Attribute.FloatingSourceval declare :
string ->
'a Context.t ->
(Astlib.Ast_500.Parsetree.payload, 'b, 'c) Ast_pattern.t ->
'b ->
('a, 'c) tval convert_res :
('a, 'b) t list ->
'a ->
('b option, Location.Error.t Stdppx.NonEmptyList.t) result