Auto merge of #13223 - lowr:fix/hir-proj-normalization, r=flodiebold

[rust.git] / crates / hir-ty / src / utils.rs

diff --git a/crates/hir-ty/src/utils.rs b/crates/hir-ty/src/utils.rs
index 83319755da73aa5fbce84053edf06cbbcd9a7e8f..d6638db02851183c5f080dc8cfc3fed5503ae76c 100644 (file)
--- a/crates/hir-ty/src/utils.rs
+++ b/crates/hir-ty/src/utils.rs
@@ -176,10 +176,19 @@ pub(crate) fn generics(db: &dyn DefDatabase, def: GenericDefId) -> Generics {
     let parent_generics = parent_generic_def(db, def).map(|def| Box::new(generics(db, def)));
     if parent_generics.is_some() && matches!(def, GenericDefId::TypeAliasId(_)) {
         let params = db.generic_params(def);
+        let parent_params = &parent_generics.as_ref().unwrap().params;
         let has_consts =
             params.iter().any(|(_, x)| matches!(x, TypeOrConstParamData::ConstParamData(_)));
-        return if has_consts {
-            // XXX: treat const generic associated types as not existing to avoid crashes (#11769)
+        let parent_has_consts =
+            parent_params.iter().any(|(_, x)| matches!(x, TypeOrConstParamData::ConstParamData(_)));
+        return if has_consts || parent_has_consts {
+            // XXX: treat const generic associated types as not existing to avoid crashes
+            // (#11769)
+            //
+            // Note: Also crashes when the parent has const generics (also even if the GAT
+            // doesn't use them), see `tests::regression::gat_crash_3` for an example.
+            // Avoids that by disabling GATs when the parent (i.e. `impl` block) has
+            // const generics (#12193).
             //
             // Chalk expects the inner associated type's parameters to come
             // *before*, not after the trait's generics as we've always done it.
@@ -264,12 +273,8 @@ pub(crate) fn param_idx(&self, param: TypeOrConstParamId) -> Option<usize> {
 
     fn find_param(&self, param: TypeOrConstParamId) -> Option<(usize, &TypeOrConstParamData)> {
         if param.parent == self.def {
-            let (idx, (_local_id, data)) = self
-                .params
-                .iter()
-                .enumerate()
-                .find(|(_, (idx, _))| *idx == param.local_id)
-                .unwrap();
+            let (idx, (_local_id, data)) =
+                self.params.iter().enumerate().find(|(_, (idx, _))| *idx == param.local_id)?;
             let parent_len = self.parent_generics().map_or(0, Generics::len);
             Some((parent_len + idx, data))
         } else {