diff options
| -rw-r--r-- | src/librustc/ty/context.rs | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs index bf412b57007..77964f6845b 100644 --- a/src/librustc/ty/context.rs +++ b/src/librustc/ty/context.rs @@ -396,8 +396,16 @@ impl<'tcx> TypeckTables<'tcx> { self.upvar_capture_map[&upvar_id] } - /// Validate that a NodeId can safely be converted to an ItemLocalId for - /// this table. + /// Validate that the given HirId (respectively its `local_id` part) can be + /// safely used as a key in the tables of this TypeckTable. For that to be + /// the case, the HirId must have the same `owner` as all the other IDs in + /// this table (signified by the `local_id_root` field). Otherwise the HirId + /// would be in a different frame of reference and using its `local_id` + /// would result in lookup errors, or worse, in silently wrong data being + /// stored/returned. + /// + /// Therefore it is advised to call this method anytime before using a given + /// HirId::local_id as a key. #[inline] pub fn validate_hir_id(&self, hir_id: hir::HirId) { #[cfg(debug_assertions)] |