Fix +listType marker not working on type alias fields

Include underlying type info (array/object) in schema for slice/map
type aliases, allowing field-level markers like +listType to work.

Fixes #988

Author: sivchari

pkg/crd/schema.go

@@ -306,26 +306,32 @@ func localNamedToSchema(ctx *schemaContext, ident *ast.Ident) *apiextensionsv1.J
 	ctx.requestSchema(pkgPath, typeNameInfo.Name())
 	link := TypeRefLink(pkgPath, typeNameInfo.Name())
 
+	// For type aliases to slice/map types, include the underlying type information
+	// so that markers like +listType can be applied at the field level.
+	// This mirrors the behavior for basic type aliases (see above).
+	props := &apiextensionsv1.JSONSchemaProps{
+		Ref: &link,
+	}
+
 	// In cases where we have a named type, apply the type and format from the named schema
 	// to allow markers that need this information to apply correctly.
-	var typ, fmt string
 	if namedInfo, isNamed := typeInfo.(*types.Named); isNamed {
-		// We don't want/need to do this for structs, maps, or arrays.
-		// These are already handled in infoToSchema if they have custom marshalling.
-		if _, isBasic := namedInfo.Underlying().(*types.Basic); isBasic {
+		switch namedInfo.Underlying().(type) {
+		case *types.Slice:
+			props.Type = "array"
+		case *types.Map:
+			props.Type = "object"
+		case *types.Basic:
+			// We don't want/need to do this for structs, maps, or arrays.
+			// These are already handled in infoToSchema if they have custom marshalling.
 			namedTypeInfo := ctx.schemaRequester.LookupType(ctx.pkg, namedInfo.Obj().Name())
-
 			namedSchema := infoToSchema(ctx.ForInfo(namedTypeInfo))
-			typ = namedSchema.Type
-			fmt = namedSchema.Format
+			props.Type = namedSchema.Type
+			props.Format = namedSchema.Format
 		}
 	}
 
-	return &apiextensionsv1.JSONSchemaProps{
-		Type:   typ,
-		Format: fmt,
-		Ref:    &link,
-	}
+	return props
 }
 
 // namedSchema creates a schema (ref) for an explicitly external type reference.
@@ -340,10 +346,19 @@ func namedToSchema(ctx *schemaContext, named *ast.SelectorExpr) *apiextensionsv1
 	nonVendorPath := loader.NonVendorPath(typeNameInfo.Pkg().Path())
 	ctx.requestSchema(nonVendorPath, typeNameInfo.Name())
 	link := TypeRefLink(nonVendorPath, typeNameInfo.Name())
-	return &apiextensionsv1.JSONSchemaProps{
+	// For type aliases to slice/map types, include the underlying type information
+	// so that markers like +listType can be applied at the field level.
+	props := &apiextensionsv1.JSONSchemaProps{
 		Ref: &link,
 	}
+	switch typeInfoRaw.Underlying().(type) {
+	case *types.Slice:
+		props.Type = "array"
+	case *types.Map:
+		props.Type = "object"
+	}
 	// NB(directxman12): we special-case things like resource.Quantity during the "collapse" phase.
+	return props
 }
 
 // arrayToSchema creates a schema for the items of the given array, dealing appropriately

pkg/crd/testdata/cronjob_types.go

@@ -207,6 +207,12 @@ type CronJobSpec struct {
 	// This tests that associative lists work via a nested type.
 	NestedAssociativeList NestedAssociativeList `json:"nestedassociativeList"`
 
+	// This tests that +listType can be applied at the field level for type aliases (issue #988).
+	// +listType=map
+	// +listMapKey=name
+	// +listMapKey=secondary
+	FieldLevelListType ConditionsWithoutMarker `json:"fieldLevelListType"`
+
 	// A map that allows different actors to manage different fields
 	// +mapType=granular
 	MapOfInfo map[string][]byte `json:"mapOfInfo"`
@@ -544,6 +550,10 @@ type NestedAssociativeList []AssociativeType
 // +mapType=granular
 type NestedMapOfInfo map[string][]byte
 
+// ConditionsWithoutMarker is a type alias to a slice without type-level markers.
+// This tests that +listType can be applied at the field level (issue #988).
+type ConditionsWithoutMarker []AssociativeType
+
 // +kubebuilder:validation:MinLength=4
 // This tests that markers that are allowed on both fields and types are applied to types
 type LongerString string

pkg/crd/testdata/testdata.kubebuilder.io_cronjobs.yaml

@@ -235,6 +235,27 @@ spec:
                   This tests that field-level overrides are handled correctly
                   for local type aliases.
                 type: string
+              fieldLevelListType:
+                description: 'This tests that +listType can be applied at the field
+                  level for type aliases (issue #988).'
+                items:
+                  properties:
+                    foo:
+                      type: string
+                    name:
+                      type: string
+                    secondary:
+                      type: integer
+                  required:
+                  - foo
+                  - name
+                  - secondary
+                  type: object
+                type: array
+                x-kubernetes-list-map-keys:
+                - name
+                - secondary
+                x-kubernetes-list-type: map
               fieldLevelLocalDeclarationOverride:
                 allOf:
                 - minLength: 4
@@ -9721,6 +9742,7 @@ spec:
             - explicitlyRequiredK8s
             - explicitlyRequiredKubebuilder
             - explicitlyRequiredKubernetes
+            - fieldLevelListType
             - float64WithValidations
             - floatWithValidations
             - foo