The use of file types as function result types is not permitted in Delphi.
program Produce; function OpenFile(Name: string): File; begin end; begin end.
A file cannot be returned from a function.
program Solve; procedure OpenFile(Name: string; var F: File); begin end; begin end.
The file can be ‘returned’ as a variable parameter. You can allocate a file dynamically and return a pointer to it as an alternative.