fix: Removing duplicates breaks in TypeScript

fixes #3016

Author: yesl-kim

src/rules/no-duplicates.js

@@ -132,6 +132,7 @@ function getFix(first, rest, sourceCode, context) {
   const shouldAddDefault = getDefaultImportName(first) == null && defaultImportNames.size === 1;
   const shouldAddSpecifiers = specifiers.length > 0;
   const shouldRemoveUnnecessary = unnecessaryImports.length > 0;
+  const preferInline = context.options[0] && context.options[0]['prefer-inline'];
 
   if (!(shouldAddDefault || shouldAddSpecifiers || shouldRemoveUnnecessary)) {
     return undefined;
@@ -157,7 +158,6 @@ function getFix(first, rest, sourceCode, context) {
       ([result, needsComma, existingIdentifiers], specifier) => {
         const isTypeSpecifier = specifier.importNode.importKind === 'type';
 
-        const preferInline = context.options[0] && context.options[0]['prefer-inline'];
         // a user might set prefer-inline but not have a supporting TypeScript version.  Flow does not support inline types so this should fail in that case as well.
         if (preferInline && (!typescriptPkg || !semver.satisfies(typescriptPkg.version, '>= 4.5'))) {
           throw new Error('Your version of TypeScript does not support inline type imports.');
@@ -186,6 +186,17 @@ function getFix(first, rest, sourceCode, context) {
 
     const fixes = [];
 
+    if (shouldAddSpecifiers && preferInline && first.importKind === 'type') {
+      // `import type {a} from './foo'` → `import {type a} from './foo'`
+      const typeIdentifierToken = tokens.find((token) => token.type === 'Identifier' && token.value === 'type');
+      fixes.push(fixer.removeRange([typeIdentifierToken.range[0], typeIdentifierToken.range[1] + 1]));
+
+      const firstIdentifierTokens = tokens.filter((token) => firstExistingIdentifiers.has(token.value));
+      for (const identifier of firstIdentifierTokens) {
+        fixes.push(fixer.replaceTextRange([identifier.range[0], identifier.range[1]], `type ${identifier.value}`));
+      }
+    }
+
     if (shouldAddDefault && openBrace == null && shouldAddSpecifiers) {
       // `import './foo'` → `import def, {...} from './foo'`
       fixes.push(

tests/src/rules/no-duplicates.js

@@ -704,6 +704,24 @@ context('TypeScript', function () {
             },
           ],
         }),
+        test({
+          code: "import type {x} from 'foo'; import {type y} from 'foo'",
+          ...parserConfig,
+          options: [{ 'prefer-inline': true }],
+          output: `import {type x,type y} from 'foo'; `,
+          errors: [
+            {
+              line: 1,
+              column: 22,
+              message: "'foo' imported multiple times.",
+            },
+            {
+              line: 1,
+              column: 50,
+              message: "'foo' imported multiple times.",
+            },
+          ],
+        }),
         test({
           code: "import {type x} from 'foo'; import type {y} from 'foo'",
           ...parserConfig,