[committed] libstdc++: Clarify static_assert message

[Jonathan Wakely via Gcc-patches]

libstdc++-v3/ChangeLog:

        * include/bits/move.h (forward): Change static_assert message
        to be unambiguous about what must be true.
        * testsuite/20_util/forward/c_neg.cc: Adjust dg-error.
        * testsuite/20_util/forward/f_neg.cc: Likewise.

Tested powerpc64le-linux. Committed to trunk.


commit 41019bfae2673a818a9b7d08742f3ef91c0deade
Author: Jonathan Wakely <jwak...@redhat.com>
Date:   Tue Apr 6 16:34:48 2021

    libstdc++: Clarify static_assert message
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/move.h (forward): Change static_assert message
            to be unambiguous about what must be true.
            * testsuite/20_util/forward/c_neg.cc: Adjust dg-error.
            * testsuite/20_util/forward/f_neg.cc: Likewise.

diff --git a/libstdc++-v3/include/bits/move.h b/libstdc++-v3/include/bits/move.h
index d36e4b28f37..feacae084c9 100644
--- a/libstdc++-v3/include/bits/move.h
+++ b/libstdc++-v3/include/bits/move.h
@@ -87,7 +87,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     forward(typename std::remove_reference<_Tp>::type&& __t) noexcept
     {
       static_assert(!std::is_lvalue_reference<_Tp>::value, "template argument"
-                   " substituting _Tp is an lvalue reference type");
+                   " substituting _Tp must not be an lvalue reference type");
       return static_cast<_Tp&&>(__t);
     }
 
diff --git a/libstdc++-v3/testsuite/20_util/forward/c_neg.cc 
b/libstdc++-v3/testsuite/20_util/forward/c_neg.cc
index 884100da42e..dc7ec51bde6 100644
--- a/libstdc++-v3/testsuite/20_util/forward/c_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/forward/c_neg.cc
@@ -17,7 +17,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// { dg-error "static assertion failed" "" { target *-*-* } 89 }
+// { dg-error "must not be an lvalue reference" "" { target *-*-* } 0 }
 
 #include <list>
 
diff --git a/libstdc++-v3/testsuite/20_util/forward/f_neg.cc 
b/libstdc++-v3/testsuite/20_util/forward/f_neg.cc
index 90d3152ffcd..4ccd7264c65 100644
--- a/libstdc++-v3/testsuite/20_util/forward/f_neg.cc
+++ b/libstdc++-v3/testsuite/20_util/forward/f_neg.cc
@@ -17,7 +17,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
-// { dg-error "static assertion failed" "" { target *-*-* } 89 }
+// { dg-error "must not be an lvalue reference" "" { target *-*-* } 0 }
 
 #include <utility>