openapi-gen ignores +listType/+listMapKey markers on named slice types (type Foo []Bar), emitting atomic lists

[npinaeva]

+listType=map / +listMapKey placed on a named slice type declaration (type Foo []Bar) is honored by controller-gen (CRD gets
x-kubernetes-list-type: map) but dropped by openapi-gen — so the apply/structured-merge-diff schema produced by applyconfiguration-gen comes out atomic. When the identical marker is placed on the struct field, all three generators agree.

// +listType=map
// +listMapKey=key
type SelectorsA []Selector          // marker on the type

type Spec struct {
    SelectorsFromType SelectorsA `json:"selectorsFromType,omitempty"`

    // +listType=map
    // +listMapKey=key
    SelectorsOnField []Selector `json:"selectorsOnField,omitempty"`     // marker on the FIELD
}

Full CRD is here https://github.com/npinaeva/openapi-bug/blob/main/api/v1/types.go

CRD is generated correctly https://github.com/npinaeva/openapi-bug/blob/main/crds/example.io_examples.yaml

selectorsFromType:
  ...
  x-kubernetes-list-map-keys: [key]
  x-kubernetes-list-type: map
selectorsOnField:
  ...
  x-kubernetes-list-map-keys: [key]
  x-kubernetes-list-type: map

But openapi-gen dropped the type marker
https://github.com/npinaeva/openapi-bug/blob/main/api/v1/openapi/zz_generated.openapi.go

                                  Properties: map[string]spec.Schema{
					"selectorsFromType": {
						SchemaProps: spec.SchemaProps{
							Description: "Variant A: field references a named slice type whose *type* carries the markers.",
							Type:        []string{"array"},
							Items: &spec.SchemaOrArray{
								Schema: &spec.Schema{
									SchemaProps: spec.SchemaProps{
										Ref: ref(v1.Selector{}.OpenAPIModelName()),
									},
								},
							},
						},
					},
					"selectorsOnField": {
						VendorExtensible: spec.VendorExtensible{
							Extensions: spec.Extensions{
								"x-kubernetes-list-map-keys": []interface{}{
									"key",
								},
								"x-kubernetes-list-type": "map",
							},
						},
						SchemaProps: spec.SchemaProps{
							Description: "Variant B: same element type, but markers on the FIELD.",
							Type:        []string{"array"},
							Items: &spec.SchemaOrArray{
								Schema: &spec.Schema{
									SchemaProps: spec.SchemaProps{
										Ref: ref(v1.Selector{}.OpenAPIModelName()),
									},
								},
							},
						},
					},
				},

Looks like

kube-openapi/pkg/generators/openapi.go

Line 756 in d427ff9

func (g openAPITypeWriter) generateMemberExtensions(m *types.Member, parent *types.Type, otherExtensions map[string]interface{}) error {

ignores aliases

[Harsh-128]

I'd like to work on this issue. I'll start by reproducing the problem and adding a regression test before working on the fix.