libstdc++: Implement missing operator overloads in max_size_type.h

This implements operator++, operator-- and operator<=> for the
integer-class types defined in max_size_type.h, which I overlooked
when originally implementing the class.

libstdc++-v3/ChangeLog:

	* include/bits/max_size_type.h (__max_size_type::operator _Tp):
	Fix formatting.
	(__max_size_type::operator++): Define.
	(__max_size_type::operator--): Likewise.
	(__max_size_type::operator<=>): Conditionally define (in place
	of the other comparison operators).
	(__max_diff_type::operator _Tp): Fix formatting.
	(__max_diff_type::operator++): Define.
	(__max_diff_type::operator--): Likewise.
	(__max_diff_type::operator<=>): Conditionally define (in place
	of the other comparison operators).
	* testsuite/std/ranges/iota/max_size_type.cc (test01): Test
	these operator overloads.

2 files changed, 112 insertions, 2 deletions

diff --git a/libstdc++-v3/include/bits/max_size_type.h b/libstdc++-v3/include/bits/max_size_type.h
index 05984a3..27d6379 100644
--- a/libstdc++-v3/include/bits/max_size_type.h
+++ b/libstdc++-v3/include/bits/max_size_type.h
@@ -71,7 +71,8 @@ namespace ranges
       __max_size_type(const __max_diff_type& __d) noexcept;
 
       template<typename _Tp> requires integral<_Tp> || __is_int128<_Tp>
-	constexpr explicit operator _Tp() const noexcept
+	constexpr explicit
+	operator _Tp() const noexcept
 	{ return _M_val; }
 
       constexpr explicit
@@ -91,6 +92,30 @@ namespace ranges
       { return operator~() + 1; }
 
       constexpr __max_size_type&
+      operator++() noexcept
+      { return *this += 1; }
+
+      constexpr __max_size_type
+      operator++(int) noexcept
+      {
+	auto __tmp = *this;
+	++*this;
+	return __tmp;
+      }
+
+      constexpr __max_size_type&
+      operator--() noexcept
+      { return *this -= 1; }
+
+      constexpr __max_size_type
+      operator--(int) noexcept
+      {
+	auto __tmp = *this;
+	--*this;
+	return __tmp;
+      }
+
+      constexpr __max_size_type&
       operator+=(const __max_size_type& __r) noexcept
       {
 	const auto __sum = _M_val + __r._M_val;
@@ -355,6 +380,16 @@ namespace ranges
       operator==(const __max_size_type& __l, const __max_size_type& __r) noexcept
       { return __l._M_val == __r._M_val && __l._M_msb == __r._M_msb; }
 
+#if __cpp_lib_three_way_comparison
+      friend constexpr strong_ordering
+      operator<=>(const __max_size_type& __l, const __max_size_type& __r) noexcept
+      {
+	if (__l._M_msb ^ __r._M_msb)
+	  return __l._M_msb ? strong_ordering::greater : strong_ordering::less;
+	else
+	  return __l._M_val <=> __r._M_val;
+      }
+#else
       friend constexpr bool
       operator!=(const __max_size_type& __l, const __max_size_type& __r) noexcept
       { return !(__l == __r); }
@@ -379,6 +414,7 @@ namespace ranges
       friend constexpr bool
       operator>=(const __max_size_type& __l, const __max_size_type& __r) noexcept
       { return __r <= __l; }
+#endif
 
 #if __SIZEOF_INT128__
       using __rep = unsigned __int128;
@@ -417,7 +453,8 @@ namespace ranges
       { }
 
       template<typename _Tp> requires integral<_Tp> || __is_int128<_Tp>
-	constexpr explicit operator _Tp() const noexcept
+	constexpr explicit
+	operator _Tp() const noexcept
 	{ return static_cast<_Tp>(_M_rep); }
 
       constexpr explicit
@@ -437,6 +474,30 @@ namespace ranges
       { return __max_diff_type(~_M_rep); }
 
       constexpr __max_diff_type&
+      operator++() noexcept
+      { return *this += 1; }
+
+      constexpr __max_diff_type
+      operator++(int) noexcept
+      {
+	auto __tmp = *this;
+	++*this;
+	return __tmp;
+      }
+
+      constexpr __max_diff_type&
+      operator--() noexcept
+      { return *this -= 1; }
+
+      constexpr __max_diff_type
+      operator--(int) noexcept
+      {
+	auto __tmp = *this;
+	--*this;
+	return __tmp;
+      }
+
+      constexpr __max_diff_type&
       operator+=(const __max_diff_type& __r) noexcept
       {
 	_M_rep += __r._M_rep;
@@ -647,6 +708,18 @@ namespace ranges
       operator==(const __max_diff_type& __l, const __max_diff_type& __r) noexcept
       { return __l._M_rep == __r._M_rep; }
 
