Work around llvm/llvm-project#143918 and llvm/llvm-project#154813

Author: davidstone

source/containers/adapt_iterator.cpp

@@ -142,7 +142,8 @@ struct adapt_iterator :
 		return it.m_traits.get().dereference(it.base());
 	}
 
-	friend constexpr auto operator+(adapt_iterator lhs, adapted_addable<Iterator, Traits> auto const rhs) -> adapt_iterator {
+	// `same_as` works around https://github.com/llvm/llvm-project/issues/143918
+	friend constexpr auto operator+(std::same_as<adapt_iterator> auto lhs, adapted_addable<Iterator, Traits> auto const rhs) -> adapt_iterator {
 		auto base = lhs.m_traits.get().add(std::move(lhs).base(), rhs);
 		return adapt_iterator(std::move(base), std::move(lhs).m_traits);
 	}

source/containers/algorithms/reverse_iterator.cpp

@@ -51,18 +51,22 @@ struct reverse_traits {
 		return *::containers::prev(it);
 	}
 
+	// All of these `OPERATORS_RETURNS` are needed to work around
+	// https://github.com/llvm/llvm-project/issues/154813
+
 	static constexpr auto add(random_access_iterator auto it, auto const offset) OPERATORS_RETURNS(
 		it - offset
 	)
 
-	static constexpr auto subtract(random_access_iterator auto const lhs, random_access_iterator auto const rhs) {
-		return rhs - lhs;
-	}
+	static constexpr auto subtract(random_access_iterator auto const lhs, random_access_iterator auto const rhs) OPERATORS_RETURNS(
+		rhs - lhs
+	)
 
-	static constexpr auto compare(random_access_iterator auto const lhs, random_access_iterator auto const rhs) {
-		return rhs <=> lhs;
-	}
-	static constexpr auto equal(iterator auto const lhs, iterator auto const rhs) {
+	static constexpr auto compare(random_access_iterator auto const lhs, random_access_iterator auto const rhs) OPERATORS_RETURNS(
+		rhs <=> lhs
+	)
+	template<iterator LHS, iterator RHS> requires bounded::equality_comparable<LHS, RHS>
+	static constexpr auto equal(LHS const lhs, RHS const rhs) -> bool {
 		return rhs == lhs;
 	}
 };

source/containers/iterator_to_sentinel.cpp

@@ -3,31 +3,35 @@
 // (See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt)
 
+module;
+
+#include <operators/returns.hpp>
+
 export module containers.iterator_to_sentinel;
 
-import bounded;
 import std_module;
 
 namespace containers {
 
 export template<typename Iterator>
 struct iterator_to_sentinel {
+private:
+	[[no_unique_address]] Iterator m_base;
+public:
 	iterator_to_sentinel() = default;
 
 	constexpr explicit iterator_to_sentinel(Iterator iterator):
 		m_base(std::move(iterator))
 	{
 	}
 
+	friend constexpr auto operator==(iterator_to_sentinel const &, iterator_to_sentinel const &) -> bool = default;
 	friend constexpr auto operator==(
-		bounded::equality_comparable<Iterator> auto const & lhs,
-		iterator_to_sentinel const & rhs
-	) -> bool {
-		return lhs == rhs.m_base;
-	}
-
-private:
-	[[no_unique_address]] Iterator m_base;
+		iterator_to_sentinel const & lhs,
+		auto const & rhs
+	) OPERATORS_RETURNS(
+		lhs.m_base == rhs
+	)
 };
 
 } // namespace containers