Function parse_semver_core 

fn parse_semver_core(v: &str) -> Option<(u64, u64, u64)>

Parse a leading major.minor.patch out of a version string, ignoring any -prerelease or +build suffix. Returns None for anything that doesn’t start with three dot-separated integers (e.g. a local build’s labeled version, which normally lives in a local-* channel rather than under a released stable channel anyway). Callers must treat None as “can’t compare” — never guess.