typescript-eslint · JoshuaKGoldberg · Oct 24, 2022 · Oct 7, 2022 · Oct 7, 2022 · Oct 7, 2022
diff --git a/docs/linting/TROUBLESHOOTING.md b/docs/linting/TROUBLESHOOTING.md
@@ -28,12 +28,48 @@ If you don't find an existing extension rule, or the extension rule doesn't work
 > We release a new version our tooling every week.
 > _Please_ ensure that you [check our the latest list of "extension" rules](https://typescript-eslint.io/rules/#extension-rules) **_before_** filing an issue.
 
-## I get errors telling me "The file must be included in at least one of the projects provided"
+## I get errors telling me "ESLint was configured to run ... However, that TSConfig does not / none of those TSConfigs include this file"
+
+### Fixing the Error
+
+- If you **do not** want to lint the file:
+  - Use [one of the options ESLint offers](https://eslint.org/docs/latest/user-guide/configuring/ignoring-code) to ignore files, namely a `.eslintignore` file, or `ignorePatterns` config.
+- If you **do** want to lint the file:
+  - If you **do not** want to lint the file with [type-aware linting](./TYPED_LINTING.md):
+    - Use [ESLint's `overrides` configuration](https://eslint.org/docs/latest/user-guide/configuring/configuration-files#configuration-based-on-glob-patterns) to configure the file to not be parsed with type information.
+      - A popular setup is to omit the above additions from top-level configuration and only apply them to TypeScript files via an override.
+      - Alternatively, you can add `parserOptions: { project: null }` to an override for the files you wish to exclude. Note that `{ project: undefined }` will not work.
+  - If you **do** want to lint the file with [type-aware linting](./TYPED_LINTING.md):
+    - Check the `include` option of each of the tsconfigs that you provide to `parserOptions.project` - you must ensure that all files match an `include` glob, or else our tooling will not be able to find it.
+    - If your file shouldn't be a part of one of your existing tsconfigs (for example, it is a script/tool local to the repo), then consider creating a new tsconfig (we advise calling it `tsconfig.eslint.json`) in your project root which lists this file in its `include`. For an example of this, you can check out the configuration we use in this repo:
+      - [`tsconfig.eslint.json`](https://github.com/typescript-eslint/typescript-eslint/blob/main/tsconfig.eslint.json)
+      - [`.eslintrc.js`](https://github.com/typescript-eslint/typescript-eslint/blob/main/.eslintrc.js)
+
+### More Details
+
+This error may appear from the combination of two things:
+
+- The ESLint configuration for the source file specifies at least one TSConfig file in `parserOptions.project`
+- None of those TSConfig files includes the source file being linted
+  - Note that files with the same name and different extension may not be recognized by TypeScript: see [`parserOptions.project` docs](https://github.com/typescript-eslint/typescript-eslint/tree/main/packages/parser#parseroptionsproject)
 
-This error means that the file that's being linted is not included in any of the TSConfig files you provided us.
-This happens when users have test files, config files, or similar that are not included.
+When TSConfig files are specified for parsing a source file, `@typescript-eslint/parser` will use the first TSConfig that is able to include that source file (per [aka.ms/tsconfig#include](https://www.typescriptlang.org/tsconfig#include)) to generate type information.
+However, if no specified TSConfig includes the source file, the parser won't be able to generate type information.
+
+This error most commonly happens on config files or similar that are not included in their project TSConfig(s).
+For example, many projects have files like:
+
+- An `.eslintrc.cjs` with `parserOptions.project: ["./tsconfig.json"]`
+- A `tsconfig.json` with `include: ["src"]`
+
+In that case, viewing the `.eslintrc.cjs` in an IDE with the ESLint extension will show the error notice that the file couldn't be linted because it isn't included in `tsconfig.json`.
+
+See our docs on [type aware linting](./TYPED_LINTING.md) for more information.
+
+## I get errors telling me "The file must be included in at least one of the projects provided"
 
-See our docs on [type aware linting](./TYPED_LINTING.md#i-get-errors-telling-me-the-file-must-be-included-in-at-least-one-of-the-projects-provided) for solutions.
+You're using an outdated version of `@typescript-eslint/parser`.
+Update to the latest version to see a more informative version of this error message, explained [above](#i-get-errors-telling-me-eslint-was-configured-to-run--however-that-tsconfig-does-not--none-of-those-tsconfigs-include-this-file).
 
