Support ts-expect-error for specific version ranges (#1021)

.changeset/sixty-items-sin.md

@@ -0,0 +1,5 @@
+---
+"@definitelytyped/eslint-plugin": patch
+---
+
+Support ts-expect-error for specific version ranges

packages/eslint-plugin/package.json

@@ -24,7 +24,8 @@
   "dependencies": {
     "@definitelytyped/utils": "workspace:*",
     "@typescript-eslint/types": "^7.14.1",
-    "@typescript-eslint/utils": "^7.14.1"
+    "@typescript-eslint/utils": "^7.14.1",
+    "semver": "^7.5.4"
   },
   "peerDependencies": {
     "@typescript-eslint/eslint-plugin": "^7.14.1",
@@ -36,10 +37,13 @@
   "devDependencies": {
     "@definitelytyped/eslint-plugin": "link:",
     "@types/eslint": "^8.56.2",
+    "@types/semver": "^7.5.6",
     "glob": "^10.3.10",
     "jest-file-snapshot": "^0.5.0",
     "strip-ansi": "^6.0.1",
-    "typescript": "^5.5.2"
+    "typescript": "^5.5.2",
+    "typescript-5.4": "npm:typescript@~5.4.0-0",
+    "typescript-5.5": "npm:typescript@~5.5.0-0"
   },
   "engines": {
     "node": ">=18.18.0"

packages/eslint-plugin/src/rules/expect.ts

@@ -4,6 +4,7 @@ import type * as ts from "typescript";
 import path from "path";
 import fs from "fs";
 import { ReportDescriptorMessageData } from "@typescript-eslint/utils/ts-eslint";
+import * as semver from "semver";
 
 type TSModule = typeof ts;
 
@@ -241,6 +242,10 @@ const zeroSourceLocation: Readonly<TSESTree.SourceLocation> = {
 
 const expectTypeToken = "$ExpectType";
 
+// Based on TypeScript's scanner.ts
+const expectErrorSingleLine = /^\/\/\/?\s*@ts-expect-error\s+(.*)/
+const expectErrorMultiLine = /^(?:\/|\*)*\s*@ts-expect-error\s+(.*)/;
+
 function walk(
   getLocFromIndex: (index: number) => Readonly<TSESTree.Position>,
   report: Reporter,
@@ -259,6 +264,26 @@ function walk(
     // Don't care about emit errors.
     const diagnostics = ts.getPreEmitDiagnostics(program, sourceFile);
     for (const diagnostic of diagnostics) {
+      if (diagnostic.code === 2578) {
+        // This is a ts-expect-error; parse "// @ts-expect-error <range>" and ignore when the current version is outside that range.
+        const text = sourceFile.text.slice(diagnostic.start!, diagnostic.start! + diagnostic.length!);
+        const match = text.match(expectErrorSingleLine) || text.match(expectErrorMultiLine);
+        if (match) {
+          let range: semver.Range | undefined;
+          try {
+            range = new semver.Range(match[1].trim())
+          } catch {
+            // Ignore any parsing errors.
+          }
+
+          if (range) {
+            if (!semver.satisfies(versionName, range, { loose: true })) {
+              continue;
+            }
+          }
+        }
+      }
+
       addDiagnosticFailure(diagnostic);
     }
 

packages/eslint-plugin/test/__file_snapshots__/types/expect-error-range/expect-error-range-tests.ts.lint

