---

name: webrtc/api/assert-notreached-in-default-interface-methods description: When providing default implementations for virtual methods in public interface base classes under api/ or *_interface.h, assert RTC_CHECK_NOTREACHED() or RTC_DCHECK_NOTREACHED() instead of empty bodies or silent dummy returns rubric: correctness severity: should_fix

Rule. When providing default implementations for virtual methods (such as newly added methods or setters) in public interface base classes (under api/ or *_interface.h), assert RTC_CHECK_NOTREACHED() or RTC_DCHECK_NOTREACHED(). Do not leave empty no-op bodies or return silent dummy values (such as return false;) that cannot fulfill the method's contract. If the method returns a non-void value and debug assertions are non-fatal, return an appropriate fallback value or use RTC_CHECK_NOTREACHED() to terminate execution.

Why. Empty default implementations or dummy return values silently swallow invocations and mask bugs when an unimplemented or unsupported method is called at runtime. Asserting RTC_CHECK_NOTREACHED() or RTC_DCHECK_NOTREACHED() preserves compile-time backward compatibility for downstream subclasses while ensuring accidental or unsupported runtime calls fail fast during development and testing.

Examples

Bad:

// Bad: Silent dummy return masks unimplemented calls that callers expect to succeed:
virtual bool RemoveIceCandidates(const std::vector<Candidate>& candidates) {
  return false;
}

// Bad: Empty no-op body silently ignores unsupported setter invocations:
virtual void SetCaptureTime(std::optional<Timestamp> capture_time) {}
virtual void SetPayloadType(uint8_t payload_type) {}

Good:

// Good: Fails immediately if invoked on an un-overridden instance:
virtual bool RemoveIceCandidates(const std::vector<Candidate>& candidates) {
  RTC_CHECK_NOTREACHED();
}

// Good: Asserts in debug builds if invoked when capability is unsupported:
virtual void SetCaptureTime(std::optional<Timestamp> capture_time) {
  RTC_DCHECK_NOTREACHED();
}
virtual void SetPayloadType(uint8_t payload_type) {
  RTC_DCHECK_NOTREACHED();
}