add support for getInitialProps in Next.js

javascript/ql/src/semmle/javascript/frameworks/Next.qll

@@ -67,12 +67,23 @@ private module NextJS {
 
     NextJSStaticPropsStep() {
       pageModule = getAPagesModule() and
-      this = pageModule.getAnExportedValue("getStaticProps").getAFunctionValue()
+      this = pageModule.getAnExportedValue("default").getAFunctionValue()
     }
 
     override predicate step(DataFlow::Node pred, DataFlow::Node succ) {
-      pred = this.getAReturn().getALocalSource().getAPropertyWrite("props").getRhs() and
-      succ = pageModule.getAnExportedValue("default").getAFunctionValue().getParameter(0)
+      (
+        pred =
+          pageModule
+              .getAnExportedValue("getStaticProps")
+              .getAFunctionValue()
+              .getAReturn()
+              .getALocalSource()
+              .getAPropertyWrite("props")
+              .getRhs()
+        or
+        pred = this.getAPropertyWrite("getInitialProps").getRhs().getAFunctionValue().getAReturn()
+      ) and
+      succ = this.getParameter(0)
     }
   }
 }

javascript/ql/test/library-tests/frameworks/Next/pages/[my-fallback-id].jsx

@@ -15,7 +15,12 @@ export async function getStaticProps({ params }) {
     }
 }
 
-export default function Post({ taint }) {
+export default function Post({ taint, stars }) {
     sink(taint);
+    sink(stars);
     return <span />;
 }
+
+Post.getInitialProps = async (ctx) => {
+    return { stars: source(2) }
+}

javascript/ql/test/library-tests/frameworks/Next/tests.expected

@@ -2,3 +2,4 @@ remoteFlow
 | pages/[my-fallback-id].jsx:9:40:9:45 | params |
 dataFlow
 | pages/[my-fallback-id].jsx:13:20:13:27 | source() | pages/[my-fallback-id].jsx:19:10:19:14 | taint |
+| pages/[my-fallback-id].jsx:25:21:25:29 | source(2) | pages/[my-fallback-id].jsx:20:10:20:14 | stars |