fix(eslint-plugin): [ban-ts-comment] support block comments (#2644)

packages/eslint-plugin/README.md

@@ -100,7 +100,7 @@ Pro Tip: For larger codebases you may want to consider splitting our linting int
 | [`@typescript-eslint/adjacent-overload-signatures`](./docs/rules/adjacent-overload-signatures.md)                     | Require that member overloads be consecutive                                                                            | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/array-type`](./docs/rules/array-type.md)                                                         | Requires using either `T[]` or `Array<T>` for arrays                                                                    |                    | :wrench: |                   |
 | [`@typescript-eslint/await-thenable`](./docs/rules/await-thenable.md)                                                 | Disallows awaiting a value that is not a Thenable                                                                       | :heavy_check_mark: |          | :thought_balloon: |
-| [`@typescript-eslint/ban-ts-comment`](./docs/rules/ban-ts-comment.md)                                                 | Bans `// @ts-<directive>` comments from being used or requires descriptions after directive                             | :heavy_check_mark: |          |                   |
+| [`@typescript-eslint/ban-ts-comment`](./docs/rules/ban-ts-comment.md)                                                 | Bans `@ts-<directive>` comments from being used or requires descriptions after directive                                | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/ban-tslint-comment`](./docs/rules/ban-tslint-comment.md)                                         | Bans `// tslint:<rule-flag>` comments from being used                                                                   |                    | :wrench: |                   |
 | [`@typescript-eslint/ban-types`](./docs/rules/ban-types.md)                                                           | Bans specific types from being used                                                                                     | :heavy_check_mark: | :wrench: |                   |
 | [`@typescript-eslint/class-literal-property-style`](./docs/rules/class-literal-property-style.md)                     | Ensures that literals on classes are exposed in a consistent style                                                      |                    | :wrench: |                   |

packages/eslint-plugin/docs/rules/ban-ts-comment.md

@@ -1,4 +1,4 @@
-# Bans `// @ts-<directive>` comments from being used or requires descriptions after directive (`ban-ts-comment`)
+# Bans `@ts-<directive>` comments from being used or requires descriptions after directive (`ban-ts-comment`)
 
 TypeScript provides several directive comments that can be used to alter how it processes files.
 Using these to suppress TypeScript Compiler Errors reduces the effectiveness of TypeScript overall.
@@ -41,13 +41,19 @@ const defaultOptions: Options = {
 
 A value of `true` for a particular directive means that this rule will report if it finds any usage of said directive.
 
-For example, with the defaults above the following patterns are considered warnings:
+For example, with the defaults above the following patterns are considered warnings for single line or comment block lines:
 
 ```ts
 if (false) {
   // @ts-ignore: Unreachable code error
   console.log('hello');
 }
+if (false) {
+  /*
+  @ts-ignore: Unreachable code error
+  */
+  console.log('hello');
+}
 ```
 
 The following patterns are not warnings:
@@ -63,22 +69,32 @@ if (false) {
 
 A value of `'allow-with-description'` for a particular directive means that this rule will report if it finds a directive that does not have a description following the directive (on the same line).
 
-For example, with `{ 'ts-expect-error': 'allow-with-description' }` the following pattern is considered a warning:
+For example, with `{ 'ts-expect-error': 'allow-with-description' }` the following patterns are considered a warning:
 
 ```ts
 if (false) {
   // @ts-expect-error
   console.log('hello');
 }
+if (false) {
+  /* @ts-expect-error */
+  console.log('hello');
+}
 ```
 
-The following pattern is not a warning:
+The following patterns are not a warning:
 
 ```ts
 if (false) {
   // @ts-expect-error: Unreachable code error
   console.log('hello');
 }
+if (false) {
+  /*
+  @ts-expect-error: Unreachable code error
+  */
+  console.log('hello');
+}
 ```
 
 ### `minimumDescriptionLength`

packages/eslint-plugin/src/rules/ban-ts-comment.ts

@@ -21,15 +21,15 @@ export default util.createRule<[Options], MessageIds>({
     type: 'problem',
     docs: {
       description:
-        'Bans `// @ts-<directive>` comments from being used or requires descriptions after directive',
+        'Bans `@ts-<directive>` comments from being used or requires descriptions after directive',
       category: 'Best Practices',
       recommended: 'error',
     },
     messages: {
       tsDirectiveComment:
-        'Do not use "// @ts-{{directive}}" because it alters compilation errors.',
+        'Do not use "@ts-{{directive}}" because it alters compilation errors.',
       tsDirectiveCommentRequiresDescription:
-        'Include a description after the "// @ts-{{directive}}" directive to explain why the @ts-{{directive}} is necessary. The description must be {{minimumDescriptionLength}} characters or longer.',
+        'Include a description after the "@ts-{{directive}}" directive to explain why the @ts-{{directive}} is necessary. The description must be {{minimumDescriptionLength}} characters or longer.',
     },
     schema: [
       {
@@ -98,20 +98,25 @@ export default util.createRule<[Options], MessageIds>({
     },
   ],
   create(context, [options]) {
-    const tsCommentRegExp = /^\/*\s*@ts-(expect-error|ignore|check|nocheck)(.*)/;
+    /*
+      The regex used are taken from the ones used in the official TypeScript repo -
+      https://github.com/microsoft/TypeScript/blob/master/src/compiler/scanner.ts#L281-L289
+    */
+    const commentDirectiveRegExSingleLine = /^\/*\s*@ts-(expect-error|ignore|check|nocheck)(.*)/;
+    const commentDirectiveRegExMultiLine = /^\s*(?:\/|\*)*\s*@ts-(expect-error|ignore|check|nocheck)(.*)/;
     const sourceCode = context.getSourceCode();
 
     return {
       Program(): void {
         const comments = sourceCode.getAllComments();
 
         comments.forEach(comment => {
+          let regExp = commentDirectiveRegExSingleLine;
+
           if (comment.type !== AST_TOKEN_TYPES.Line) {
-            return;
+            regExp = commentDirectiveRegExMultiLine;
           }
-
-          const [, directive, description] =
-            tsCommentRegExp.exec(comment.value) ?? [];
+          const [, directive, description] = regExp.exec(comment.value) ?? [];
 
           const fullDirective = `ts-${directive}` as keyof Options;