fix(component): prioritize registered component over implicit self-reference via filename

ref: #2827

packages/runtime-core/src/helpers/resolveAssets.ts

@@ -16,8 +16,11 @@ const DIRECTIVES = 'directives'
 /**
  * @private
  */
-export function resolveComponent(name: string): ConcreteComponent | string {
-  return resolveAsset(COMPONENTS, name) || name
+export function resolveComponent(
+  name: string,
+  maybeSelfReference?: boolean
+): ConcreteComponent | string {
+  return resolveAsset(COMPONENTS, name, true, maybeSelfReference) || name
 }
 
 export const NULL_DYNAMIC_COMPONENT = Symbol()
@@ -48,7 +51,8 @@ export function resolveDirective(name: string): Directive | undefined {
 function resolveAsset(
   type: typeof COMPONENTS,
   name: string,
-  warnMissing?: boolean
+  warnMissing?: boolean,
+  maybeSelfReference?: boolean
 ): ConcreteComponent | undefined
 // overload 2: directives
 function resolveAsset(
@@ -59,20 +63,15 @@ function resolveAsset(
 function resolveAsset(
   type: typeof COMPONENTS | typeof DIRECTIVES,
   name: string,
-  warnMissing = true
+  warnMissing = true,
+  maybeSelfReference = false
 ) {
   const instance = currentRenderingInstance || currentInstance
   if (instance) {
     const Component = instance.type
 
-    // self name has highest priority
+    // explicit self name has highest priority
     if (type === COMPONENTS) {
-      // special self referencing call generated by compiler
-      // inferred from SFC filename
-      if (name === `_self`) {
-        return Component
-      }
-
       const selfName = getComponentName(Component)
       if (
         selfName &&
@@ -90,9 +89,16 @@ function resolveAsset(
       resolve(instance[type] || (Component as ComponentOptions)[type], name) ||
       // global registration
       resolve(instance.appContext[type], name)
+
+    if (!res && maybeSelfReference) {
+      // fallback to implicit self-reference
+      return Component
+    }
+
     if (__DEV__ && warnMissing && !res) {
       warn(`Failed to resolve ${type.slice(0, -1)}: ${name}`)
     }
+
     return res
   } else if (__DEV__) {
     warn(