feat: Add experimental flag enableUnhandledCPPExceptionsV2 on iOS (getsentry#4975)

* feat: Add experimental flag `enableUnhandledCPPExceptionsV2` on iOS

* Adds changelog

* Use an RNSentryExperimentalOptions Obj-C wrapper to access the property

* Fixes lint issues

Author: antonis

CHANGELOG.md

@@ -8,6 +8,20 @@
 
 ## Unreleased
 
+### Features
+
+- Add experimental flag `enableUnhandledCPPExceptionsV2` on iOS ([#4975](https://github.com/getsentry/sentry-react-native/pull/4975))
+
+  ```js
+  import * as Sentry from '@sentry/react-native';
+
+  Sentry.init({
+    _experiments: {
+      enableUnhandledCPPExceptionsV2: true,
+    },
+  });
+  ```
+
 ### Dependencies
 
 - Bump CLI from v2.46.0 to v2.47.0 ([#4979](https://github.com/getsentry/sentry-react-native/pull/4979))

packages/core/RNSentryCocoaTester/RNSentryCocoaTesterTests/RNSentryTests.mm

@@ -239,6 +239,82 @@ - (void)testCreateOptionsWithDictionarySpotlightZero
     XCTAssertFalse(actualOptions.enableSpotlight, @"Did not disable spotlight");
 }
 
+- (void)testCreateOptionsWithDictionaryEnableUnhandledCPPExceptionsV2Enabled
+{
+    RNSentry *rnSentry = [[RNSentry alloc] init];
+    NSError *error = nil;
+
+    NSDictionary *_Nonnull mockedReactNativeDictionary = @{
+        @"dsn" : @"https://abcd@efgh.ingest.sentry.io/123456",
+        @"_experiments" : @ {
+            @"enableUnhandledCPPExceptionsV2" : @YES,
+        },
+    };
+    SentryOptions *actualOptions = [rnSentry createOptionsWithDictionary:mockedReactNativeDictionary
+                                                                   error:&error];
+
+    XCTAssertNotNil(actualOptions, @"Did not create sentry options");
+    XCTAssertNil(error, @"Should not pass no error");
+
+    id experimentalOptions = [actualOptions valueForKey:@"experimental"];
+    XCTAssertNotNil(experimentalOptions, @"Experimental options should not be nil");
+
+    BOOL enableUnhandledCPPExceptions =
+        [[experimentalOptions valueForKey:@"enableUnhandledCPPExceptionsV2"] boolValue];
+    XCTAssertTrue(
+        enableUnhandledCPPExceptions, @"enableUnhandledCPPExceptionsV2 should be enabled");
+}
+
+- (void)testCreateOptionsWithDictionaryEnableUnhandledCPPExceptionsV2Disabled
+{
+    RNSentry *rnSentry = [[RNSentry alloc] init];
+    NSError *error = nil;
+
+    NSDictionary *_Nonnull mockedReactNativeDictionary = @{
+        @"dsn" : @"https://abcd@efgh.ingest.sentry.io/123456",
+        @"_experiments" : @ {
+            @"enableUnhandledCPPExceptionsV2" : @NO,
+        },
+    };
+    SentryOptions *actualOptions = [rnSentry createOptionsWithDictionary:mockedReactNativeDictionary
+                                                                   error:&error];
+
+    XCTAssertNotNil(actualOptions, @"Did not create sentry options");
+    XCTAssertNil(error, @"Should not pass no error");
+
+    id experimentalOptions = [actualOptions valueForKey:@"experimental"];
+    XCTAssertNotNil(experimentalOptions, @"Experimental options should not be nil");
+
+    BOOL enableUnhandledCPPExceptions =
+        [[experimentalOptions valueForKey:@"enableUnhandledCPPExceptionsV2"] boolValue];
+    XCTAssertFalse(
+        enableUnhandledCPPExceptions, @"enableUnhandledCPPExceptionsV2 should be disabled");
+}
+
+- (void)testCreateOptionsWithDictionaryEnableUnhandledCPPExceptionsV2Default
+{
+    RNSentry *rnSentry = [[RNSentry alloc] init];
+    NSError *error = nil;
+
+    NSDictionary *_Nonnull mockedReactNativeDictionary = @{
+        @"dsn" : @"https://abcd@efgh.ingest.sentry.io/123456",
+    };
+    SentryOptions *actualOptions = [rnSentry createOptionsWithDictionary:mockedReactNativeDictionary
+                                                                   error:&error];
+
+    XCTAssertNotNil(actualOptions, @"Did not create sentry options");
+    XCTAssertNil(error, @"Should not pass no error");
+
+    // Test that when no _experiments are provided, the experimental option defaults to false
+    id experimentalOptions = [actualOptions valueForKey:@"experimental"];
+    XCTAssertNotNil(experimentalOptions, @"Experimental options should not be nil");
+
+    BOOL enableUnhandledCPPExceptions =
+        [[experimentalOptions valueForKey:@"enableUnhandledCPPExceptionsV2"] boolValue];
+    XCTAssertFalse(
+        enableUnhandledCPPExceptions, @"enableUnhandledCPPExceptionsV2 should default to disabled");
+}
+
 - (void)testPassesErrorOnWrongDsn
 {
     RNSentry *rnSentry = [[RNSentry alloc] init];

