fix(eslint-plugin): [no-unused-vars] ignore imports used only as types (#9694)

* fix(eslint-plugin): [no-unused-vars] ignore imports used only as types

* chore(eslint-plugin): [no-unused-vars] avoid extra calculation before continue

Author: jakebailey

packages/eslint-plugin/src/rules/no-unused-vars.ts

@@ -579,6 +579,19 @@ export default createRule<Options, MessageIds>({
         for (const unusedVar of unusedVars) {
           // Report the first declaration.
           if (unusedVar.defs.length > 0) {
+            const usedOnlyAsType = unusedVar.references.some(ref =>
+              referenceContainsTypeQuery(ref.identifier),
+            );
+
+            const isImportUsedOnlyAsType =
+              usedOnlyAsType &&
+              unusedVar.defs.some(
+                def => def.type === DefinitionType.ImportBinding,
+              );
+            if (isImportUsedOnlyAsType) {
+              continue;
+            }
+
             const writeReferences = unusedVar.references.filter(
               ref =>
                 ref.isWrite() &&
@@ -589,10 +602,6 @@ export default createRule<Options, MessageIds>({
               ? writeReferences[writeReferences.length - 1].identifier
               : unusedVar.identifiers[0];
 
-            const usedOnlyAsType = unusedVar.references.some(ref =>
-              referenceContainsTypeQuery(ref.identifier),
-            );
-
             const messageId = usedOnlyAsType ? 'usedOnlyAsType' : 'unusedVar';
 
             const { start } = id.loc;

packages/eslint-plugin/tests/rules/no-unused-vars/no-unused-vars.test.ts

@@ -1173,6 +1173,16 @@ export type Foo = typeof foo;
 
 export const bar = (): Foo => foo;
     `,
+    `
+import { SomeType } from 'foo';
+
+export const value = 1234 as typeof SomeType;
+    `,
+    `
+import { foo } from 'foo';
+
+export type Bar = typeof foo;
+    `,
   ],
 
   invalid: [
@@ -2256,26 +2266,5 @@ export const x = _Foo;
         },
       ],
     },
-    {
-      code: `
-        import { foo } from 'foo';
-
-        export type Bar = typeof foo;
-      `,
-      errors: [
-        {
-          messageId: 'usedOnlyAsType',
-          data: {
-            varName: 'foo',
-            action: 'defined',
-            additional: '',
-          },
-          line: 2,
-          column: 18,
-          endLine: 2,
-          endColumn: 21,
-        },
-      ],
-    },
   ],
 });