Breaking: lint overrides files (fixes #10828, refs eslint/rfcs#20) (#…

…12677)

* Breaking: lint `overrides` files (fixes #10828, refs eslint/rfcs#20)

* update docs

* sort for tests

See also: #12700 (comment)

conf/default-cli-options.js

@@ -12,7 +12,7 @@ module.exports = {
     useEslintrc: true,
     envs: [],
     globals: [],
-    extensions: [".js"],
+    extensions: null,
     ignore: true,
     ignorePath: void 0,
     cache: false,

docs/user-guide/command-line-interface.md

@@ -127,19 +127,19 @@ Examples:
 
 #### `--ext`
 
-This option allows you to specify which file extensions ESLint will use when searching for JavaScript files in the directories you specify.
-By default, it uses `.js` as the only file extension.
+This option allows you to specify which file extensions ESLint will use when searching for target files in the directories you specify.
+By default, ESLint lints `*.js` files and the files that match the `overrides` entries of your configuration.
 
 Examples:
 
-    # Use only .js2 extension
-    eslint . --ext .js2
+    # Use only .ts extension
+    eslint . --ext .ts
 
-    # Use both .js and .js2
-    eslint . --ext .js --ext .js2
+    # Use both .js and .ts
+    eslint . --ext .js --ext .ts
 
-    # Also use both .js and .js2
-    eslint . --ext .js,.js2
+    # Also use both .js and .ts
+    eslint . --ext .js,.ts
 
 **Note:** `--ext` is only used when the arguments are directories. If you use glob patterns or file names, then `--ext` is ignored.
 

docs/user-guide/configuring.md

@@ -125,7 +125,7 @@ Processors may make named code blocks such as `0.js` and `1.js`. ESLint handles
 }
 ```
 
-ESLint checks the file extension of named code blocks then ignores those if [`--ext` CLI option](../user-guide/command-line-interface.md#--ext) didn't include the file extension. Be sure to specify the `--ext` option if you wanted to lint named code blocks other than `*.js`.
+ESLint checks the file path of named code blocks then ignores those if any `overrides` entry didn't match the file path. Be sure to make `overrides` entry if you wanted to lint named code blocks other than `*.js`.
 
 ## Specifying Environments
 
@@ -990,6 +990,12 @@ In your `.eslintrc.json`:
 }
 ```
 
+### Specifying Target Files to Lint
+
+If you specified directories with CLI (e.g., `eslint lib`), ESLint searches target files in the directory to lint. The target files are `*.js` or the files that match any of `overrides` entries (but exclude entries that are any of `files` end with `*`).
+
+If you specified the [`--ext`](./command-line-interface#ext) command line option along with directories, the target files are only the files that have specified file extensions regardless of `overrides` entries.
+
 ## Comments in Configuration Files
 