 ## I use a framework (like Vue) that requires custom file extensions, and I get errors like "You should add `parserOptions.extraFileExtensions` to your config"
 

diff --git a/docs/linting/TYPED_LINTING.md b/docs/linting/TYPED_LINTING.md
@@ -52,23 +52,8 @@ This means that generally they usually only run a complete lint before a push, o
 
 ### I get errors telling me "The file must be included in at least one of the projects provided"
 
-This error means that the file that's being linted is not included in any of the tsconfig files you provided us.
-A lot of the time this happens when users have test files or similar that are not included in their normal tsconfigs.
-
-Depending on what you want to achieve:
-
-- If you **do not** want to lint the file:
-  - Use [one of the options ESLint offers](https://eslint.org/docs/user-guide/configuring#ignoring-files-and-directories) to ignore files, like a `.eslintignore` file, or `ignorePatterns` config.
-- If you **do** want to lint the file:
-  - If you **do not** want to lint the file with [type-aware linting](./TYPED_LINTING.md):
-    - Use [ESLint's `overrides` configuration](https://eslint.org/docs/user-guide/configuring#configuration-based-on-glob-patterns) to configure the file to not be parsed with type information.
-      - A popular setup is to omit the above additions from top-level configuration and only apply them to TypeScript files via an override.
-      - Alternatively, you can add `parserOptions: { project: null }` to an override for the files you wish to exclude. Note that `{ project: undefined }` will not work.
-  - If you **do** want to lint the file with [type-aware linting](./TYPED_LINTING.md):
-    - Check the `include` option of each of the tsconfigs that you provide to `parserOptions.project` - you must ensure that all files match an `include` glob, or else our tooling will not be able to find it.
-    - If your file shouldn't be a part of one of your existing tsconfigs (for example, it is a script/tool local to the repo), then consider creating a new tsconfig (we advise calling it `tsconfig.eslint.json`) in your project root which lists this file in its `include`. For an example of this, you can check out the configuration we use in this repo:
-      - [`tsconfig.eslint.json`](https://github.com/typescript-eslint/typescript-eslint/blob/main/tsconfig.eslint.json)
-      - [`.eslintrc.js`](https://github.com/typescript-eslint/typescript-eslint/blob/main/.eslintrc.js)
+You're using an outdated version of `@typescript-eslint/parser`.
+Update to the latest version to see a more informative version of this error message, explained [Troubleshooting and FAQs](./TROUBLESHOOTING.md##i-get-errors-telling-me-eslint-was-configured-to-run--however-that-tsconfig-does-not--none-of-those-tsconfigs-include-this-file).
 
 ## Troubleshooting
 

diff --git a/packages/typescript-estree/src/create-program/createProjectProgram.ts b/packages/typescript-estree/src/create-program/createProjectProgram.ts
@@ -34,65 +34,90 @@ function createProjectProgram(
 ): ASTAndProgram | undefined {
   log('Creating project program for: %s', extra.filePath);
 
-  const astAndProgram = firstDefined(
-    getProgramsForProjects(code, extra.filePath, extra),
-    currentProgram => getAstFromProgram(currentProgram, extra),
+  const programsForProjects = getProgramsForProjects(
+    code,
+    extra.filePath,
+    extra,
+  );
+  const astAndProgram = firstDefined(programsForProjects, currentProgram =>
+    getAstFromProgram(currentProgram, extra),
   );
 
-  if (!astAndProgram && !createDefaultProgram) {
-    // the file was either not matched within the tsconfig, or the extension wasn't expected
-    const errorLines = [
-      '"parserOptions.project" has been set for @typescript-eslint/parser.',
-      `The file does not match your project config: ${path.relative(
-        extra.tsconfigRootDir || process.cwd(),
-        extra.filePath,
-      )}.`,
-    ];
-    let hasMatchedAnError = false;
+  // The file was either matched within the tsconfig, or we allow creating a default program
+  if (astAndProgram || createDefaultProgram) {
+    return astAndProgram;
+  }
 
-    const extraFileExtensions = extra.extraFileExtensions || [];
+  const describeFilePath = (filePath: string): string => {
+    const relative = path.relative(
+      extra.tsconfigRootDir || process.cwd(),
+      filePath,
+    );
+    if (extra.tsconfigRootDir) {
+      return `<tsconfigRootDir>/${relative}`;
+    }
+    return `<cwd>/${relative}`;
+  };
 
