Repository: facebook/react
Pull request: [Flight] Copy the name field of a serialized function debug value

This ensures that if the name is set manually after the declaration, then we get that name when we log the value. For example Node.js `Response` is declared as `_Response` and then later assigned a new name.

We should probably really serialize all static enumerable properties but "name" is non-enumerable so it's still a special case.


Changed files:
filename: packages/react-client/src/ReactFlightClient.js
patch: @@ -1969,6 +1969,44 @@ function createModel(response: Response, model: any): any {
   return model;
 }
 
+const mightHaveStaticConstructor = /\bclass\b.*\bstatic\b/;
+
+function getInferredFunctionApproximate(code: string): () => void {
+  let slicedCode;
+  if (code.startsWith('Object.defineProperty(')) {
+    slicedCode = code.slice('Object.defineProperty('.length);
+  } else if (code.startsWith('(')) {
+    slicedCode = code.slice(1);
+  } else {
+    slicedCode = code;
+  }
+  if (slicedCode.startsWith('async function')) {
+    const idx = slicedCode.indexOf('(', 14);
+    if (idx !== -1) {
+      const name = slicedCode.slice(14, idx).trim();
+      // eslint-disable-next-line no-eval
+      return (0, eval)('({' + JSON.stringify(name) + ':async function(){}})')[
+        name
+      ];
+    }
+  } else if (slicedCode.startsWith('function')) {
+    const idx = slicedCode.indexOf('(', 8);
+    if (idx !== -1) {
+      const name = slicedCode.slice(8, idx).trim();
+      // eslint-disable-next-line no-eval
+      return (0, eval)('({' + JSON.stringify(name) + ':function(){}})')[name];
+    }
+  } else if (slicedCode.startsWith('class')) {
+    const idx = slicedCode.indexOf('{', 5);
+    if (idx !== -1) {
+      const name = slicedCode.slice(5, idx).trim();
+      // eslint-disable-next-line no-eval
+      return (0, eval)('({' + JSON.stringify(name) + ':class{}})')[name];
+    }
+  }
+  return function () {};
+}
+
 function parseModelString(
   response: Response,
   parentObject: Object,
@@ -2158,41 +2196,37 @@ function parseModelString(
           // This should not compile to eval() because then it has local scope access.
           const code = value.slice(2);
           try {
-            // eslint-disable-next-line no-eval
-            return (0, eval)(code);
+            // If this might be a class constructor with a static initializer or
+            // static constructor then don't eval it. It might cause unexpected
+            // side-effects. Instead, fallback to parsing out the function type
+            // and name.
+            if (!mightHaveStaticConstructor.test(code)) {
+              // eslint-disable-next-line no-eval
+              return (0, eval)(code);
+            }
           } catch (x) {
-            // We currently use this to express functions so we fail parsing it,
-            // let's just return a blank function as a place holder.
-            if (code.startsWith('(async function')) {
-              const idx = code.indexOf('(', 15);
-              if (idx !== -1) {
-                const name = code.slice(15, idx).trim();
-                // eslint-disable-next-line no-eval
-                return (0, eval)(
-                  '({' + JSON.stringify(name) + ':async function(){}})',
-                )[name];
-              }
-            } else if (code.startsWith('(function')) {
-              const idx = code.indexOf('(', 9);
-              if (idx !== -1) {
-                const name = code.slice(9, idx).trim();
-                // eslint-disable-next-line no-eval
-                return (0, eval)(
-                  '({' + JSON.stringify(name) + ':function(){}})',
-                )[name];
-              }
-            } else if (code.startsWith('(class')) {
-              const idx = code.indexOf('{', 6);
+            // Fallthrough to fallback case.
+          }
+          // We currently use this to express functions so we fail parsing it,
+          // let's just return a blank function as a place holder.
+          let fn;
+          try {
+            fn = getInferredFunctionApproximate(code);
+            if (code.startsWith('Object.defineProperty(')) {
+              const DESCRIPTOR = ',"name",{value:"';
+              const idx = code.lastIndexOf(DESCRIPTOR);
               if (idx !== -1) {
-                const name = code.slice(6, idx).trim();
-                // eslint-disable-next-line no-eval
-                return (0, eval)('({' + JSON.stringify(name) + ':class{}})')[
-                  name
-                ];
+                const name = JSON.parse(
+                  code.slice(idx + DESCRIPTOR.length - 1, code.length - 2),
+                );
+                // $FlowFixMe[cannot-write]
+                Object.defineProperty(fn, 'name', {value: name});
               }
             }
-            return function () {};
+          } catch (_) {
+            fn = function () {};
           }
+          return fn;
         }
         // Fallthrough
       }

filename: packages/react-client/src/__tests__/ReactFlight-test.js
patch: @@ -3239,6 +3239,8 @@ describe('ReactFlight', () => {
     }
     Object.defineProperty(MyClass.prototype, 'y', {enumerable: true});
 
+    Object.defineProperty(MyClass, 'name', {value: 'MyClassName'});
+
     function ServerComponent() {
       console.log('hi', {
         prop: 123,
@@ -3341,6 +3343,7 @@ describe('ReactFlight', () => {
     const instance = mockConsoleLog.mock.calls[0][1].instance;
     expect(typeof Class).toBe('function');
     expect(Class.prototype.constructor).toBe(Class);
+    expect(Class.name).toBe('MyClassName');
     expect(instance instanceof Class).toBe(true);
     expect(Object.getPrototypeOf(instance)).toBe(Class.prototype);
     expect(instance.x).toBe(1);

filename: packages/react-server/src/ReactFlightServer.js
patch: @@ -4848,9 +4848,18 @@ function renderDebugModel(
       return existingReference;
     }
 
+    // $FlowFixMe[method-unbinding]
+    const functionBody: string = Function.prototype.toString.call(value);
+
+    const name = value.name;
     const serializedValue = serializeEval(
-      // $FlowFixMe[method-unbinding]
-      '(' + Function.prototype.toString.call(value) + ')',
+      typeof name === 'string'
+        ? 'Object.defineProperty(' +
+            functionBody +
+            ',"name",{value:' +
+            JSON.stringify(name) +
+            '})'
+        : '(' + functionBody + ')',
     );
     request.pendingDebugChunks++;
     const id = request.nextChunkId++;