fix gts type aware by emulating them to ts files

set our own ts.sys with ts.setSys
typescript-eslint has handling for a lot of scenarios for file changes and project changes etc
use mts extension to keep same offsets
we also sync the mts with the gts files

lib/parsers/ts-utils.js

@@ -0,0 +1,117 @@
+const fs = require('node:fs');
+const { transformForLint } = require('./transform');
+const babel = require('@babel/core');
+const { replaceRange } = require('./transform');
+
+let patchTs, replaceExtensions, syncMtsGtsSourceFiles, typescriptParser;
+
+try {
+  const ts = require('typescript');
+  typescriptParser = require('@typescript-eslint/parser');
+  patchTs = function patchTs() {
+    const sys = { ...ts.sys };
+    const newSys = {
+      ...ts.sys,
+      readDirectory(...args) {
+        const results = sys.readDirectory.call(this, ...args);
+        return [
+          ...results,
+          ...results.filter((x) => x.endsWith('.gts')).map((f) => f.replace(/\.gts$/, '.mts')),
+        ];
+      },
+      fileExists(fileName) {
+        return fs.existsSync(fileName.replace(/\.mts$/, '.gts')) || fs.existsSync(fileName);
+      },
+      readFile(fname) {
+        let fileName = fname;
+        let content = '';
+        try {
+          content = fs.readFileSync(fileName).toString();
+        } catch {
+          fileName = fileName.replace(/\.mts$/, '.gts');
+          content = fs.readFileSync(fileName).toString();
+        }
+        if (fileName.endsWith('.gts')) {
+          content = transformForLint(content).output;
+        }
+        if (
+          (!fileName.endsWith('.d.ts') && fileName.endsWith('.ts')) ||
+          fileName.endsWith('.gts')
+        ) {
+          content = replaceExtensions(content);
+        }
+        return content;
+      },
+    };
+    ts.setSys(newSys);
+  };
+
+  replaceExtensions = function replaceExtensions(code) {
+    let jsCode = code;
+    const babelParseResult = babel.parse(jsCode, {
+      parserOpts: { ranges: true, plugins: ['typescript'] },
+    });
+    const length = jsCode.length;
+    for (const b of babelParseResult.program.body) {
+      if (b.type === 'ImportDeclaration' && b.source.value.endsWith('.gts')) {
+        const value = b.source.value.replace(/\.gts$/, '.mts');
+        const strWrapper = jsCode[b.source.start];
+        jsCode = replaceRange(
+          jsCode,
+          b.source.start,
+          b.source.end,
+          strWrapper + value + strWrapper
+        );
+      }
+    }
+    if (length !== jsCode.length) {
+      throw new Error('bad replacement');
+    }
+    return jsCode;
+  };
+
+  /**
+   *
+   * @param program {ts.Program}
+   */
+  syncMtsGtsSourceFiles = function syncMtsGtsSourceFiles(program) {
+    const sourceFiles = program.getSourceFiles();
+    for (const sourceFile of sourceFiles) {
+      // check for deleted gts files, need to remove mts as well
+      if (sourceFile.path.endsWith('.mts') && sourceFile.isVirtualGts) {
+        const gtsFile = program.getSourceFile(sourceFile.path.replace(/\.mts$/, '.gts'));
+        if (!gtsFile) {
+          sourceFile.version = null;
+        }
+      }
+      if (sourceFile.path.endsWith('.gts')) {
+        /**
+         * @type {ts.SourceFile}
+         */
+        const mtsSourceFile = program.getSourceFile(sourceFile.path.replace(/\.gts$/, '.mts'));
+        if (mtsSourceFile) {
+          const keep = {
+            fileName: mtsSourceFile.fileName,
+            path: mtsSourceFile.path,
+            originalFileName: mtsSourceFile.originalFileName,
+            resolvedPath: mtsSourceFile.resolvedPath,
+          };
+          Object.assign(mtsSourceFile, sourceFile, keep);
+          mtsSourceFile.isVirtualGts = true;
+        }
+      }
+    }
+  };
+} catch {
+  // typescript not available
+  patchTs = () => null;
+  replaceExtensions = (code) => code;
+  syncMtsGtsSourceFiles = () => null;
+}
+
+module.exports = {
+  patchTs,
+  replaceExtensions,
+  syncMtsGtsSourceFiles,
+  typescriptParser
+};

