[Clang] Properly deprecate __reference_binds_to_temporary (#141909)

At the time `__reference_constructs_from_temporary` got implemented,
`__reference_binds_to_temporary` was mentioned as deprecated in
`LanguageExtensions.rst`, but no deprecation warning was emitted. This
PR adds the previously missing warning.

Author: frederick-vs-ja

clang/docs/ReleaseNotes.rst

@@ -310,6 +310,8 @@ Non-comprehensive list of changes in this release
   different than before.
 - Fixed a crash when a VLA with an invalid size expression was used within a
   ``sizeof`` or ``typeof`` expression. (#GH138444)
+- Deprecation warning is emitted for the deprecated ``__reference_binds_to_temporary`` intrinsic.
+  ``__reference_constructs_from_temporary`` should be used instead. (#GH44056)
 
 New Compiler Flags
 ------------------

clang/lib/Sema/SemaTypeTraits.cpp

@@ -1458,6 +1458,9 @@ void DiagnoseBuiltinDeprecation(Sema &S, TypeTrait Kind, SourceLocation KWLoc) {
   case UTT_IsTriviallyRelocatable:
     Replacement = clang::UTT_IsCppTriviallyRelocatable;
     break;
+  case BTT_ReferenceBindsToTemporary:
+    Replacement = clang::BTT_ReferenceConstructsFromTemporary;
+    break;
   default:
     return;
   }

clang/test/SemaCXX/deprecated-builtins.cpp

@@ -15,6 +15,7 @@ void f() {
     a = __has_trivial_constructor(A);  // expected-warning-re {{__has_trivial_constructor {{.*}} use __is_trivially_constructible}}
     a = __has_trivial_move_constructor(A);  // expected-warning-re {{__has_trivial_move_constructor {{.*}} use __is_trivially_constructible}}
     a = __has_trivial_destructor(A);  // expected-warning-re {{__has_trivial_destructor {{.*}} use __is_trivially_destructible}}
+    a = __reference_binds_to_temporary(const A&, A); // expected-warning-re {{__reference_binds_to_temporary {{.*}} use __reference_constructs_from_temporary}}
 
 }