+#if __cpp_lib_three_way_comparison
+      constexpr strong_ordering
+      operator<=>(const __max_diff_type& __r) const noexcept
+      {
+	const auto __lsign = _M_rep._M_msb;
+	const auto __rsign = __r._M_rep._M_msb;
+	if (__lsign ^ __rsign)
+	  return __lsign ? strong_ordering::less : strong_ordering::greater;
+	else
+	  return _M_rep <=> __r._M_rep;
+      }
+#else
       friend constexpr bool
       operator!=(const __max_diff_type& __l, const __max_diff_type& __r) noexcept
       { return !(__l == __r); }
@@ -673,6 +746,7 @@ namespace ranges
       friend constexpr bool
       operator>=(const __max_diff_type& __l, const __max_diff_type& __r) noexcept
       { return !(__l < __r); }
+#endif
 
     private:
       __max_size_type _M_rep = 0;
diff --git a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
index 9284d71..983bdfb 100644
--- a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
+++ b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
@@ -145,6 +145,42 @@ test01()
   auto h = [] (auto a) { a <<= a; return a; };
   static_assert(h(max_size_t(3)) == 24);
   static_assert(h(max_diff_t(3)) == 24);
+
+  auto w = [] (auto a) {
+    const auto b = a;
+    VERIFY( a++ == b   && a == b+1 );
+    VERIFY( a-- == b+1 && a == b );
+
+    VERIFY( ++(++a) == b+2 );
+    VERIFY( --(--a) == b );
+    return true;
+  };
+  static_assert(w(max_size_t(10)));
+  static_assert(w(-max_diff_t(10)));
+
+#if __cpp_lib_three_way_comparison
+  static_assert(max_size_t{1} <=> max_size_t{9} == std::strong_ordering::less);
+  static_assert(max_size_t{3} <=> max_size_t{2} == std::strong_ordering::greater);
+  static_assert(max_size_t{5} <=> max_size_t{5} == std::strong_ordering::equal);
+  static_assert(~max_size_t{1} <=> ~max_size_t{9} == std::strong_ordering::greater);
+  static_assert(~max_size_t{3} <=> ~max_size_t{2} == std::strong_ordering::less);
+  static_assert(~max_size_t{5} <=> ~max_size_t{5} == std::strong_ordering::equal);
+  static_assert(~max_size_t{5} <=> max_size_t{9} == std::strong_ordering::greater);
+  static_assert(~max_size_t{9} <=> max_size_t{5} == std::strong_ordering::greater);
+  static_assert(max_size_t{5} <=> ~max_size_t{9} == std::strong_ordering::less);
+  static_assert(max_size_t{9} <=> ~max_size_t{5} == std::strong_ordering::less);
+
+  static_assert(max_diff_t{1} <=> max_diff_t{9} == std::strong_ordering::less);
+  static_assert(max_diff_t{3} <=> max_diff_t{2} == std::strong_ordering::greater);
+  static_assert(max_diff_t{5} <=> max_diff_t{5} == std::strong_ordering::equal);
+  static_assert(max_diff_t{-1} <=> max_diff_t{-9} == std::strong_ordering::greater);
+  static_assert(max_diff_t{-3} <=> max_diff_t{-2} == std::strong_ordering::less);
+  static_assert(max_diff_t{-5} <=> max_diff_t{-5} == std::strong_ordering::equal);
+  static_assert(max_diff_t{-5} <=> max_diff_t{9} == std::strong_ordering::less);
+  static_assert(max_diff_t{-9} <=> max_diff_t{5} == std::strong_ordering::less);
+  static_assert(max_diff_t{5} <=> max_diff_t{-9} == std::strong_ordering::greater);
+  static_assert(max_diff_t{9} <=> max_diff_t{-5} == std::strong_ordering::greater);
+#endif
 }
 
 template<bool signed_p, bool shorten_p>