diff options
| -rw-r--r-- | compiler/rustc_hir/src/lang_items.rs | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/compiler/rustc_hir/src/lang_items.rs b/compiler/rustc_hir/src/lang_items.rs index e7398fd2226..c148dc7f53b 100644 --- a/compiler/rustc_hir/src/lang_items.rs +++ b/compiler/rustc_hir/src/lang_items.rs @@ -45,7 +45,16 @@ impl LanguageItems { pub fn set(&mut self, item: LangItem, def_id: DefId) { self.items[item as usize] = Some(def_id); - self.reverse_items.insert(def_id, item); + let preexisting = self.reverse_items.insert(def_id, item); + + // This needs to be a bijection. + if let Some(preexisting) = preexisting { + panic!( + "For the bijection of LangItem <=> DefId to work,\ + one item DefId may only be assigned one LangItem. \ + Separate the LangItem definitions for {item:?} and {preexisting:?}." + ); + } } pub fn from_def_id(&self, def_id: DefId) -> Option<LangItem> { |