Function formatComponentName

packages/runtime-core/src/component.ts:1226–1260

(
  instance: ComponentInternalInstance | null,
  Component: ConcreteComponent,
  isRoot = false,
)

}

export function formatComponentName(
  instance: ComponentInternalInstance | null,
  Component: ConcreteComponent,
  isRoot = false,
): string {
  let name = getComponentName(Component)
  if (!name && Component.__file) {
    const match = Component.__file.match(/([^/\\]+)\.\w+$/)
    if (match) {
      name = match[1]
    }
  }

  if (!name && instance) {
    // try to infer the name based on reverse resolution
    const inferFromRegistry = (
      registry: Record<string, any> | undefined | null,
    ) => {
      for (const key in registry) {
        if (registry[key] === Component) {
          return key
        }
      }
    }
    name =
      inferFromRegistry(instance.components) ||
      (instance.parent &&
        inferFromRegistry(
          (instance.parent.type as ComponentOptions).components,
        )) ||
      inferFromRegistry(instance.appContext.components)
  }

  return name ? classify(name) : isRoot ? `App` : `Anonymous`
}

export function isClassComponent(value: unknown): value is ClassComponent {
  return isFunction(value) && '__vccOpts' in value