[Concepts] Deprecate -fconcepts-ts, enable Concepts under -std=c++2a

Now with concepts support merged and mostly complete, we do not need -fconcepts-ts
(which was also misleading as we were not implementing the TS) and can enable
concepts features under C++2a. A warning will be generated if users still attempt
to use -fconcepts-ts.

(cherry picked from commit 67c608a9695496cfc9d3fdf9d0b12b554ac6b4df)

1 files changed, 2 insertions, 3 deletions

diff --git a/clang/test/CXX/class/class.compare/class.spaceship/p2.cpp b/clang/test/CXX/class/class.compare/class.spaceship/p2.cpp
index 1290a063e79..a912384ccf7 100644
--- a/clang/test/CXX/class/class.compare/class.spaceship/p2.cpp
+++ b/clang/test/CXX/class/class.compare/class.spaceship/p2.cpp
@@ -118,8 +118,7 @@ namespace BadDeducedType {
 
   template<typename T> concept CmpCat = true;
   struct D {
-    // FIXME: Once we support P1141R2, we should give a better diagnostic here:
-    // {{deduced return type for defaulted three-way comparison operator must be 'auto', not 'CmpCat auto'}}
-    friend CmpCat auto operator<=>(const D&, const D&) = default; // expected-error {{unknown type name 'CmpCat'}}
+    // expected-error@+1 {{deduced return type for defaulted three-way comparison operator must be 'auto', not 'CmpCat auto'}}
+    friend CmpCat auto operator<=>(const D&, const D&) = default;
   };
 }