packages/core/ios/RNSentry.mm

@@ -49,6 +49,7 @@
 #    import "RNSentryRNSScreen.h"
 #endif
 
+#import "RNSentryExperimentalOptions.h"
 #import "RNSentryVersion.h"
 
 @interface
@@ -225,6 +226,14 @@ - (SentryOptions *_Nullable)createOptionsWithDictionary:(NSDictionary *_Nonnull)
     // Failed requests can only be enabled in one SDK to avoid duplicates
     sentryOptions.enableCaptureFailedRequests = NO;
 
+    NSDictionary *experiments = options[@"_experiments"];
+    if (experiments != nil && [experiments isKindOfClass:[NSDictionary class]]) {
+        BOOL enableUnhandledCPPExceptions =
+            [experiments[@"enableUnhandledCPPExceptionsV2"] boolValue];
+        [RNSentryExperimentalOptions setEnableUnhandledCPPExceptionsV2:enableUnhandledCPPExceptions
+                                                         sentryOptions:sentryOptions];
+    }
+
     return sentryOptions;
 }
 

packages/core/ios/RNSentryExperimentalOptions.h

@@ -0,0 +1,26 @@
+#import <Foundation/Foundation.h>
+
+@class SentryOptions;
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface RNSentryExperimentalOptions : NSObject
+
+/**
+ * Sets the enableUnhandledCPPExceptionsV2 experimental option on SentryOptions
+ * @param sentryOptions The SentryOptions instance to configure
+ * @param enabled Whether to enable unhandled C++ exceptions V2
+ */
++ (void)setEnableUnhandledCPPExceptionsV2:(BOOL)enabled
+                            sentryOptions:(SentryOptions *)sentryOptions;
+
+/**
+ * Gets the current value of enableUnhandledCPPExceptionsV2 experimental option
+ * @param sentryOptions The SentryOptions instance to read from
+ * @return The current value of enableUnhandledCPPExceptionsV2
+ */
++ (BOOL)getEnableUnhandledCPPExceptionsV2:(SentryOptions *)sentryOptions;
+
+@end
+
+NS_ASSUME_NONNULL_END

packages/core/ios/RNSentryExperimentalOptions.m

@@ -0,0 +1,22 @@
+#import "RNSentryExperimentalOptions.h"
+@import Sentry;
+
+@implementation RNSentryExperimentalOptions
+
++ (void)setEnableUnhandledCPPExceptionsV2:(BOOL)enabled sentryOptions:(SentryOptions *)sentryOptions
+{
+    if (sentryOptions == nil) {
+        return;
+    }
+    sentryOptions.experimental.enableUnhandledCPPExceptionsV2 = enabled;
+}
+
++ (BOOL)getEnableUnhandledCPPExceptionsV2:(SentryOptions *)sentryOptions
+{
+    if (sentryOptions == nil) {
+        return NO;
+    }
+    return sentryOptions.experimental.enableUnhandledCPPExceptionsV2;
+}
+
+@end

packages/core/src/js/options.ts

@@ -253,6 +253,17 @@ export interface BaseReactNativeOptions {
      * This will be removed in the next major version.
      */
     replaysOnErrorSampleRate?: number;
+
+    /**
+     * Experiment: A more reliable way to report unhandled C++ exceptions in iOS.
+     *
+     * This approach hooks into all instances of the `__cxa_throw` function, which provides a more comprehensive and consistent exception handling across an app’s runtime, regardless of the number of C++ modules or how they’re linked. It helps in obtaining accurate stack traces.
+     *
+     * - Note: The mechanism of hooking into `__cxa_throw` could cause issues with symbolication on iOS due to caching of symbol references.
+     *
+     * @default false
+     */
+    enableUnhandledCPPExceptionsV2?: boolean;
   };
 
   /**

samples/react-native/src/App.tsx

@@ -171,6 +171,9 @@ Sentry.init({
   // This should be disabled when manually initializing the native SDK
   // Note that options from JS are not passed to the native SDKs when initialized manually
   autoInitializeNativeSdk: true,
+  _experiments: {
+    enableUnhandledCPPExceptionsV2: true,
+  },
 });
 
 const Stack = isMobileOs