Add codegen for MixedType diffing (#52266)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/52266

Native components may use `MixedType` properties in rare cases to hold untyped data. This diff adds support for serializing and prop diffing these types of props so that all of the props and object fields would be included in prop diffing results.

Changelog: [Internal]

Reviewed By: mdvacca

Differential Revision: D77307169

fbshipit-source-id: ae6b00207ef857c9cfa4bdf9c235972915410a29

packages/react-native-codegen/e2e/deep_imports/__tests__/components/__snapshots__/GeneratePropsCpp-test.js.snap

@@ -737,6 +737,9 @@ folly::dynamic MixedPropNativeComponentViewProps::getDiffProps(
   }
   folly::dynamic result = HostPlatformViewProps::getDiffProps(prevProps);
   
+  if (mixedProp != oldProps->mixedProp) {
+    result[\\"mixedProp\\"] = mixedProp;
+  }
   return result;
 }
 #endif

packages/react-native-codegen/e2e/namespaced/__tests__/components/__snapshots__/GeneratePropsCpp-test.js.snap

@@ -737,6 +737,9 @@ folly::dynamic MixedPropNativeComponentViewProps::getDiffProps(
   }
   folly::dynamic result = HostPlatformViewProps::getDiffProps(prevProps);
   
+  if (mixedProp != oldProps->mixedProp) {
+    result[\\"mixedProp\\"] = mixedProp;
+  }
   return result;
 }
 #endif

packages/react-native-codegen/src/generators/components/GeneratePropsCpp.js

@@ -152,6 +152,10 @@ function generatePropsDiffString(
     result["${prop.name}"] = toDynamic(${prop.name});
   }`;
         case 'MixedTypeAnnotation':
+          return `
+  if (${prop.name} != oldProps->${prop.name}) {
+    result["${prop.name}"] = ${prop.name};
+  }`;
         default:
           // TODO: Implement diffProps for complex types
           return '';

packages/react-native-codegen/src/generators/components/GeneratePropsH.js

@@ -755,10 +755,8 @@ function generateStruct(
         case 'Int32TypeAnnotation':
         case 'DoubleTypeAnnotation':
         case 'FloatTypeAnnotation':
-          return `result["${name}"] = ${name};`;
         case 'MixedTypeAnnotation':
-          // MixedTypeAnnotation does not support prop diffing codegen
-          return '';
+          return `result["${name}"] = ${name};`;
         default:
           return `result["${name}"] = ::facebook::react::toDynamic(${name});`;
       }

packages/react-native-codegen/src/generators/components/__tests__/__snapshots__/GeneratePropsCpp-test.js.snap

@@ -1152,6 +1152,9 @@ folly::dynamic MixedPropNativeComponentProps::getDiffProps(
   }
   folly::dynamic result = HostPlatformViewProps::getDiffProps(prevProps);
   
+  if (mixedProp != oldProps->mixedProp) {
+    result[\\"mixedProp\\"] = mixedProp;
+  }
   return result;
 }
 #endif