[committed] libstc++: Add dg-error for additional error in C++11 mode

[Jonathan Wakely via Gcc-patches]

When the comparison with a nullptr_t is ill-formed, there is an
additional error for C++11 mode due to the constexpr function body being
invalid.

Signed-off-by: Jonathan Wakely <jwak...@redhat.com>

libstdc++-v3/ChangeLog:

        * testsuite/20_util/tuple/comparison_operators/overloaded2.cc:
        Add dg-error for c++11_only target.

Tested powerpc64le-linux. Committed to trunk.


commit 2aaf69133f39f2409baa146e755a6c52eee4452f
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Mon Aug 2 14:41:17 2021

    libstc++: Add dg-error for additional error in C++11 mode
    
    When the comparison with a nullptr_t is ill-formed, there is an
    additional error for C++11 mode due to the constexpr function body being
    invalid.
    
    Signed-off-by: Jonathan Wakely <jwak...@redhat.com>
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/20_util/tuple/comparison_operators/overloaded2.cc:
            Add dg-error for c++11_only target.

diff --git 
a/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc 
b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc
index fc3118f85a8..a66a9315902 100644
--- a/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc
+++ b/libstdc++-v3/testsuite/20_util/tuple/comparison_operators/overloaded2.cc
@@ -50,3 +50,4 @@ auto a = std::make_tuple(nullptr, Compares{}, 2, 'U');
 auto b = a < a;
 
 // { dg-error "ordered comparison" "" { target *-*-* } 0 }
+// { dg-error "not a return-statement" "" { target c++11_only } 0 }