feat(eslint-plugin): add extension rule no-loss-of-precision (typescript-eslint#2196)

yeonjuan · bradzacher · web-flow · commit 535b0f2ddd82 · 2020-06-15T19:21:38.000-07:00
Co-authored-by: Brad Zacher &lt;brad.zacher@gmail.com&gt;
diff --git a/package.json b/package.json
@@ -76,7 +76,7 @@
     "cspell": "^4.0.61",
     "cz-conventional-changelog": "^3.2.0",
     "downlevel-dts": "^0.4.0",
-    "eslint": "^7.0.0",
+    "eslint": "^7.2.0",
     "eslint-plugin-eslint-comments": "^3.1.2",
     "eslint-plugin-eslint-plugin": "^2.2.1",
     "eslint-plugin-import": "^2.20.2",
diff --git a/packages/eslint-plugin/README.md b/packages/eslint-plugin/README.md
@@ -191,6 +191,7 @@ In these cases, we create what we call an extension rule; a rule within our plug
 | [`@typescript-eslint/no-extra-parens`](./docs/rules/no-extra-parens.md)                         | Disallow unnecessary parentheses                                               |                    | :wrench: |                   |
 | [`@typescript-eslint/no-extra-semi`](./docs/rules/no-extra-semi.md)                             | Disallow unnecessary semicolons                                                | :heavy_check_mark: | :wrench: |                   |
 | [`@typescript-eslint/no-invalid-this`](./docs/rules/no-invalid-this.md)                         | disallow `this` keywords outside of classes or class-like objects              |                    |          |                   |
+| [`@typescript-eslint/no-loss-of-precision`](./docs/rules/no-loss-of-precision.md)               | Disallow literal numbers that lose precision                                   |                    |          |                   |
 | [`@typescript-eslint/no-magic-numbers`](./docs/rules/no-magic-numbers.md)                       | Disallow magic numbers                                                         |                    |          |                   |
 | [`@typescript-eslint/no-unused-expressions`](./docs/rules/no-unused-expressions.md)             | Disallow unused expressions                                                    |                    |          |                   |
 | [`@typescript-eslint/no-unused-vars`](./docs/rules/no-unused-vars.md)                           | Disallow unused variables                                                      | :heavy_check_mark: |          |                   |
diff --git a/packages/eslint-plugin/docs/rules/no-loss-of-precision.md b/packages/eslint-plugin/docs/rules/no-loss-of-precision.md
@@ -0,0 +1,19 @@
+# Disallow literal numbers that lose precision (`no-loss-of-precision`)
+
+## Rule Details
+
+This rule extends the base [`eslint/no-loss-of-precision`](https://eslint.org/docs/rules/no-loss-of-precision) rule.
+It adds support for [numeric separators](https://github.com/tc39/proposal-numeric-separator).
+Note that this rule requires ESLint v7.
+
+## How to use
+
+```jsonc
+{
+  // note you must disable the base rule as it can report incorrect errors
+  "no-loss-of-precision": "off",
+  "@typescript-eslint/no-loss-of-precision": ["error"]
+}
+```
+
+<sup>Taken with ❤️ [from ESLint core](https://github.com/eslint/eslint/blob/master/docs/rules/no-loss-of-precision.md)</sup>
diff --git a/packages/eslint-plugin/src/configs/all.ts b/packages/eslint-plugin/src/configs/all.ts
@@ -59,6 +59,8 @@ export = {
     'no-invalid-this': 'off',
     '@typescript-eslint/no-invalid-this': 'error',
     '@typescript-eslint/no-invalid-void-type': 'error',
+    'no-loss-of-precision': 'off',
+    '@typescript-eslint/no-loss-of-precision': 'error',
     'no-magic-numbers': 'off',
     '@typescript-eslint/no-magic-numbers': 'error',
     '@typescript-eslint/no-misused-new': 'error',
diff --git a/packages/eslint-plugin/src/rules/index.ts b/packages/eslint-plugin/src/rules/index.ts
@@ -96,6 +96,7 @@ import typedef from './typedef';
 import unboundMethod from './unbound-method';
 import unifiedSignatures from './unified-signatures';
 import linesBetweenClassMembers from './lines-between-class-members';
+import noLossOfPrecision from './no-loss-of-precision';
 
