Fix: sourceType not correctly set in AST when provided in options.

.gitignore

@@ -7,3 +7,4 @@ _test.js
 .vscode
 yarn.lock
 .eslint-release-info.json
+.idea

parser.js

@@ -34,6 +34,10 @@ exports.parseForESLint = function parseForESLint(code, options) {
     }
 
     const ast = parse(code, options);
+    if (options.sourceType && ast && ast.type === "Program") {
+        ast.sourceType = options.sourceType;
+    }
+
     const extraOptions = {
         sourceType: ast.sourceType
     };

tests/lib/scope-analysis.js

@@ -370,4 +370,26 @@ function test(file: Blob) {
 
         expect(messages).toStrictEqual([]);
     });
+
+    test("https://github.com/bradzacher/eslint-plugin-typescript/issues/255", () => {
+        const code = `
+window.whatevs = {
+  myFunc() {
+    console.log('yep');
+  }
+};
+`;
+        const config = {
+            parser: "typescript-eslint-parser",
+            parserOptions: {
+                sourceType: "module"
+            },
+            rules: {
+                strict: "error"
+            }
+        };
+        const messages = linter.verify(code, config, { filename: "issue255.ts" });
+
+        expect(messages).toStrictEqual([]);
+    });
 });