@@ -0,0 +1,80 @@
+types/expect-error-range/expect-error-range-tests.ts
+   8:11  error  [email protected] compile error: 
+Type 'string | undefined' is not assignable to type 'string'.
+  Type 'undefined' is not assignable to type 'string'  @definitelytyped/expect
+  11:11  error  [email protected] compile error: 
+Type 'string' is not assignable to type 'never'                                                                      @definitelytyped/expect
+  16:5   error  [email protected] compile error: 
+Unused '@ts-expect-error' directive                                                                                  @definitelytyped/expect
+  20:5   error  [email protected] compile error: 
+Unused '@ts-expect-error' directive                                                                                  @definitelytyped/expect
+  27:5   error  [email protected] compile error: 
+Unused '@ts-expect-error' directive                                                                                  @definitelytyped/expect
+  31:5   error  [email protected] compile error: 
+Unused '@ts-expect-error' directive                                                                                  @definitelytyped/expect
+
+✖ 6 problems (6 errors, 0 warnings)
+
+==== types/expect-error-range/expect-error-range-tests.ts ====
+
+    // In TypeScript <5.5, elem will have type "string",
+    // but 5.5 it will be "string | undefined".
+    const elem = ["value", undefined].filter(x => x != null)[0];
+
+
+    {
+        // This should error in 5.4, but not 5.5.
+        const test1: string = elem;
+              ~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Type 'string | undefined' is not assignable to type 'string'.
+!!!                        :   Type 'undefined' is not assignable to type 'string'.
+
+        // This should error in 5.5, but not 5.4.
+        const test2: undefined extends typeof elem ? typeof elem : never = elem;
+              ~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Type 'string' is not assignable to type 'never'.
+    }
+
+    {
+        // This should error in 5.5, but not 5.4.
+        // @ts-expect-error
+        ~~~~~~~~~~~~~~~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Unused '@ts-expect-error' directive.
+        const test1: string = elem;
+
+        // This should error in 5.4, but not 5.5.
+        // @ts-expect-error
+        ~~~~~~~~~~~~~~~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Unused '@ts-expect-error' directive.
+        const test2: undefined extends typeof elem ? typeof elem : never = elem;
+    }
+
+    // These should be treated as though there is no range.
+    {
+        // This should error in 5.5, but not 5.4.
+        // @ts-expect-error random non-range text
+        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Unused '@ts-expect-error' directive.
+        const test1: string = elem;
+
+        // This should error in 5.4, but not 5.5.
+        // @ts-expect-error random non-range text
+        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! @definitelytyped/expect: [email protected] compile error: 
+!!!                        : Unused '@ts-expect-error' directive.
+        const test2: undefined extends typeof elem ? typeof elem : never = elem;
+    }
+
+    // None of these expects should error.
+    {
+        // @ts-expect-error <5.5
+        const test1: string = elem;
+
+        // @ts-expect-error >=5.5
+        const test2: undefined extends typeof elem ? typeof elem : never = elem;
+    }

packages/eslint-plugin/test/__file_snapshots__/types/expect-error-range/index.d.ts.lint

@@ -0,0 +1,5 @@
+No errors
+
+==== types/expect-error-range/index.d.ts ====
+
+    export const value: number;

packages/eslint-plugin/test/fixtures/types/expect-error-range/.eslintrc.js

@@ -0,0 +1,10 @@
+module.exports = {
+  settings: {
+    dt: {
+      versionsToTest: [
+        { versionName: "5.4", path: "typescript-5.4" },
+        { versionName: "5.5", path: "typescript-5.5" }
+      ]
+    }
+  },
+};

packages/eslint-plugin/test/fixtures/types/expect-error-range/expect-error-range-tests.ts

@@ -0,0 +1,43 @@
+// In TypeScript <5.5, elem will have type "string",
+// but 5.5 it will be "string | undefined".
+const elem = ["value", undefined].filter(x => x != null)[0];
+
+
+{
+    // This should error in 5.4, but not 5.5.
+    const test1: string = elem;
+
+    // This should error in 5.5, but not 5.4.
+    const test2: undefined extends typeof elem ? typeof elem : never = elem;
+}
+
+{
+    // This should error in 5.5, but not 5.4.
+    // @ts-expect-error
+    const test1: string = elem;
+
+    // This should error in 5.4, but not 5.5.
+    // @ts-expect-error
+    const test2: undefined extends typeof elem ? typeof elem : never = elem;
+}
+
+// These should be treated as though there is no range.
+{
+    // This should error in 5.5, but not 5.4.
+    // @ts-expect-error random non-range text
+    const test1: string = elem;
+
+    // This should error in 5.4, but not 5.5.
+    // @ts-expect-error random non-range text
+    const test2: undefined extends typeof elem ? typeof elem : never = elem;
+}
+
+// None of these expects should error.
+{
+    // @ts-expect-error <5.5
+    const test1: string = elem;
+
+    // @ts-expect-error >=5.5
+    const test2: undefined extends typeof elem ? typeof elem : never = elem;
+}
+

packages/eslint-plugin/test/fixtures/types/expect-error-range/index.d.ts

@@ -0,0 +1 @@
+export const value: number;

packages/eslint-plugin/test/fixtures/types/expect-error-range/package.json

@@ -0,0 +1,5 @@
+{
+    "name": "@types/expect-error-range",
+    "version": "2.0.9999",
+    "owners": []
+}

packages/eslint-plugin/test/fixtures/types/expect-error-range/tsconfig.json

@@ -0,0 +1,20 @@
+{
+    "compilerOptions": {
+        "module": "commonjs",
+        "lib": [
+            "es6",
+            "dom"
+        ],
+        "noImplicitAny": true,
+        "noImplicitThis": true,
+        "strictFunctionTypes": true,
+        "strictNullChecks": true,
+        "types": [],
+        "noEmit": true,
+        "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+        "index.d.ts",
+        "expect-error-range-tests.ts"
+    ]
+}