package.json

@@ -68,6 +68,7 @@
     ]
   },
   "dependencies": {
+    "@babel/core": "^7.23.3",
     "@babel/eslint-parser": "^7.22.15",
     "@ember-data/rfc395-data": "^0.0.4",
     "@glimmer/syntax": "^0.85.12",
@@ -116,7 +117,13 @@
     "typescript": "^5.2.2"
   },
   "peerDependencies": {
-    "eslint": ">= 8"
+    "eslint": ">= 8",
+    "typescript": "*"
+  },
+  "peerDependenciesMeta": {
+    "typescript": {
+      "optional": true
+    }
   },
   "engines": {
     "node": "18.* || 20.* || >= 21"

tests/lib/rules-preprocessor/ember_ts/bar.gts

@@ -0,0 +1,5 @@
+export const fortyTwoFromGTS = '42';
+
+<template>
+  {{fortyTwoFromGTS}}
+</template>

tests/lib/rules-preprocessor/ember_ts/baz.ts

@@ -0,0 +1 @@
+export const fortyTwoFromTS = '42';

tests/lib/rules-preprocessor/ember_ts/foo.gts

@@ -0,0 +1,14 @@
+import { fortyTwoFromGTS } from './bar.gts';
+import { fortyTwoFromTS } from './baz.ts';
+
+export const fortyTwoLocal = '42';
+
+const helloWorldFromTS = fortyTwoFromTS[0] === '4' ? 'hello' : 'world';
+const helloWorldFromGTS = fortyTwoFromGTS[0] === '4' ? 'hello' : 'world';
+const helloWorld = fortyTwoLocal[0] === '4' ? 'hello' : 'world';
+//
+<template>
+  {{helloWorldFromGTS}}
+  {{helloWorldFromTS}}
+  {{helloWorld}}
+</template>

tests/lib/rules-preprocessor/gjs-gts-parser-test.js

@@ -9,6 +9,8 @@
 
 const { ESLint } = require('eslint');
 const plugin = require('../../../lib');
+const { writeFileSync, readFileSync, unlinkSync } = require('node:fs');
+const { join } = require('node:path');
 
 const gjsGtsParser = require.resolve('../../../lib/parsers/gjs-gts-parser');
 
@@ -388,18 +390,28 @@ const invalid = [
     code: `
       import Component from '@glimmer/component';
 
+      const foo: any = '';
+
       export default class MyComponent extends Component {
         foo = 'bar';
 
