[gcc r11-8568] libstdc++: Add explicit -std=gnu++17 option to test

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:2280fbfa465b2d7fe890e9a7b916ffa2eff5b934

commit r11-8568-g2280fbfa465b2d7fe890e9a7b916ffa2eff5b934
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Jun 14 13:17:40 2021 +0100

    libstdc++: Add explicit -std=gnu++17 option to test
    
    This test has no -std option so when the testsuite is run with
    -std=gnu++20 or later, this test will use that. The recent addition of
    no_unique_address will cause it to FAIL, because that's a reserved word
    after C++17. Add an explicit option, so that this test alays uses
    exactly C++17.
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/17_intro/headers/c++2017/all_attributes.cc: Add
            -std=gnu++17 option.
    
    (cherry picked from commit 45fb3d45a4d4b79a00c56fa93e9e69d9d7762ca0)

Diff:
---
 libstdc++-v3/testsuite/17_intro/headers/c++2017/all_attributes.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libstdc++-v3/testsuite/17_intro/headers/c++2017/all_attributes.cc b/libstdc++-v3/testsuite/17_intro/headers/c++2017/all_attributes.cc
index 811b3fe3613..ea2c7d20ba2 100644
--- a/libstdc++-v3/testsuite/17_intro/headers/c++2017/all_attributes.cc
+++ b/libstdc++-v3/testsuite/17_intro/headers/c++2017/all_attributes.cc
@@ -15,6 +15,7 @@
 // with this library; see the file COPYING3.  If not see
 // <http://www.gnu.org/licenses/>.
 
+// { dg-options "-std=gnu++17" }
 // { dg-do compile { target c++17 } }
 
 // Ensure the library only uses the __name__ form for attributes.