feat(eslint-plugin): [restrict-template-expressions] add option to allow RegExp

packages/eslint-plugin/docs/rules/restrict-template-expressions.md

@@ -35,13 +35,16 @@ type Options = {
   allowAny?: boolean;
   // if true, also allow null and undefined in template expressions
   allowNullish?: boolean;
+  // if true, also allow RegExp in template expressions
+  allowRegExp?: boolean;
 };
 
 const defaults = {
   allowNumber: true,
   allowBoolean: false,
   allowAny: false,
   allowNullish: false,
+  allowRegExp: false,
 };
 ```
 
@@ -83,3 +86,17 @@ Examples of additional **correct** code for this rule with `{ allowNullish: true
 const arg = condition ? 'ok' : null;
 const msg1 = `arg = ${arg}`;
 ```
+
+### `allowRegExp`
+
+Examples of additional **correct** code for this rule with `{ allowRegExp: true }`:
+
+```ts
+const arg = new RegExp('foo');
+const msg1 = `arg = ${arg}`;
+```
+
+```ts
+const arg = /foo/;
+const msg1 = `arg = ${arg}`;
+```

packages/eslint-plugin/src/rules/restrict-template-expressions.ts

@@ -11,6 +11,7 @@ type Options = [
     allowBoolean?: boolean;
     allowAny?: boolean;
     allowNullish?: boolean;
+    allowRegExp?: boolean;
   },
 ];
 
@@ -37,6 +38,7 @@ export default util.createRule<Options, MessageId>({
           allowBoolean: { type: 'boolean' },
           allowAny: { type: 'boolean' },
           allowNullish: { type: 'boolean' },
+          allowRegExp: { type: 'boolean' },
         },
       },
     ],
@@ -76,6 +78,13 @@ export default util.createRule<Options, MessageId>({
         return true;
       }
 
+      if (
+        options.allowRegExp &&
+        util.getTypeName(typeChecker, type) === 'RegExp'
+      ) {
+        return true;
+      }
+
       if (
         options.allowNullish &&
         util.isTypeFlagSet(type, ts.TypeFlags.Null | ts.TypeFlags.Undefined)

packages/eslint-plugin/tests/rules/restrict-template-expressions.test.ts

@@ -189,11 +189,56 @@ ruleTester.run('restrict-template-expressions', rule, {
         }
       `,
     },
+    // allowRegExp
+    {
+      options: [{ allowRegExp: true }],
+      code: `
+        const arg = new RegExp('foo');
+        const msg = \`arg = \${arg}\`;
+      `,
+    },
+    {
+      options: [{ allowRegExp: true }],
+      code: `
+        const arg = /foo/;
+        const msg = \`arg = \${arg}\`;
+      `,
+    },
+    {
+      options: [{ allowRegExp: true }],
+      code: `
+        declare const arg: string | RegExp;
+        const msg = \`arg = \${arg}\`;
+      `,
+    },
+    {
+      options: [{ allowRegExp: true }],
+      code: `
+        function test<T extends RegExp>(arg: T) {
+          return \`arg = \${arg}\`;
+        }
+      `,
+    },
+    {
+      options: [{ allowRegExp: true }],
+      code: `
+        function test<T extends string | RegExp>(arg: T) {
+          return \`arg = \${arg}\`;
+        }
+      `,
+    },
     // allow ALL
     {
-      options: [{ allowNumber: true, allowBoolean: true, allowNullish: true }],
+      options: [
+        {
+          allowNumber: true,
+          allowBoolean: true,
+          allowNullish: true,
+          allowRegExp: true,
+        },
+      ],
       code: `
-        type All = string | number | boolean | null | undefined;
+        type All = string | number | boolean | null | undefined | RegExp;
         function test<T extends All>(arg: T) {
           return \`arg = \${arg}\`;
         }
@@ -338,6 +383,36 @@ ruleTester.run('restrict-template-expressions', rule, {
         },
       ],
     },
+    {
+      options: [{ allowRegExp: false }],
+      code: `
+        const arg = new RegExp('foo');
+        const msg = \`arg = \${arg}\`;
+      `,
+      errors: [
+        {
+          messageId: 'invalidType',
+          data: { type: 'RegExp' },
+          line: 3,
+          column: 30,
+        },
+      ],
+    },
+    {
+      options: [{ allowRegExp: false }],
+      code: `
+        const arg = /foo/;
+        const msg = \`arg = \${arg}\`;
+      `,
+      errors: [
+        {
+          messageId: 'invalidType',
+          data: { type: 'RegExp' },
+          line: 3,
+          column: 30,
+        },
+      ],
+    },
     // TS 3.9 change
     {
       options: [{ allowAny: true }],