 export default {
   'adjacent-overload-signatures': adjacentOverloadSignatures,
@@ -196,4 +197,5 @@ export default {
   'unbound-method': unboundMethod,
   'unified-signatures': unifiedSignatures,
   'lines-between-class-members': linesBetweenClassMembers,
+  'no-loss-of-precision': noLossOfPrecision,
 };
diff --git a/packages/eslint-plugin/src/rules/no-loss-of-precision.ts b/packages/eslint-plugin/src/rules/no-loss-of-precision.ts
@@ -0,0 +1,53 @@
+import { TSESTree } from '@typescript-eslint/experimental-utils';
+import BaseRule from 'eslint/lib/rules/no-loss-of-precision';
+import * as util from '../util';
+
+const baseRule = ((): typeof BaseRule | null => {
+  try {
+    return require('eslint/lib/rules/no-loss-of-precision');
+  } catch {
+    /* istanbul ignore next */
+    return null;
+  }
+})();
+
+type Options = util.InferOptionsTypeFromRule<typeof BaseRule>;
+type MessageIds = util.InferMessageIdsTypeFromRule<typeof BaseRule>;
+
+export default util.createRule<Options, MessageIds>({
+  name: 'no-loss-of-precision',
+  meta: {
+    type: 'problem',
+    docs: {
+      description: 'Disallow literal numbers that lose precision',
+      category: 'Possible Errors',
+      recommended: false,
+      extendsBaseRule: true,
+    },
+    schema: [],
+    messages: baseRule?.meta.messages ?? { noLossOfPrecision: '' },
+  },
+  defaultOptions: [],
+  create(context) {
+    /* istanbul ignore if */ if (baseRule === null) {
+      throw new Error(
+        '@typescript-eslint/no-loss-of-precision requires at least ESLint v7.1.0',
+      );
+    }
+
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-type-assertion
+    const rules = baseRule!.create(context);
+
+    function isSeperatedNumeric(node: TSESTree.Literal): boolean {
+      return typeof node.value === 'number' && node.raw.includes('_');
+    }
+    return {
+      Literal(node: TSESTree.Literal): void {
+        rules.Literal({
+          ...node,
+          raw: isSeperatedNumeric(node) ? node.raw.replace(/_/g, '') : node.raw,
+        });
+      },
+    };
+  },
+});
diff --git a/packages/eslint-plugin/tests/rules/no-loss-of-precision.test.ts b/packages/eslint-plugin/tests/rules/no-loss-of-precision.test.ts
@@ -0,0 +1,36 @@
+import rule from '../../src/rules/no-loss-of-precision';
+import { RuleTester } from '../RuleTester';
+
+const ruleTester = new RuleTester({
+  parser: '@typescript-eslint/parser',
+});
+
+ruleTester.run('no-loss-of-precision', rule, {
+  valid: [
+    'const x = 12345;',
+    'const x = 123.456;',
+    'const x = -123.456;',
+    'const x = 123_456;',
+    'const x = 123_00_000_000_000_000_000_000_000;',
+    'const x = 123.000_000_000_000_000_000_000_0;',
+  ],
+  invalid: [
+    {
+      code: 'const x = 9007199254740993;',
+      errors: [{ messageId: 'noLossOfPrecision' }],
+    },
+    {
+      code: 'const x = 9_007_199_254_740_993;',
+      errors: [{ messageId: 'noLossOfPrecision' }],
+    },
+    {
+      code: 'const x = 9_007_199_254_740.993e3;',
+      errors: [{ messageId: 'noLossOfPrecision' }],
+    },
+    {
+      code:
+        'const x = 0b100_000_000_000_000_000_000_000_000_000_000_000_000_000_000_000_000_001;',
+      errors: [{ messageId: 'noLossOfPrecision' }],
+    },
+  ],
+});
diff --git a/packages/eslint-plugin/typings/eslint-rules.d.ts b/packages/eslint-plugin/typings/eslint-rules.d.ts
@@ -702,3 +702,16 @@ declare module 'eslint/lib/rules/dot-notation' {
   >;
   export = rule;
 }
+
+declare module 'eslint/lib/rules/no-loss-of-precision' {
+  import { TSESLint, TSESTree } from '@typescript-eslint/experimental-utils';
+
+  const rule: TSESLint.RuleModule<
+    'noLossOfPrecision',
+    [],
+    {
+      Literal(node: TSESTree.Literal): void;
+    }
+  >;
+  export = rule;
+}
diff --git a/yarn.lock b/yarn.lock
@@ -1750,7 +1750,7 @@ acorn@^6.0.1:
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.1.tgz#531e58ba3f51b9dacb9a6646ca4debf5b14ca474"
   integrity sha512-ZVA9k326Nwrj3Cj9jlh3wGFutC2ZornPNARZwsNYqQYgN0EsV2d53w5RN/co65Ohn4sUAUtb1rSUAOD6XN9idA==
 
