patch 9.0.1906: Vim9: Interfaces should not support class methods and variables Commit: https://github.com/vim/vim/commit/92d9ee5f4ca0d2de04c39afbafc7609da43fb2e9 Author: Yegappan Lakshmanan <yegappan@yahoo.com> Date: Sun Sep 17 17:03:19 2023 +0200 patch 9.0.1906: Vim9: Interfaces should not support class methods and variables Problem: Vim9: Interfaces should not support class methods and variables Solution: Make sure interface follow the interface specification Vim9 interface changes to follow the new interface specification: 1) An interface can have only read-only and read-write instance variables. 2) An interface can have only public instance methods. 3) An interface cannot have class variables and class methods. 4) An interface cannot have private instance variables and private instance methods. 5) A interface can extend another interface using "extends". The sub-interface gets all the variables and methods in the super interface. That means: - Interfaces should not support class methods and variables. - Adjust error numbers and add additional tests. - Interface methods can be defined in one of the super classes. - Interface variables can be defined in one of the super classes. and instance variables can be repeated in sub interfaces. - Check the class variable types with the type in interface. closes: #13100 Signed-off-by: Christian Brabandt <cb@256bit.org> Co-authored-by: Yegappan Lakshmanan <yegappan@yahoo.com>