Generated injection code is broken when there's a mismatch in type

[carlisia]

There is a problem with the injection code logic where if a type ReferencePolicyList struct contains an item such as the first one below the generated code will work, but if the included item is of a different type, then the code generated is of one type but expects the other.

• Items []ReferencePolicy - works as an element of type ReferencePolicyList struct
• Items []ReferenceGrant - does not work as an element of type ReferencePolicyList struct

We got to see this happening in this PR:
⬆️ Bump Gateway API version to v0.5.0-rc1 by carlisia · Pull Request #315 · knative-sandbox/net-gateway-api

We "fixed" it by deleting this piece of the generated code after the script was run, since it wasn't actually being used.

/area networking
/kind bug

This works:

pkg/informer.go at 177751338ddc41979885ecf39679f5a900c00111 · knative/pkg

type [ReferencePolicyList](https://github.com/kubernetes-sigs/gateway-api/blob/v0.4.0/apis/v1alpha2/referencepolicy_types.go#L54) [¶](https://pkg.go.dev/sigs.k8s.io/gateway-api@v0.4.0/apis/v1alpha2?utm_source=gopls#ReferencePolicyList)
type ReferencePolicyList struct {
	[metav1](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1).[TypeMeta](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#TypeMeta) `json:",inline"`
	[metav1](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1).[ListMeta](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#ListMeta) `json:"metadata,omitempty"`
	Items           [][ReferencePolicy](https://pkg.go.dev/sigs.k8s.io/gateway-api@v0.4.0/apis/v1alpha2?utm_source=gopls#ReferencePolicy) `json:"items"`
}

This does not work:

type [ReferencePolicyList](https://github.com/kubernetes-sigs/gateway-api/blob/v0.5.0-rc1/apis/v1alpha2/referencepolicy_types.go#L58) [¶](https://pkg.go.dev/sigs.k8s.io/gateway-api@v0.5.0-rc1/apis/v1alpha2?utm_source=gopls#ReferencePolicyList)
type ReferencePolicyList struct {
	[metav1](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1).[TypeMeta](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#TypeMeta) `json:",inline"`
	[metav1](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1).[ListMeta](https://pkg.go.dev/k8s.io/apimachinery/pkg/apis/meta/v1#ListMeta) `json:"metadata,omitempty"`
	Items           [][ReferenceGrant](https://pkg.go.dev/sigs.k8s.io/gateway-api@v0.5.0-rc1/apis/v1alpha2?utm_source=gopls#ReferenceGrant) `json:"items"`
}

# knative.dev/net-gateway-api/pkg/client/gatewayapi/injection/informers/apis/v1alpha2/referencepolicy
pkg/client/gatewayapi/injection/informers/apis/v1alpha2/referencepolicy/referencepolicy.go:107:15: cannot use &lo.Items[idx] (type *"sigs.k8s.io/gateway-api/apis/v1alpha2".ReferenceGrant) as type *"sigs.k8s.io/gateway-api/apis/v1alpha2".ReferencePolicy in append

# knative.dev/net-gateway-api/pkg/client/gatewayapi/injection/informers/apis/v1alpha2/referencepolicy/filtered
pkg/client/gatewayapi/injection/informers/apis/v1alpha2/referencepolicy/filtered/referencepolicy.go:126:15: cannot use &lo.Items[idx] (type *"sigs.k8s.io/gateway-api/apis/v1alpha2".ReferenceGrant) as type *"sigs.k8s.io/gateway-api/apis/v1alpha2".ReferencePolicy in append

/assign @dprotaso

Expected Behavior

Actual Behavior

Steps to Reproduce the Problem

Additional Info

[dprotaso]

Hopefully they can fix the type to what it was before

kubernetes-sigs/gateway-api#1239

Otherwise I'll make changes to the injection-gen

[evankanderson]

If we fix this on the Knative side, the code is probably here: https://github.com/knative/pkg/blob/main/codegen/cmd/injection-gen/generators/client.go#L542

[dprotaso]

Gateway API change merged - so we should be good

[carlisia]

Thanks for fixing this @dprotaso! I was convinced that had been done intentionally 😆