-acorn@^7.1.0, acorn@^7.1.1:
+acorn@^7.1.0, acorn@^7.2.0:
   version "7.2.0"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-7.2.0.tgz#17ea7e40d7c8640ff54a694c889c26f31704effe"
   integrity sha512-apwXVmYVpQ34m/i71vrApRrRKCWQnZZF1+npOD0WV5xZFfwWOmKGQ2RWlfdy9vWITsenisM8M0Qeq8agcFHNiQ==
@@ -3614,6 +3614,14 @@ eslint-scope@^5.0.0:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
+eslint-scope@^5.1.0:
+  version "5.1.0"
+  resolved "https://registry.yarnpkg.com/eslint-scope/-/eslint-scope-5.1.0.tgz#d0f971dfe59c69e0cada684b23d49dbf82600ce5"
+  integrity sha512-iiGRvtxWqgtx5m8EyQUJihBloE4EnYeGE/bz1wSPwJE6tZuJUtHlhqDM4Xj2ukE8Dyy1+HCZ4hE0fzIVMzb58w==
+  dependencies:
+    esrecurse "^4.1.0"
+    estraverse "^4.1.1"
+
 eslint-utils@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/eslint-utils/-/eslint-utils-2.0.0.tgz#7be1cc70f27a72a76cd14aa698bcabed6890e1cd"
@@ -3626,21 +3634,26 @@ eslint-visitor-keys@^1.1.0:
   resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.1.0.tgz#e2a82cea84ff246ad6fb57f9bde5b46621459ec2"
   integrity sha512-8y9YjtM1JBJU/A9Kc+SbaOV4y29sSWckBwMHa+FGtVj5gN/sbnKDf6xJUl+8g7FAij9LVaP8C24DUiH/f/2Z9A==
 
-eslint@^7.0.0:
-  version "7.0.0"
-  resolved "https://registry.yarnpkg.com/eslint/-/eslint-7.0.0.tgz#c35dfd04a4372110bd78c69a8d79864273919a08"
-  integrity sha512-qY1cwdOxMONHJfGqw52UOpZDeqXy8xmD0u8CT6jIstil72jkhURC704W8CFyTPDPllz4z4lu0Ql1+07PG/XdIg==
+eslint-visitor-keys@^1.2.0:
+  version "1.2.0"
+  resolved "https://registry.yarnpkg.com/eslint-visitor-keys/-/eslint-visitor-keys-1.2.0.tgz#74415ac884874495f78ec2a97349525344c981fa"
+  integrity sha512-WFb4ihckKil6hu3Dp798xdzSfddwKKU3+nGniKF6HfeW6OLd2OUDEPP7TcHtB5+QXOKg2s6B2DaMPE1Nn/kxKQ==
+
+eslint@^7.2.0:
+  version "7.2.0"
+  resolved "https://registry.yarnpkg.com/eslint/-/eslint-7.2.0.tgz#d41b2e47804b30dbabb093a967fb283d560082e6"
+  integrity sha512-B3BtEyaDKC5MlfDa2Ha8/D6DsS4fju95zs0hjS3HdGazw+LNayai38A25qMppK37wWGWNYSPOR6oYzlz5MHsRQ==
   dependencies:
     "@babel/code-frame" "^7.0.0"
     ajv "^6.10.0"
     chalk "^4.0.0"
     cross-spawn "^7.0.2"
     debug "^4.0.1"
     doctrine "^3.0.0"
-    eslint-scope "^5.0.0"
+    eslint-scope "^5.1.0"
     eslint-utils "^2.0.0"
-    eslint-visitor-keys "^1.1.0"
-    espree "^7.0.0"
+    eslint-visitor-keys "^1.2.0"
+    espree "^7.1.0"
     esquery "^1.2.0"
     esutils "^2.0.2"
     file-entry-cache "^5.0.1"
@@ -3668,14 +3681,14 @@ eslint@^7.0.0:
     text-table "^0.2.0"
     v8-compile-cache "^2.0.3"
 
-espree@^7.0.0:
-  version "7.0.0"
-  resolved "https://registry.yarnpkg.com/espree/-/espree-7.0.0.tgz#8a7a60f218e69f120a842dc24c5a88aa7748a74e"
-  integrity sha512-/r2XEx5Mw4pgKdyb7GNLQNsu++asx/dltf/CI8RFi9oGHxmQFgvLbc5Op4U6i8Oaj+kdslhJtVlEZeAqH5qOTw==
+espree@^7.1.0:
+  version "7.1.0"
+  resolved "https://registry.yarnpkg.com/espree/-/espree-7.1.0.tgz#a9c7f18a752056735bf1ba14cb1b70adc3a5ce1c"
+  integrity sha512-dcorZSyfmm4WTuTnE5Y7MEN1DyoPYy1ZR783QW1FJoenn7RailyWFsq/UL6ZAAA7uXurN9FIpYyUs3OfiIW+Qw==
   dependencies:
-    acorn "^7.1.1"
+    acorn "^7.2.0"
     acorn-jsx "^5.2.0"
-    eslint-visitor-keys "^1.1.0"
+    eslint-visitor-keys "^1.2.0"
 
 esprima@^2.7.0:
   version "2.7.3"
