Basic type alias panic on shouldBeCopied()

[potatogopher]

When generating DeepCopy, DeepCopyInto and DeepCopyObject, a panic occurs with the following error:

panic: interface conversion: types.Type is *types.Basic, not *types.Named

goroutine 1 [running]:
sigs.k8s.io/controller-tools/pkg/deepcopy.shouldBeCopied(0x140002584c0, 0x14002327080)
	/Users/me/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/deepcopy/traverse.go:622

This occurs when using an alias with a basic type:

type MyAlias = string

Things pass when using the following:

type MyAlias string

While checking the internals it seems like the intention is to skip types that are eventually basic but nothing about types that are "immediately" basic.

I wanted to propose adding a check for if typeInfo is a basic type before getting the underlying pointer of the named type to support an alias.

func shouldBeCopied(pkg *loader.Package, info *markers.TypeInfo) bool {
	if !ast.IsExported(info.Name) {
		return false
	}

	typeInfo := pkg.TypesInfo.TypeOf(info.RawSpec.Name)
	if typeInfo == types.Typ[types.Invalid] {
		pkg.AddError(loader.ErrFromNode(fmt.Errorf("unknown type: %s", info.Name), info.RawSpec))
		return false
	}

+	if _, isBasic := typeInfo.(*types.Basic); isBasic {
+		return false
+	}

	// according to gengo, everything named is an alias, except for an alias to a pointer,
	// which is just a pointer, afaict.  Just roll with it.
	if asPtr, isPtr := typeInfo.(*types.Named).Underlying().(*types.Pointer); isPtr {
		typeInfo = asPtr
	}

	lastType := typeInfo
	if _, isNamed := typeInfo.(*types.Named); isNamed {
		// if it has a manual deepcopy or deepcopyinto, we're fine
		if hasAnyDeepCopyMethod(pkg, typeInfo) {
			return true
		}

		for underlyingType := typeInfo.Underlying(); underlyingType != lastType; lastType, underlyingType = underlyingType, underlyingType.Underlying() {
			// if it has a manual deepcopy or deepcopyinto, we're fine
			if hasAnyDeepCopyMethod(pkg, underlyingType) {
				return true
			}

			// aliases to other things besides basics need copy methods
			// (basics can be straight-up shallow-copied)
			if _, isBasic := underlyingType.(*types.Basic); !isBasic {
				return true
			}
		}
	}

	// structs are the only thing that's not a basic that's copiable by default
	_, isStruct := lastType.(*types.Struct)
	return isStruct
}

[k8s-triage-robot]

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/lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues.

This bot triages un-triaged issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
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/lifecycle rotten

[k8s-triage-robot]

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
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/close not-planned

[k8s-ci-robot]

@k8s-triage-robot: Closing this issue, marking it as "Not Planned".

In response to this:

The Kubernetes project currently lacks enough active contributors to adequately respond to all issues and PRs.

This bot triages issues according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

You can:

• Reopen this issue with /reopen
• Mark this issue as fresh with /remove-lifecycle rotten
• Offer to help out with Issue Triage

Please send feedback to sig-contributor-experience at kubernetes/community.

/close not-planned

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[sbueringer]

/reopen /lifecycle frozen

Seems reasonable at a first glance

[k8s-ci-robot]

@sbueringer: Reopened this issue.

In response to this:

/reopen /lifecycle frozen

Seems reasonable at a first glance

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