Implement C++20 constexpr comparison operators for __debug::array (P1023).

	* include/debug/array: Add C++20 constexpr to comparison operators.
	* testsuite/23_containers/array/tuple_interface/get_debug_neg.cc: Adapt
	dg-error line numbers.
	* testsuite/23_containers/array/tuple_interface/
	tuple_element_debug_neg.cc: Likewise.

From-SVN: r276375

libstdc++-v3/include/debug/array

@@ -234,16 +234,19 @@ namespace __debug
 
   // Array comparisons.
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return std::equal(__one.begin(), __one.end(), __two.begin()); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator!=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one == __two); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
     {
@@ -252,16 +255,19 @@ namespace __debug
     }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator>(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return __two < __one; }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator<=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one > __two); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator>=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one < __two); }

libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_debug_neg.cc

@@ -27,6 +27,6 @@ int n1 = std::get<1>(a);
 int n2 = std::get<1>(std::move(a));
 int n3 = std::get<1>(ca);
 
-// { dg-error "static assertion failed" "" { target *-*-* } 288 }
-// { dg-error "static assertion failed" "" { target *-*-* } 297 }
-// { dg-error "static assertion failed" "" { target *-*-* } 305 }
+// { dg-error "static assertion failed" "" { target *-*-* } 294 }
+// { dg-error "static assertion failed" "" { target *-*-* } 303 }
+// { dg-error "static assertion failed" "" { target *-*-* } 311 }

libstdc++-v3/testsuite/23_containers/array/tuple_interface/tuple_element_debug_neg.cc

@@ -22,4 +22,4 @@
 
 typedef std::tuple_element<1, std::array<int, 1>>::type type;
 
-// { dg-error "static assertion failed" "" { target *-*-* } 331 }
+// { dg-error "static assertion failed" "" { target *-*-* } 376 }