From 19c600a3dd485669cb87ae8f81b010e65eee1df8 Mon Sep 17 00:00:00 2001
From: Leon Si <vcjwt@leonzalion.com>
Date: Fri, 8 Apr 2022 17:14:44 -0400
Subject: [PATCH] feat(eslint-plugin): add support for valid number and bigint
 intersections in restrict-plus-operands rule (#4795)

* feat: support number and bigint intersections in restrict-plus-operands rule

* fix: tests

* style: formatting
---
 .../src/rules/restrict-plus-operands.ts       |  15 +-
 .../rules/restrict-plus-operands.test.ts      | 222 ++++++++++++++++++
 2 files changed, 236 insertions(+), 1 deletion(-)

diff --git a/packages/eslint-plugin/src/rules/restrict-plus-operands.ts b/packages/eslint-plugin/src/rules/restrict-plus-operands.ts
index d126dc42bfb..6d2052b6be7 100644
--- a/packages/eslint-plugin/src/rules/restrict-plus-operands.ts
+++ b/packages/eslint-plugin/src/rules/restrict-plus-operands.ts
@@ -88,7 +88,20 @@ export default util.createRule<Options, MessageIds>({
 
       if (type.isIntersection()) {
         const types = type.types.map(getBaseTypeOfLiteralType);
-        return types.some(value => value === 'string') ? 'string' : 'invalid';
+
+        if (types.some(value => value === 'string')) {
+          return 'string';
+        }
+
+        if (types.some(value => value === 'number')) {
+          return 'number';
+        }
+
+        if (types.some(value => value === 'bigint')) {
+          return 'bigint';
+        }
+
+        return 'invalid';
       }
 
       const stringType = typeChecker.typeToString(type);
diff --git a/packages/eslint-plugin/tests/rules/restrict-plus-operands.test.ts b/packages/eslint-plugin/tests/rules/restrict-plus-operands.test.ts
index ec14f26db7b..72621ad0efa 100644
--- a/packages/eslint-plugin/tests/rules/restrict-plus-operands.test.ts
+++ b/packages/eslint-plugin/tests/rules/restrict-plus-operands.test.ts
@@ -109,6 +109,46 @@ const x = a + b;
     `
 declare const a: 'string literal' & string;
 declare const b: string;
+const x = a + b;
+    `,
+    `
+declare const a: {} & number;
+declare const b: number;
+const x = a + b;
+    `,
+    `
+declare const a: unknown & number;
+declare const b: number;
+const x = a + b;
+    `,
+    `
+declare const a: number & number;
+declare const b: number;
+const x = a + b;
+    `,
+    `
+declare const a: 42 & number;
+declare const b: number;
+const x = a + b;
+    `,
+    `
+declare const a: {} & bigint;
+declare const b: bigint;
+const x = a + b;
+    `,
+    `
+declare const a: unknown & bigint;
+declare const b: bigint;
+const x = a + b;
+    `,
+    `
+declare const a: bigint & bigint;
+declare const b: bigint;
+const x = a + b;
+    `,
+    `
+declare const a: 42n & bigint;
+declare const b: bigint;
 const x = a + b;
     `,
     `
@@ -575,6 +615,188 @@ function foo<T extends 1>(a: T) {
         },
       ],
     },
+    {
+      code: `
+        declare const a: boolean & number;
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notNumbers',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: symbol & number;
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notNumbers',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: object & number;
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notNumbers',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: never & number;
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notNumbers',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: any & number;
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notValidAnys',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: { a: 1 } & { b: 2 };
+        declare const b: number;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notNumbers',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: boolean & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: number & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: symbol & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: object & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: never & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: any & bigint;
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notValidAnys',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
+    {
+      code: `
+        declare const a: { a: 1 } & { b: 2 };
+        declare const b: bigint;
+        const x = a + b;
+      `,
+      errors: [
+        {
+          messageId: 'notBigInts',
+          line: 4,
+          column: 19,
+        },
+      ],
+    },
     {
       code: `
 let foo: string | undefined;