1 files changed, 20 insertions, 8 deletions

diff --git a/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs b/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
index 6f2f70dd40a..96431ba4ce9 100644
--- a/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
+++ b/src/tools/rust-analyzer/crates/hir-ty/src/infer.rs
@@ -49,6 +49,7 @@ use hir_def::{
 use hir_expand::name::{name, Name};
 use indexmap::IndexSet;
 use la_arena::{ArenaMap, Entry};
+use once_cell::unsync::OnceCell;
 use rustc_hash::{FxHashMap, FxHashSet};
 use stdx::{always, never};
 use triomphe::Arc;
@@ -56,14 +57,15 @@ use triomphe::Arc;
 use crate::{
     db::HirDatabase,
     error_lifetime, fold_tys,
+    generics::Generics,
     infer::{coerce::CoerceMany, unify::InferenceTable},
     lower::ImplTraitLoweringMode,
     to_assoc_type_id,
     traits::FnTrait,
-    utils::{Generics, InTypeConstIdMetadata, UnevaluatedConstEvaluatorFolder},
+    utils::{InTypeConstIdMetadata, UnevaluatedConstEvaluatorFolder},
     AliasEq, AliasTy, Binders, ClosureId, Const, DomainGoal, GenericArg, Goal, ImplTraitId,
-    ImplTraitIdx, InEnvironment, Interner, Lifetime, OpaqueTyId, ProjectionTy, Substitution,
-    TraitEnvironment, Ty, TyBuilder, TyExt,
+    ImplTraitIdx, InEnvironment, Interner, Lifetime, OpaqueTyId, ParamLoweringMode, ProjectionTy,
+    Substitution, TraitEnvironment, Ty, TyBuilder, TyExt,
 };
 
 // This lint has a false positive here. See the link below for details.
@@ -79,7 +81,7 @@ pub(crate) use closure::{CaptureKind, CapturedItem, CapturedItemWithoutTy};
 
 /// The entry point of type inference.
 pub(crate) fn infer_query(db: &dyn HirDatabase, def: DefWithBodyId) -> Arc<InferenceResult> {
-    let _p = tracing::span!(tracing::Level::INFO, "infer_query").entered();
+    let _p = tracing::info_span!("infer_query").entered();
     let resolver = def.resolver(db.upcast());
     let body = db.body(def);
     let mut ctx = InferenceContext::new(db, def, &body, resolver);
@@ -526,6 +528,7 @@ pub(crate) struct InferenceContext<'a> {
     pub(crate) owner: DefWithBodyId,
     pub(crate) body: &'a Body,
     pub(crate) resolver: Resolver,
+    generics: OnceCell<Option<Generics>>,
     table: unify::InferenceTable<'a>,
     /// The traits in scope, disregarding block modules. This is used for caching purposes.
     traits_in_scope: FxHashSet<TraitId>,
@@ -611,6 +614,7 @@ impl<'a> InferenceContext<'a> {
     ) -> Self {
         let trait_env = db.trait_environment_for_body(owner);
         InferenceContext {
+            generics: OnceCell::new(),
             result: InferenceResult::default(),
             table: unify::InferenceTable::new(db, trait_env),
             tuple_field_accesses_rev: Default::default(),
@@ -632,8 +636,14 @@ impl<'a> InferenceContext<'a> {
         }
     }
 
-    pub(crate) fn generics(&self) -> Option<Generics> {
-        Some(crate::utils::generics(self.db.upcast(), self.resolver.generic_def()?))
+    pub(crate) fn generics(&self) -> Option<&Generics> {
+        self.generics
+            .get_or_init(|| {
+                self.resolver
+                    .generic_def()
+                    .map(|def| crate::generics::generics(self.db.upcast(), def))
+            })
+            .as_ref()
     }
 
     // FIXME: This function should be private in module. It is currently only used in the consteval, since we need
@@ -781,7 +791,8 @@ impl<'a> InferenceContext<'a> {
 
     fn collect_fn(&mut self, func: FunctionId) {
         let data = self.db.function_data(func);
-        let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver, func.into())
+        let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver, self.owner.into())
+            .with_type_param_mode(ParamLoweringMode::Placeholder)
             .with_impl_trait_mode(ImplTraitLoweringMode::Param);
         let mut param_tys =
             data.params.iter().map(|type_ref| ctx.lower_ty(type_ref)).collect::<Vec<_>>();
@@ -816,6 +827,7 @@ impl<'a> InferenceContext<'a> {
         let return_ty = &*data.ret_type;
 
         let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver, self.owner.into())
+            .with_type_param_mode(ParamLoweringMode::Placeholder)
             .with_impl_trait_mode(ImplTraitLoweringMode::Opaque);
         let return_ty = ctx.lower_ty(return_ty);
         let return_ty = self.insert_type_vars(return_ty);
@@ -1263,7 +1275,7 @@ impl<'a> InferenceContext<'a> {
                 forbid_unresolved_segments((ty, Some(var.into())), unresolved)
             }
             TypeNs::SelfType(impl_id) => {
-                let generics = crate::utils::generics(self.db.upcast(), impl_id.into());
+                let generics = crate::generics::generics(self.db.upcast(), impl_id.into());
                 let substs = generics.placeholder_subst(self.db);
                 let mut ty = self.db.impl_self_ty(impl_id).substitute(Interner, &substs);