message: Use pointer eq/hash for SourceIdInner
diff: @@ -337,11 +337,11 @@ impl SourceId {
  }
  pub fn full_eq(&self, other: &SourceId) -> bool {
  - self.inner == other.inner
  + ptr::eq(self.inner, other.inner)
  }
  pub fn full_hash<S: hash::Hasher>(&self, into: &mut S) {
  - self.inner.hash(into)
  + (self.inner as *const SourceIdInner).hash(into)
  }
  }
  