[gcc(refs/vendors/redhat/heads/gcc-10-branch)] c++: Add -std=gnu++20 option [PR93958]

[Jakub Jelinek]

https://gcc.gnu.org/g:e78e50d57edf4e0e49576a7a31b01477eed08223

commit e78e50d57edf4e0e49576a7a31b01477eed08223
Author: Marek Polacek <polacek@redhat.com>
Date:   Sat Feb 29 14:50:19 2020 -0500

    c++: Add -std=gnu++20 option [PR93958]
    
    One missing bit from r10-6656.  The docs and target-supports.exp
    already handle -std=gnu++20.
    
    2020-03-02  Marek Polacek  <polacek@redhat.com>
    
            PR c++/93958 - add missing -std=gnu++20.
            * c.opt: Add -std=gnu++20.

Diff:
---
 gcc/c-family/ChangeLog | 5 +++++
 gcc/c-family/c.opt     | 6 +++++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 434bac6408d..2e11b000094 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,8 @@
+2020-03-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/93958 - add missing -std=gnu++20.
+	* c.opt: Add -std=gnu++20.
+
 2020-03-01  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/92721
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index b7e4fe146b2..1cd585fa71d 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -2149,7 +2149,11 @@ Conform to the ISO 2017 C++ standard with GNU extensions.
 
 std=gnu++2a
 C++ ObjC++
-Conform to the ISO 2020(?) C++ draft standard with GNU extensions (experimental and incomplete support).
+Conform to the ISO 2020 C++ draft standard with GNU extensions (experimental and incomplete support).
+
+std=gnu++20
+C++ ObjC++ Alias(std=gnu++2a)
+Conform to the ISO 2020 C++ draft standard with GNU extensions (experimental and incomplete support).
 
 std=gnu11
 C ObjC