-    extraFileExtensions.forEach(extraExtension => {
-      if (!extraExtension.startsWith('.')) {
-        errorLines.push(
-          `Found unexpected extension "${extraExtension}" specified with the "extraFileExtensions" option. Did you mean ".${extraExtension}"?`,
-        );
-      }
-      if (DEFAULT_EXTRA_FILE_EXTENSIONS.includes(extraExtension)) {
-        errorLines.push(
-          `You unnecessarily included the extension "${extraExtension}" with the "extraFileExtensions" option. This extension is already handled by the parser by default.`,
-        );
-      }
-    });
+  const describedFilePath = describeFilePath(extra.filePath);
+  const relativeProjects = extra.projects.map(describeFilePath);
+  const describedPrograms =
+    relativeProjects.length === 1
+      ? relativeProjects[0]
+      : `\n${relativeProjects.map(project => `- ${project}`).join('\n')}`;
+  const errorLines = [
+    `ESLint was configured to run on \`${describedFilePath}\` using \`parserOptions.project\`: ${describedPrograms}`,
+  ];
+  let hasMatchedAnError = false;
+
+  const extraFileExtensions = extra.extraFileExtensions || [];
 
-    const fileExtension = path.extname(extra.filePath);
-    if (!DEFAULT_EXTRA_FILE_EXTENSIONS.includes(fileExtension)) {
-      const nonStandardExt = `The extension for the file (${fileExtension}) is non-standard`;
-      if (extraFileExtensions.length > 0) {
-        if (!extraFileExtensions.includes(fileExtension)) {
-          errorLines.push(
-            `${nonStandardExt}. It should be added to your existing "parserOptions.extraFileExtensions".`,
-          );
-          hasMatchedAnError = true;
-        }
-      } else {
+  extraFileExtensions.forEach(extraExtension => {
+    if (!extraExtension.startsWith('.')) {
+      errorLines.push(
+        `Found unexpected extension \`${extraExtension}\` specified with the \`parserOptions.extraFileExtensions\` option. Did you mean \`.${extraExtension}\`?`,
+      );
+    }
+    if (DEFAULT_EXTRA_FILE_EXTENSIONS.includes(extraExtension)) {
+      errorLines.push(
+        `You unnecessarily included the extension \`${extraExtension}\` with the \`parserOptions.extraFileExtensions\` option. This extension is already handled by the parser by default.`,
+      );
+    }
+  });
+
+  const fileExtension = path.extname(extra.filePath);
+  if (!DEFAULT_EXTRA_FILE_EXTENSIONS.includes(fileExtension)) {
+    const nonStandardExt = `The extension for the file (\`${fileExtension}\`) is non-standard`;
+    if (extraFileExtensions.length > 0) {
+      if (!extraFileExtensions.includes(fileExtension)) {
         errorLines.push(
-          `${nonStandardExt}. You should add "parserOptions.extraFileExtensions" to your config.`,
+          `${nonStandardExt}. It should be added to your existing \`parserOptions.extraFileExtensions\`.`,
         );
         hasMatchedAnError = true;
       }
-    }
-
-    if (!hasMatchedAnError) {
+    } else {
       errorLines.push(
-        'The file must be included in at least one of the projects provided.',
+        `${nonStandardExt}. You should add \`parserOptions.extraFileExtensions\` to your config.`,
       );
+      hasMatchedAnError = true;
     }
+  }
 
-    throw new Error(errorLines.join('\n'));
+  if (!hasMatchedAnError) {
+    const [describedInclusions, describedSpecifiers] =
+      extra.projects.length === 1
+        ? ['that TSConfig does not', 'that TSConfig']
+        : ['none of those TSConfigs', 'one of those TSConfigs'];
+    errorLines.push(
+      `However, ${describedInclusions} include this file. Either:`,
+      `- Change ESLint's list of included files to not include this file`,
+      `- Change ${describedSpecifiers} to include this file`,
+      `- Create a new TSConfig that includes this file and include it in your parserOptions.project`,
+      `See the TypeScript ESLint docs for more info: https://typescript-eslint.io/docs/linting/troubleshooting##i-get-errors-telling-me-eslint-was-configured-to-run--however-that-tsconfig-does-not--none-of-those-tsconfigs-include-this-file`,
+    );
   }
 
-  return astAndProgram;
+  throw new Error(errorLines.join('\n'));
 }
 
 export { createProjectProgram };
diff --git a/packages/typescript-estree/tests/fixtures/invalidFileErrors/tsconfig.extra.json b/packages/typescript-estree/tests/fixtures/invalidFileErrors/tsconfig.extra.json
@@ -0,0 +1 @@
+{}