 Both the JSON and YAML configuration file formats support comments (`package.json` files should not include them). You can use JavaScript-style comments or YAML-style comments in either type of file and ESLint will safely ignore them. This allows your configuration files to be more human-friendly. For example:
@@ -1007,10 +1013,6 @@ Both the JSON and YAML configuration file formats support comments (`package.jso
 }
 ```
 
-## Specifying File extensions to Lint
-
-Currently the sole method for telling ESLint which file extensions to lint is by specifying a comma separated list of extensions using the [`--ext`](./command-line-interface#ext) command line option. Note this flag only takes effect in conjunction with directories, and will be ignored if used with filenames or glob patterns.
-
 ## Ignoring Files and Directories
 
 ### `ignorePatterns` in config files

lib/cli-engine/cascading-config-array-factory.js

@@ -106,6 +106,7 @@ function createBaseConfigArray({
      */
     if (rulePaths && rulePaths.length > 0) {
         baseConfigArray.push({
+            type: "config",
             name: "--rulesdir",
             filePath: "",
             plugins: {

lib/cli-engine/cli-engine.js

@@ -57,7 +57,7 @@ const validFixTypes = new Set(["problem", "suggestion", "layout"]);
  * @property {string} configFile The configuration file to use.
  * @property {string} cwd The value to use for the current working directory.
  * @property {string[]} envs An array of environments to load.
- * @property {string[]} extensions An array of file extensions to check.
+ * @property {string[]|null} extensions An array of file extensions to check.
  * @property {boolean|Function} fix Execute in autofix mode. If a function, should return a boolean.
  * @property {string[]} fixTypes Array of rule types to apply fixes for.
  * @property {string[]} globals An array of global variables to declare.
@@ -201,7 +201,7 @@ function calculateStatsPerRun(results) {
  * @param {boolean} config.fix If `true` then it does fix.
  * @param {boolean} config.allowInlineConfig If `true` then it uses directive comments.
  * @param {boolean} config.reportUnusedDisableDirectives If `true` then it reports unused `eslint-disable` comments.
- * @param {RegExp} config.extensionRegExp The `RegExp` object that tests if a file path has the allowed file extensions.
+ * @param {FileEnumerator} config.fileEnumerator The file enumerator to check if a path is a target or not.
  * @param {Linter} config.linter The linter instance to verify.
  * @returns {LintResult} The result of linting.
  * @private
@@ -214,7 +214,7 @@ function verifyText({
     fix,
     allowInlineConfig,
     reportUnusedDisableDirectives,
-    extensionRegExp,
+    fileEnumerator,
     linter
 }) {
     const filePath = providedFilePath || "<text>";
@@ -238,13 +238,11 @@ function verifyText({
 
             /**
              * Check if the linter should adopt a given code block or not.
-             * Currently, the linter adopts code blocks if the name matches `--ext` option.
-             * In the future, `overrides` in the configuration would affect the adoption (https://github.com/eslint/rfcs/pull/20).
              * @param {string} blockFilename The virtual filename of a code block.
              * @returns {boolean} `true` if the linter should adopt the code block.
              */
             filterCodeBlock(blockFilename) {
-                return extensionRegExp.test(blockFilename);
+                return fileEnumerator.isTargetPath(blockFilename);
             }
         }
     );
@@ -704,7 +702,7 @@ class CLIEngine {
             return patterns.filter(Boolean);
         }
 
-        const extensions = options.extensions.map(ext => ext.replace(/^\./u, ""));
+        const extensions = (options.extensions || [".js"]).map(ext => ext.replace(/^\./u, ""));
         const dirSuffix = `/**/*.{${extensions.join(",")}}`;
 
         return patterns.filter(Boolean).map(pathname => {
@@ -803,7 +801,7 @@ class CLIEngine {
                 fix,
                 allowInlineConfig,
                 reportUnusedDisableDirectives,
-                extensionRegExp: fileEnumerator.extensionRegExp,
+                fileEnumerator,
                 linter
             });
 
@@ -891,7 +889,7 @@ class CLIEngine {
                 fix,
                 allowInlineConfig,
                 reportUnusedDisableDirectives,
-                extensionRegExp: fileEnumerator.extensionRegExp,
+                fileEnumerator,
                 linter
             }));
         }

lib/cli-engine/config-array-factory.js

@@ -565,7 +565,7 @@ class ConfigArrayFactory {
      */
     *_normalizeESLintIgnoreData(ignorePatterns, filePath, name) {
         const elements = this._normalizeObjectConfigData(
