Pointer: Add generic Pointer func

[alvaroaleman]

This adds a new, generic pointer func to the pointer package.

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[MadhavJivrajani]

I think we'll need to update the golangci-lint version and explicitly mention 1.18:

docker run --rm -v `pwd`:/go/src/k8s.io/klog -w /go/src/k8s.io/klog \
            golangci/golangci-lint:v1.45.0 golangci-lint run --go 1.18 --disable-all -v \
            -E govet -E misspell -E gofmt -E ineffassign -E golint

See golangci/golangci-lint#2649 for more details.

[liggitt]

does this require all consumers of k8s.io/utils to set go1.18 in their go.mod files, or just compile with go 1.18?

[alvaroaleman]

@thockin the tests in ./internal/third_party/forked/golang/net do not pass on go versions > 1.16. Is this known? Can you have a look?

The problem is that the test calls IP.UnmarshalText which uses the stdlibs ParseIP which inhibits the behavior you apparently wanted to supress with the fork...?

I've added a commit that uses a downstream IPUnmarshalText but I think you should have a look and check what exactly is expected here.

[alvaroaleman]

@liggitt I just tested, it works fine when the importing project sets go 1.17 but using a go 1.18 compiler...Out of curiosity, why do we care? So importing projects that do not use this package can still use an older compiler?

[liggitt]

Out of curiosity, why do we care? So importing projects that do not use this package can still use an older compiler?

changing go.mod to 1.17+ messes up the require directives in ways that break our dependency analysis tooling (xref golang/go#47648)

[liggitt]

So importing projects that do not use this package can still use an older compiler?

also, we don't tag versions of k8s.io/utils and maintain multiple branches, so I probably wouldn't expect us to start using go1.18 features until go1.18 was the oldest supported go version (when go1.19 is released)

[alvaroaleman]

I am sorry the PR has so many unrelated changes now, all of them are fallout from updating the go version:

• The github workflow never used the configured go version, because it referred an undefined variable from the matrix (go-version vs go-versions)
• pkg/inotify doesn't pass go vet on go 1.17+ because it calls t.Fatalf from a goroutine
• forked/golang/net doesn't pass tests on go 1.17+, precicely because of the change in behavior it is supposed to prevent
• gofmt needed updating in a couple of places to add the go:build directives added in go .17
• golangci-lint added support for go 1.18 but they didn't change the compiler version in the released docker image that does that, and there is no released docker image compiled with 1.18. Thx @MadhavJivrajani for the tip. The unreleased change to update the compiler for the image is fix: update base images to go1.18 golangci/golangci-lint#2661

[euroelessar]

Just passing by, but can you consider the following changes, please?

1. Use // +build go1.18 build tag in a file with generic implementations to keep compatibility with lower golang versions
2. In case of golang 1.18, implement existing methods using generic one, e.g. var Int = Pointer[int]
3. Keep an existing implementation for versions below 1.17 behind !go1.18 build tag, this way an older implementation can be deleted once 1.18 is the lowest supported version
4. Provide an implementation for Deref and Equal methods as well

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@alvaroaleman: PR needs rebase.

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@k8s-triage-robot: Closed this PR.

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