.hpp
@@ -458,10 +458,13 @@ STL2_OPEN_NAMESPACE {
 
 	template <class> struct iterator_category {};
 
-	template <_IsNot<is_void> T>
-	struct iterator_category<T*> {
-		using type = ext::contiguous_iterator_tag;
-	};
+	template <class T>
+	struct iterator_category<T*>
+	: std::enable_if<std::is_object<T>::value, ext::contiguous_iterator_tag> {};
+
+	template <class T>
+	struct iterator_category<const T>
+	: iterator_category<T> {};
 
 	template <detail::MemberIteratorCategory T>
 	struct iterator_category<T> {
@@ -481,8 +484,7 @@ STL2_OPEN_NAMESPACE {
 	struct iterator_category<T> {};
 
 	template <class T>
-	using iterator_category_t =
-		meta::_t<iterator_category<remove_cv_t<T>>>;
+	using iterator_category_t = meta::_t<iterator_category<T>>;
 
 	///////////////////////////////////////////////////////////////////////////
 	// Iterator [iterators.iterator]
@@ -681,7 +683,7 @@ STL2_OPEN_NAMESPACE {
 		concept bool ContiguousIterator =
 			RandomAccessIterator<I> &&
 			DerivedFrom<iterator_category_t<I>, contiguous_iterator_tag> &&
-			_Is<reference_t<I>, is_lvalue_reference> &&
+			std::is_lvalue_reference<reference_t<I>>::value &&
 			Same<value_type_t<I>, __uncvref<reference_t<I>>>;
 	}
 
diff --git a/include/stl2/detail/range/access.hpp b/include/stl2/detail/range/access.hpp
index 685c66ef3..1194b22b6 100644
--- a/include/stl2/detail/range/access.hpp
+++ b/include/stl2/detail/range/access.hpp
@@ -501,8 +501,7 @@ STL2_OPEN_NAMESPACE {
 		struct fn {
 			// Prefer member
 			template <class R>
-			requires
-				has_member<R>
+			requires has_member<R>
 			constexpr auto operator()(R& r) const
 			STL2_NOEXCEPT_RETURN(
 				r.data()
@@ -510,8 +509,7 @@ STL2_OPEN_NAMESPACE {
 
 			// Return begin(r) if it's a pointer
 			template <class R>
-			requires
-				!has_member<R> && has_pointer_iterator<R>
+			requires !has_member<R> && has_pointer_iterator<R>
 			constexpr auto operator()(R& r) const
 			STL2_NOEXCEPT_RETURN(
 				__stl2::begin(r)
@@ -520,9 +518,7 @@ STL2_OPEN_NAMESPACE {
 			// Extension: Support contiguous ranges with non-pointer
 			//            iterators.
 			template <class R>
-			requires
-				!has_member<R> &&
-				!has_pointer_iterator<R> &&
+			requires !has_member<R> && !has_pointer_iterator<R> &&
 				has_contiguous_iterator<R>
 			constexpr auto operator()(R& r) const
 			noexcept(noexcept(__stl2::begin(r) == __stl2::end(r)
@@ -542,10 +538,8 @@ STL2_OPEN_NAMESPACE {
 
 			template <class R>
 			[[deprecated]] constexpr auto operator()(const R&& r) const
-			noexcept(noexcept(declval<const fn&>()(r)))
-			requires
-				has_member<const R> ||
-				has_pointer_iterator<const R> ||
+			noexcept(noexcept(std::declval<const fn&>()(r)))
+			requires has_member<const R> || has_pointer_iterator<const R> ||
 				has_contiguous_iterator<const R>
 			{
 				return (*this)(r);
diff --git a/include/stl2/type_traits.hpp b/include/stl2/type_traits.hpp
index 76018342f..f5ce8aeb5 100644
--- a/include/stl2/type_traits.hpp
+++ b/include/stl2/type_traits.hpp
@@ -223,9 +223,6 @@ STL2_OPEN_NAMESPACE {
 		__stl2::Common{T, U}
 		constexpr bool Common<T, U> = true;
 	}
-
-	template <typename T>
-	constexpr auto is_lvalue_reference_v = is_lvalue_reference<T>::value;
 } STL2_CLOSE_NAMESPACE
 
 #endif
diff --git a/test/concepts/iterator.cpp b/test/concepts/iterator.cpp
index 9654f2652..92e78e4c9 100644
--- a/test/concepts/iterator.cpp
+++ b/test/concepts/iterator.cpp
@@ -158,6 +158,8 @@ namespace associated_type_test {
 	template <class T, bool B, class U>
 	using test = std::is_same<ns::iterator_category_t<iterator<T, B>>, U>;
 
+	CONCEPT_ASSERT(!meta::is_trait<ns::iterator_category<void*>>());
+	CONCEPT_ASSERT(!meta::is_trait<ns::iterator_category<int(*)()>>());
 	CONCEPT_ASSERT(!meta::is_trait<ns::iterator_category<iterator<std::output_iterator_tag, false>>>());
 	CONCEPT_ASSERT(!meta::is_trait<ns::iterator_category<iterator<std::output_iterator_tag, true>>>());