-            { ignorePatterns },
+            { type: "ignore", ignorePatterns },
             filePath,
             name
         );
@@ -667,6 +667,7 @@ class ConfigArrayFactory {
             root,
             rules,
             settings,
+            type = "config",
             overrides: overrideList = []
         },
         filePath,
@@ -698,6 +699,7 @@ class ConfigArrayFactory {
         yield {
 
             // Debug information.
+            type,
             name,
             filePath,
 
@@ -1047,6 +1049,7 @@ class ConfigArrayFactory {
                 if (processorId.startsWith(".")) {
                     yield* this._normalizeObjectConfigData(
                         {
+                            type: "implicit-processor",
                             files: [`*${processorId}`],
                             processor: `${pluginId}/${processorId}`
                         },

lib/cli-engine/config-array/config-array.js

@@ -454,6 +454,25 @@ class ConfigArray extends Array {
 
         return cache.get(cacheKey);
     }
+
+    /**
+     * Check if a given path is an additional lint target.
+     * @param {string} filePath The absolute path to the target file.
+     * @returns {boolean} `true` if the file is an additional lint target.
+     */
+    isAdditionalTargetPath(filePath) {
+        for (const { criteria, type } of this) {
+            if (
+                type === "config" &&
+                criteria &&
+                !criteria.endsWithWildcard &&
+                criteria.test(filePath)
+            ) {
+                return true;
+            }
+        }
+        return false;
+    }
 }
 
 const exportObject = {

lib/cli-engine/config-array/override-tester.js

@@ -96,14 +96,22 @@ class OverrideTester {
     static create(files, excludedFiles, basePath) {
         const includePatterns = normalizePatterns(files);
         const excludePatterns = normalizePatterns(excludedFiles);
-        const allPatterns = includePatterns.concat(excludePatterns);
+        let endsWithWildcard = false;
 
-        if (allPatterns.length === 0) {
+        if (includePatterns.length === 0) {
             return null;
         }
 
         // Rejects absolute paths or relative paths to parents.
-        for (const pattern of allPatterns) {
+        for (const pattern of includePatterns) {
+            if (path.isAbsolute(pattern) || pattern.includes("..")) {
+                throw new Error(`Invalid override pattern (expected relative path not containing '..'): ${pattern}`);
+            }
+            if (pattern.endsWith("*")) {
+                endsWithWildcard = true;
+            }
+        }
+        for (const pattern of excludePatterns) {
             if (path.isAbsolute(pattern) || pattern.includes("..")) {
                 throw new Error(`Invalid override pattern (expected relative path not containing '..'): ${pattern}`);
             }
@@ -112,7 +120,11 @@ class OverrideTester {
         const includes = toMatcher(includePatterns);
         const excludes = toMatcher(excludePatterns);
 
-        return new OverrideTester([{ includes, excludes }], basePath);
+        return new OverrideTester(
+            [{ includes, excludes }],
+            basePath,
+            endsWithWildcard
+        );
     }
 
     /**
@@ -125,28 +137,44 @@ class OverrideTester {
      */
     static and(a, b) {
         if (!b) {
-            return a && new OverrideTester(a.patterns, a.basePath);
+            return a && new OverrideTester(
+                a.patterns,
+                a.basePath,
+                a.endsWithWildcard
+            );
         }
         if (!a) {
-            return new OverrideTester(b.patterns, b.basePath);
+            return new OverrideTester(
+                b.patterns,
+                b.basePath,
+                b.endsWithWildcard
+            );
         }
 
         assert.strictEqual(a.basePath, b.basePath);
-        return new OverrideTester(a.patterns.concat(b.patterns), a.basePath);
+        return new OverrideTester(
+            a.patterns.concat(b.patterns),
+            a.basePath,
+            a.endsWithWildcard || b.endsWithWildcard
+        );
     }
 
     /**
      * Initialize this instance.
      * @param {Pattern[]} patterns The matchers.
      * @param {string} basePath The base path.
+     * @param {boolean} endsWithWildcard If `true` then a pattern ends with `*`.
      */
-    constructor(patterns, basePath) {
+    constructor(patterns, basePath, endsWithWildcard = false) {
 
         /** @type {Pattern[]} */
         this.patterns = patterns;
 
         /** @type {string} */
         this.basePath = basePath;
+
+        /** @type {boolean} */
+        this.endsWithWildcard = endsWithWildcard;
     }
 
     /**