text: //===----------------------------------------------------------------------===//
  //
  // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  // See https://llvm.org/LICENSE.txt for license information.
  // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  //
  //===----------------------------------------------------------------------===//
  
  // UNSUPPORTED: c++03, c++11, c++14, c++17
  // UNSUPPORTED: libcpp-has-no-incomplete-ranges
  
  // template<class R>
  // concept contiguous_range;
  
  #include <ranges>
  
  #include "test_range.h"
  #include "test_iterators.h"
  
  namespace ranges = std::ranges;
  
  template <template <class...> class I>
  constexpr bool check_range() {
    constexpr bool result = ranges::contiguous_range<test_range<I> >;
    static_assert(ranges::contiguous_range<test_range<I> const> == result);
    static_assert(ranges::contiguous_range<test_non_const_common_range<I> > == result);
    static_assert(ranges::contiguous_range<test_non_const_range<I> > == result);
    static_assert(ranges::contiguous_range<test_common_range<I> > == result);
    static_assert(ranges::contiguous_range<test_common_range<I> const> == result);
    static_assert(!ranges::contiguous_range<test_non_const_common_range<I> const>);
    static_assert(!ranges::contiguous_range<test_non_const_range<I> const>);
    return result;
  }
  
  static_assert(!check_range<cpp20_input_iterator>());
  static_assert(!check_range<forward_iterator>());
  static_assert(!check_range<bidirectional_iterator>());
  static_assert(!check_range<random_access_iterator>());
  static_assert(check_range<contiguous_iterator>());
  
  struct ContiguousWhenNonConst {
      const int *begin() const;
      const int *end() const;
      int *begin();
      int *end();
      int *data() const;
  };
  static_assert( std::ranges::contiguous_range<ContiguousWhenNonConst>);
  static_assert( std::ranges::random_access_range<const ContiguousWhenNonConst>);
  static_assert(!std::ranges::contiguous_range<const ContiguousWhenNonConst>);
  
  struct ContiguousWhenConst {
      const int *begin() const;
      const int *end() const;
      int *begin();
      int *end();
      const int *data() const;
  };
  static_assert( std::ranges::contiguous_range<const ContiguousWhenConst>);
  static_assert( std::ranges::random_access_range<ContiguousWhenConst>);
  static_assert(!std::ranges::contiguous_range<ContiguousWhenConst>);
  
  struct DataFunctionWrongReturnType {
      const int *begin() const;
      const int *end() const;
      const char *data() const;
  };
  static_assert( std::ranges::random_access_range<DataFunctionWrongReturnType>);
  static_assert(!std::ranges::contiguous_range<DataFunctionWrongReturnType>);
  
  struct WrongObjectness {
      const int *begin() const;
      const int *end() const;
      void *data() const;
  };
  static_assert(std::ranges::contiguous_range<WrongObjectness>);
  
  // Test ADL-proofing.
  struct Incomplete;
  template<class T> struct Holder { T t; };
  
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>*>);
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>*&>);
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>*&&>);
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>* const>);
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>* const&>);
  static_assert(!std::ranges::contiguous_range<Holder<Incomplete>* const&&>);
  
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>*[10]>);
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>*(&)[10]>);
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>*(&&)[10]>);
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>* const[10]>);
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>* const(&)[10]>);
  static_assert( std::ranges::contiguous_range<Holder<Incomplete>* const(&&)[10]>);
  