typescript-eslint · JoshuaKGoldberg · Feb 3, 2025 · Jan 13, 2025 · Jan 13, 2025 · Jan 14, 2025
diff --git a/packages/eslint-plugin/src/rules/dot-notation.ts b/packages/eslint-plugin/src/rules/dot-notation.ts
@@ -82,7 +82,7 @@ export default createRule<Options, MessageIds>({
   create(context, [options]) {
     const rules = baseRule.create(context);
     const services = getParserServices(context);
-
+    const checker = services.program.getTypeChecker();
     const allowPrivateClassPropertyAccess =
       options.allowPrivateClassPropertyAccess;
     const allowProtectedClassPropertyAccess =
@@ -126,11 +126,15 @@ export default createRule<Options, MessageIds>({
             return;
           }
           if (propertySymbol == null && allowIndexSignaturePropertyAccess) {
-            const objectType = services.getTypeAtLocation(node.object);
-            const indexType = objectType
-              .getNonNullableType()
-              .getStringIndexType();
-            if (indexType != null) {
+            const objectType = services
+              .getTypeAtLocation(node.object)
+              .getNonNullableType();
+            const indexInfos = checker.getIndexInfosOfType(objectType);
+            if (
+              indexInfos.some(
+                info => info.keyType.flags & ts.TypeFlags.StringLike,
+              )
+            ) {
               return;
             }
           }

diff --git a/packages/eslint-plugin/tests/fixtures/tsconfig.noPropertyAccessFromIndexSignature.json b/packages/eslint-plugin/tests/fixtures/tsconfig.noPropertyAccessFromIndexSignature.json
@@ -0,0 +1,6 @@
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "noPropertyAccessFromIndexSignature": true
+  }
+}
diff --git a/packages/eslint-plugin/tests/rules/dot-notation.test.ts b/packages/eslint-plugin/tests/rules/dot-notation.test.ts
@@ -150,6 +150,62 @@ console.log(x?.['priv_prop']);
       `,
       options: [{ allowProtectedClassPropertyAccess: true }],
     },
+    {
+      code: `
+type Foo = {
+  bar: boolean;
+  [key: \`key_\${string}\`]: number;
+};
+declare const foo: Foo;
+foo['key_baz'];
+      `,
+      languageOptions: {
+        parserOptions: {
+          project: './tsconfig.noPropertyAccessFromIndexSignature.json',
+          projectService: false,
+          tsconfigRootDir: rootPath,
+        },
+      },
+    },
+    {
+      code: `
+type Key = Lowercase<string>;
+type Foo = {
+  BAR: boolean;
+  [key: Lowercase<string>]: number;
+};
+declare const foo: Foo;
+foo['bar'];
+      `,
+      languageOptions: {
+        parserOptions: {
+          project: './tsconfig.noPropertyAccessFromIndexSignature.json',
+          projectService: false,
+          tsconfigRootDir: rootPath,
+        },
+      },
+    },
+    {
+      code: `
+type ExtraKey = \`extra\${string}\`;
+
+type Foo = {
+  foo: string;
+  [extraKey: ExtraKey]: number;
+};
+
+function f<T extends Foo>(x: T) {
+  x['extraKey'];
+}
+      `,
+      languageOptions: {
+        parserOptions: {
+          project: './tsconfig.noPropertyAccessFromIndexSignature.json',
+          projectService: false,
+          tsconfigRootDir: rootPath,
+        },
+      },
+    },
   ],
   invalid: [
     {
@@ -384,5 +440,49 @@ const x = new X();
 x.prop = 'hello';
       `,
     },
+    {
+      code: `
+type Foo = {
+  bar: boolean;
+  [key: \`key_\${string}\`]: number;
+};
+foo['key_baz'];
+      `,
+      errors: [{ messageId: 'useDot' }],
+      output: `
+type Foo = {
+  bar: boolean;
+  [key: \`key_\${string}\`]: number;
+};
+foo.key_baz;
+      `,
+    },
+    {
+      code: `
+type ExtraKey = \`extra\${string}\`;
+
+type Foo = {
+  foo: string;
+  [extraKey: ExtraKey]: number;
+};
+
+function f<T extends Foo>(x: T) {
+  x['extraKey'];
+}
+      `,
+      errors: [{ messageId: 'useDot' }],
+      output: `
+type ExtraKey = \`extra\${string}\`;
+
+type Foo = {
+  foo: string;
+  [extraKey: ExtraKey]: number;
+};
+
+function f<T extends Foo>(x: T) {
+  x.extraKey;
+}
+      `,
+    },
   ],
 });