chore(compiler-core): improve types (#2428)

packages/compiler-core/src/parse.ts

@@ -29,6 +29,13 @@ import {
 type OptionalOptions = 'isNativeTag' | 'isBuiltInComponent'
 type MergedParserOptions = Omit<Required<ParserOptions>, OptionalOptions> &
   Pick<ParserOptions, OptionalOptions>
+type AttributeValue =
+  | {
+      content: string
+      isQuoted: boolean
+      loc: SourceLocation
+    }
+  | undefined
 
 // The default decoder only provides escapes for characters reserved as part of
 // the template syntax, and is only used if the custom renderer did not provide
@@ -590,13 +597,7 @@ function parseAttribute(
   advanceBy(context, name.length)
 
   // Value
-  let value:
+  let value: AttributeValue = undefined
-    | {
-        content: string
-        isQuoted: boolean
-        loc: SourceLocation
-      }
-    | undefined = undefined
 
   if (/^[\t\r\n\f ]*=/.test(context.source)) {
     advanceSpaces(context)
@@ -702,15 +703,7 @@ function parseAttribute(
   }
 }
 
-function parseAttributeValue(
+function parseAttributeValue(context: ParserContext): AttributeValue {
-  context: ParserContext
-):
-  | {
-      content: string
-      isQuoted: boolean
-      loc: SourceLocation
-    }
-  | undefined {
   const start = getCursor(context)
   let content: string