[SwiftToCxx] Adding _Nullable to avoid warnings

Author: Robertorosmaninho

lib/PrintAsClang/PrintClangFunction.cpp

@@ -475,7 +475,7 @@ ClangRepresentation DeclAndTypeClangFunctionPrinter::printFunctionSignature(
         }
       } else if (param.role ==  AdditionalParam::Role::Error) {
         os << "SWIFT_ERROR_RESULT ";
-        os << "void ** _error";
+        os << "void * _Nullable * _Nullable _error";
       } else if (param.role == AdditionalParam::Role::GenericRequirement) {
         os << "void * _Nonnull ";
         if (param.genericRequirement->Protocol)

test/Interop/SwiftToCxx/functions/swift-functions-errors.swift

@@ -8,8 +8,8 @@
 
 // CHECK-LABEL: namespace _impl {
 
-// CHECK: SWIFT_EXTERN void $s9Functions18emptyThrowFunctionyyKF(SWIFT_CONTEXT void * _Nonnull _self, SWIFT_ERROR_RESULT void ** _error) SWIFT_CALL; // emptyThrowFunction()
-// CHECK: SWIFT_EXTERN void $s9Functions13throwFunctionyyKF(SWIFT_CONTEXT void * _Nonnull _self, SWIFT_ERROR_RESULT void ** _error) SWIFT_CALL; // throwFunction()
+// CHECK: SWIFT_EXTERN void $s9Functions18emptyThrowFunctionyyKF(SWIFT_CONTEXT void * _Nonnull _self, SWIFT_ERROR_RESULT void * _Nullable * _Nullable _error) SWIFT_CALL; // emptyThrowFunction()
+// CHECK: SWIFT_EXTERN void $s9Functions13throwFunctionyyKF(SWIFT_CONTEXT void * _Nonnull _self, SWIFT_ERROR_RESULT void * _Nullable * _Nullable _error) SWIFT_CALL; // throwFunction()
 
 // CHECK: }