Static constants take the k prefix (readability-identifier-naming), and
SpanGuardScope.cpp no longer names anything from <opentelemetry/metrics/noop.h>
since it calls noopMeter(). Both fail CI under warnings-as-errors.
The helper's docstring also claimed NoopMeterProvider hides the base
two-argument GetMeter; it declares that overload itself, so the only
detail worth sharing is the version.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>