any(nil) is not equal to nil, should cast it as its original type

[AilinKid]

Bug Report

Please answer these questions before submitting your issue. Thanks!

func (col *Column) Equals(other any) bool {
	if other == nil {. // false
		return false
	}
        col2, ok := other.(*Column)
        // ok will be true
        // then col2 == nil is true 

when we pass var s *Column = nil into as other with type any here, we found it doesn't equal to nil anymore, unless we downcast it with *Column type before equaling with nil

1. Minimal reproduce step (Required)

2. What did you expect to see? (Required)

as mentioned
suggestion way

func (col *Column) Equals(other any) bool {
    col2, ok := other.(*Column)
    if !ok {
        return false
    }
    if col == nil {
        return col2==nil
    }
    if col2 == nil {
        return false
    }
    // normal equals logic appended

3. What did you see instead (Required)

as mentioned

4. What is your TiDB version? (Required)

master

[King-Dylan]

/severity minor

[ti-chi-bot]

@King-Dylan: The label(s) severity/minor cannot be applied. These labels are supported: fuzz/sqlancer, challenge-program, compatibility-breaker, first-time-contributor, contribution, good first issue, correctness, duplicate, proposal, security, needs-more-info, needs-cherry-pick-release-5.4, needs-cherry-pick-release-6.1, needs-cherry-pick-release-6.5, needs-cherry-pick-release-7.1, needs-cherry-pick-release-7.5, needs-cherry-pick-release-8.1, needs-cherry-pick-release-8.5, affects-5.4, affects-6.1, affects-6.5, affects-7.1, affects-7.5, affects-8.1, affects-8.4, affects-8.5, may-affects-5.4, may-affects-6.1, may-affects-6.5, may-affects-7.1, may-affects-7.5, may-affects-8.1, may-affects-8.5.

In response to this:

/label severity/minor

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.