         <template>
           <div></div>${'  '}
+          {{foo}}
         </template>
       }`,
     errors: [
+      {
+        message: 'Unexpected any. Specify a different type.',
+        line: 4,
+        endLine: 4,
+        column: 18,
+        endColumn: 21,
+      },
       {
         message: 'Trailing spaces not allowed.',
-        line: 8,
-        endLine: 8,
+        line: 10,
+        endLine: 10,
         column: 22,
         endColumn: 24,
       },
@@ -765,4 +777,133 @@ describe('multiple tokens in same file', () => {
     expect(resultErrors[2].message).toBe("'bar' is not defined.");
     expect(resultErrors[2].line).toBe(17);
   });
+
+  it('lints while being type aware', async () => {
+    const eslint = new ESLint({
+      ignore: false,
+      useEslintrc: false,
+      plugins: { ember: plugin },
+      overrideConfig: {
+        root: true,
+        env: {
+          browser: true,
+        },
+        plugins: ['ember'],
+        extends: ['plugin:ember/recommended'],
+        overrides: [
+          {
+            files: ['**/*.gts'],
+            parser: 'eslint-plugin-ember/gjs-gts-parser',
+            parserOptions: {
+              project: './tsconfig.eslint.json',
+              tsconfigRootDir: __dirname,
+              extraFileExtensions: ['.gts'],
+            },
+            extends: [
+              'plugin:@typescript-eslint/recommended-requiring-type-checking',
+              'plugin:ember/recommended',
+            ],
+            rules: {
+              'no-trailing-spaces': 'error',
+              '@typescript-eslint/prefer-string-starts-ends-with': 'error',
+            },
+          },
+          {
+            files: ['**/*.ts'],
+            parser: '@typescript-eslint/parser',
+            parserOptions: {
+              project: './tsconfig.eslint.json',
+              tsconfigRootDir: __dirname,
+              extraFileExtensions: ['.gts'],
+            },
+            extends: [
+              'plugin:@typescript-eslint/recommended-requiring-type-checking',
+              'plugin:ember/recommended',
+            ],
+            rules: {
+              'no-trailing-spaces': 'error',
+            },
+          },
+        ],
+        rules: {
+          quotes: ['error', 'single'],
+          semi: ['error', 'always'],
+          'object-curly-spacing': ['error', 'always'],
+          'lines-between-class-members': 'error',
+          'no-undef': 'error',
+          'no-unused-vars': 'error',
+          'ember/no-get': 'off',
+          'ember/no-array-prototype-extensions': 'error',
+          'ember/no-unused-services': 'error',
+        },
+      },
+    });
+
+    let results = await eslint.lintFiles(['**/*.gts', '**/*.ts']);
+
+    let resultErrors = results.flatMap((result) => result.messages);
+    expect(resultErrors).toHaveLength(3);
+
+    expect(resultErrors[0].message).toBe("Use 'String#startsWith' method instead.");
+    expect(resultErrors[0].line).toBe(6);
+
+    expect(resultErrors[1].line).toBe(7);
+    expect(resultErrors[1].message).toBe("Use 'String#startsWith' method instead.");
+
+    expect(resultErrors[2].line).toBe(8);
+    expect(resultErrors[2].message).toBe("Use 'String#startsWith' method instead.");
+
+    const filePath = join(__dirname, 'ember_ts', 'bar.gts');
+    const content = readFileSync(filePath).toString();
+    try {
+      writeFileSync(filePath, content.replace("'42'", '42'));
+
+      results = await eslint.lintFiles(['**/*.gts', '**/*.ts']);
+
+      resultErrors = results.flatMap((result) => result.messages);
+      expect(resultErrors).toHaveLength(2);
+
+      expect(resultErrors[0].message).toBe("Use 'String#startsWith' method instead.");
+      expect(resultErrors[0].line).toBe(6);
+
+      expect(resultErrors[1].line).toBe(8);
+      expect(resultErrors[1].message).toBe("Use 'String#startsWith' method instead.");
+    } finally {
+      writeFileSync(filePath, content);
+    }
+
+    results = await eslint.lintFiles(['**/*.gts', '**/*.ts']);
+
+    resultErrors = results.flatMap((result) => result.messages);
+    expect(resultErrors).toHaveLength(3);
+
+    expect(resultErrors[0].message).toBe("Use 'String#startsWith' method instead.");
+    expect(resultErrors[0].line).toBe(6);
+
+    expect(resultErrors[1].message).toBe("Use 'String#startsWith' method instead.");
+    expect(resultErrors[1].line).toBe(7);
+
+    expect(resultErrors[2].line).toBe(8);
+    expect(resultErrors[2].message).toBe("Use 'String#startsWith' method instead.");
+
+    try {
+      unlinkSync(filePath);
+      await new Promise(resolve  => setTimeout(resolve, 100));
+      results = await eslint.lintFiles(['**/*.gts', '**/*.ts']);
+
+      resultErrors = results.flatMap((result) => result.messages);
+      expect(resultErrors).toHaveLength(3);
+
+      expect(resultErrors[0].message).toBe("Use 'String#startsWith' method instead.");
+      expect(resultErrors[0].line).toBe(6);
+
+      expect(resultErrors[1].message).toBe("Use 'String#startsWith' method instead.");
+      expect(resultErrors[1].line).toBe(7);
+
+      expect(resultErrors[2].line).toBe(8);
+      expect(resultErrors[2].message).toBe("Use 'String#startsWith' method instead.");
+    } finally {
+      writeFileSync(filePath, content);
+    }
+  });
 });

tests/lib/rules-preprocessor/tsconfig.eslint.json

@@ -5,6 +5,7 @@
     "strictNullChecks": true
   },
   "include": [
-    "*"
-  ]
+    "**/*.ts",
+    "**/*.gts"
+  ],
 }