⬆️ rust-analyzer

crates/hir-ty/src/lower.rs

@@ -6,7 +6,7 @@
 //!
 //! This usually involves resolving names, collecting generic arguments etc.
 use std::{
-    cell::{Cell, RefCell},
+    cell::{Cell, RefCell, RefMut},
     iter,
     sync::Arc,
 };
@@ -330,26 +330,26 @@ impl<'a> TyLoweringContext<'a> {
                 }
             }
             TypeRef::Macro(macro_call) => {
-                let (expander, recursion_start) = {
-                    let mut expander = self.expander.borrow_mut();
-                    if expander.is_some() {
-                        (Some(expander), false)
-                    } else {
-                        *expander = Some(Expander::new(
-                            self.db.upcast(),
-                            macro_call.file_id,
-                            self.resolver.module(),
-                        ));
-                        (Some(expander), true)
+                let (mut expander, recursion_start) = {
+                    match RefMut::filter_map(self.expander.borrow_mut(), Option::as_mut) {
+                        Ok(expander) => (expander, false),
+                        Err(expander) => (
+                            RefMut::map(expander, |it| {
+                                it.insert(Expander::new(
+                                    self.db.upcast(),
+                                    macro_call.file_id,
+                                    self.resolver.module(),
+                                ))
+                            }),
+                            true,
+                        ),
                     }
                 };
-                let ty = if let Some(mut expander) = expander {
-                    let expander_mut = expander.as_mut().unwrap();
+                let ty = {
                     let macro_call = macro_call.to_node(self.db.upcast());
-                    match expander_mut.enter_expand::<ast::Type>(self.db.upcast(), macro_call) {
+                    match expander.enter_expand::<ast::Type>(self.db.upcast(), macro_call) {
                         Ok(ExpandResult { value: Some((mark, expanded)), .. }) => {
-                            let ctx =
-                                LowerCtx::new(self.db.upcast(), expander_mut.current_file_id());
+                            let ctx = LowerCtx::new(self.db.upcast(), expander.current_file_id());
                             let type_ref = TypeRef::from_ast(&ctx, expanded);
 
                             drop(expander);
@@ -364,8 +364,6 @@ impl<'a> TyLoweringContext<'a> {
                         }
                         _ => None,
                     }
-                } else {
-                    None
                 };
                 if recursion_start {
                     *self.expander.borrow_mut() = None;
@@ -479,7 +477,14 @@ impl<'a> TyLoweringContext<'a> {
                         TyKind::Placeholder(to_placeholder_idx(self.db, param_id.into()))
                     }
                     ParamLoweringMode::Variable => {
-                        let idx = generics.param_idx(param_id.into()).expect("matching generics");
+                        let idx = match generics.param_idx(param_id.into()) {
+                            None => {
+                                never!("no matching generics");
+                                return (TyKind::Error.intern(Interner), None);
+                            }
+                            Some(idx) => idx,
+                        };
+
                         TyKind::BoundVar(BoundVar::new(self.in_binders, idx))
                     }
                 }

crates/hir-ty/src/test_db.rs

@@ -10,7 +10,7 @@ use base_db::{
 };
 use hir_def::{db::DefDatabase, ModuleId};
 use hir_expand::db::AstDatabase;
-use rustc_hash::{FxHashMap, FxHashSet};
+use stdx::hash::{NoHashHashMap, NoHashHashSet};
 use syntax::TextRange;
 use test_utils::extract_annotations;
 
@@ -80,7 +80,7 @@ impl FileLoader for TestDB {
     fn resolve_path(&self, path: AnchoredPath<'_>) -> Option<FileId> {
         FileLoaderDelegate(self).resolve_path(path)
     }
-    fn relevant_crates(&self, file_id: FileId) -> Arc<FxHashSet<CrateId>> {
+    fn relevant_crates(&self, file_id: FileId) -> Arc<NoHashHashSet<CrateId>> {
         FileLoaderDelegate(self).relevant_crates(file_id)
     }
 }
@@ -102,7 +102,7 @@ impl TestDB {
         self.module_for_file_opt(file_id).unwrap()
     }
 
-    pub(crate) fn extract_annotations(&self) -> FxHashMap<FileId, Vec<(TextRange, String)>> {
+    pub(crate) fn extract_annotations(&self) -> NoHashHashMap<FileId, Vec<(TextRange, String)>> {
         let mut files = Vec::new();
         let crate_graph = self.crate_graph();
         for krate in crate_graph.iter() {

crates/hir-ty/src/tests/regression.rs

@@ -1526,6 +1526,34 @@ unsafe impl Storage for InlineStorage {
     );
 }
 
+#[test]
+fn gat_crash_3() {
+    // FIXME: This test currently crashes rust analyzer in a debug build but not in a
+    // release build (i.e. for the user). With the assumption that tests will always be run
+    // in debug mode, we catch the unwind and expect that it panicked. See the
+    // [`crate::utils::generics`] function for more information.
+    cov_mark::check!(ignore_gats);
+    std::panic::catch_unwind(|| {
+        check_no_mismatches(
+            r#"
+trait Collection {
+    type Item;
+    type Member<T>: Collection<Item = T>;
+    fn add(&mut self, value: Self::Item) -> Result<(), Self::Error>;
+}
+struct ConstGen<T, const N: usize> {
+    data: [T; N],
+}
+impl<T, const N: usize> Collection for ConstGen<T, N> {
+    type Item = T;
+    type Member<U> = ConstGen<U, N>;
+}
+        "#,
+        );
+    })
+    .expect_err("must panic");
+}
+
 #[test]
 fn cfgd_out_self_param() {
     cov_mark::check!(cfgd_out_self_param);

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 @@ impl Generics {
 
     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 {