Add getSwift57Availability() with a future platform version

Author: aschwaighofer

include/swift/AST/ASTContext.h

@@ -886,6 +886,10 @@ class ASTContext final {
   /// compiler for the target platform.
   AvailabilityContext getSwift56Availability();
 
+  /// Get the runtime availability of features introduced in the Swift 5.7
+  /// compiler for the target platform.
+  AvailabilityContext getSwift57Availability();
+
   // Note: Update this function if you add a new getSwiftXYAvailability above.
   /// Get the runtime availability for a particular version of Swift (5.0+).
   AvailabilityContext

lib/AST/Availability.cpp

@@ -488,6 +488,10 @@ AvailabilityContext ASTContext::getSwift56Availability() {
   }
 }
 
+AvailabilityContext ASTContext::getSwift57Availability() {
+  return getSwiftFutureAvailability();
+}
+
 AvailabilityContext ASTContext::getSwiftFutureAvailability() {
   auto target = LangOpts.Target;
 
@@ -516,6 +520,7 @@ ASTContext::getSwift5PlusAvailability(llvm::VersionTuple swiftVersion) {
     case 4: return getSwift54Availability();
     case 5: return getSwift55Availability();
     case 6: return getSwift56Availability();
+    case 7: return getSwift57Availability();
     default: break;
     }
   }