perf(utils): faster ImportDeclaration detect

src/rules/namespace.ts

@@ -151,7 +151,10 @@ export = createRule<[Options], MessageId>({
 
       // same as above, but does not add names to local map
       ExportNamespaceSpecifier(namespace) {
-        const declaration = importDeclaration(context, namespace)
+        const declaration = importDeclaration(
+          context,
+          namespace as TSESTree.ImportDefaultSpecifier,
+        )
 
         const imports = ExportMap.get(declaration.source.value, context)
         if (imports == null) {

src/utils/import-declaration.ts

@@ -1,11 +1,15 @@
+import { AST_NODE_TYPES } from '@typescript-eslint/utils'
 import type { TSESTree } from '@typescript-eslint/utils'
 
 import type { RuleContext } from '../types'
 
 export const importDeclaration = (
   context: RuleContext,
-  node: TSESTree.Node,
+  node: TSESTree.ImportDefaultSpecifier,
 ) => {
+  if (node.parent && node.parent.type === AST_NODE_TYPES.ImportDeclaration) {
+    return node.parent
+  }
   const ancestors = context.sourceCode.getAncestors(node)
   return ancestors[ancestors.length - 1] as TSESTree.ImportDeclaration
 }

src/utils/resolve.ts

@@ -153,10 +153,6 @@ function fullResolve(
     return { found: true, path: cachedPath }
   }
 
-  function cache(resolvedPath: string | null) {
-    fileExistsCache.set(cacheKey, resolvedPath)
-  }
-
   function withResolver(resolver: Resolver, config: unknown) {
     if (resolver.interfaceVersion === 2) {
       return resolver.resolve(modulePath, sourceFile, config)
@@ -195,7 +191,7 @@ function fullResolve(
     }
 
     // else, counts
-    cache(resolved.path as string | null)
+    fileExistsCache.set(cacheKey, resolved.path as string | null)
     return resolved
   }