Make TraitEnvironment's constructor private

crates/hir-ty/src/consteval.rs

@@ -137,7 +137,7 @@ pub fn intern_const_ref(
     ty: Ty,
     krate: CrateId,
 ) -> Const {
-    let layout = db.layout_of_ty(ty.clone(), Arc::new(TraitEnvironment::empty(krate)));
+    let layout = db.layout_of_ty(ty.clone(), TraitEnvironment::empty(krate));
     let bytes = match value {
         LiteralConstRef::Int(i) => {
             // FIXME: We should handle failure of layout better.

crates/hir-ty/src/display.rs

@@ -448,9 +448,8 @@ fn render_const_scalar(
 ) -> Result<(), HirDisplayError> {
     // FIXME: We need to get krate from the final callers of the hir display
     // infrastructure and have it here as a field on `f`.
-    let trait_env = Arc::new(TraitEnvironment::empty(
+    let trait_env =
-        *f.db.crate_graph().crates_in_topological_order().last().unwrap(),
+        TraitEnvironment::empty(*f.db.crate_graph().crates_in_topological_order().last().unwrap());
-    ));
     match ty.kind(Interner) {
         TyKind::Scalar(s) => match s {
             Scalar::Bool => write!(f, "{}", if b[0] == 0 { false } else { true }),

crates/hir-ty/src/infer/expr.rs

@@ -18,7 +18,6 @@ use hir_def::{
 use hir_expand::name::{name, Name};
 use stdx::always;
 use syntax::ast::RangeOp;
-use triomphe::Arc;
 
 use crate::{
     autoderef::{builtin_deref, deref_by_trait, Autoderef},
@@ -40,7 +39,8 @@ use crate::{
     traits::FnTrait,
     utils::{generics, Generics},
     Adjust, Adjustment, AdtId, AutoBorrow, Binders, CallableDefId, FnPointer, FnSig, FnSubst,
-    Interner, Rawness, Scalar, Substitution, TraitRef, Ty, TyBuilder, TyExt, TyKind,
+    Interner, Rawness, Scalar, Substitution, TraitEnvironment, TraitRef, Ty, TyBuilder, TyExt,
+    TyKind,
 };
 
 use super::{
@@ -1291,7 +1291,7 @@ impl InferenceContext<'_> {
         let g = self.resolver.update_to_inner_scope(self.db.upcast(), self.owner, expr);
         let prev_env = block_id.map(|block_id| {
             let prev_env = self.table.trait_env.clone();
-            Arc::make_mut(&mut self.table.trait_env).block = Some(block_id);
+            TraitEnvironment::with_block(&mut self.table.trait_env, block_id);
             prev_env
         });
 

crates/hir-ty/src/lib.rs

@@ -122,7 +122,7 @@ pub type TyKind = chalk_ir::TyKind<Interner>;
 pub type TypeFlags = chalk_ir::TypeFlags;
 pub type DynTy = chalk_ir::DynTy<Interner>;
 pub type FnPointer = chalk_ir::FnPointer<Interner>;
-// pub type FnSubst = chalk_ir::FnSubst<Interner>;
+// pub type FnSubst = chalk_ir::FnSubst<Interner>; // a re-export so we don't lose the tuple constructor
 pub use chalk_ir::FnSubst;
 pub type ProjectionTy = chalk_ir::ProjectionTy<Interner>;
 pub type AliasTy = chalk_ir::AliasTy<Interner>;

crates/hir-ty/src/lower.rs

@@ -1468,7 +1468,7 @@ pub(crate) fn trait_environment_for_body_query(
 ) -> Arc<TraitEnvironment> {
     let Some(def) = def.as_generic_def_id() else {
         let krate = def.module(db.upcast()).krate();
-        return Arc::new(TraitEnvironment::empty(krate));
+        return TraitEnvironment::empty(krate);
     };
     db.trait_environment(def)
 }
@@ -1528,12 +1528,7 @@ pub(crate) fn trait_environment_query(
 
     let env = chalk_ir::Environment::new(Interner).add_clauses(Interner, clauses);
 
-    Arc::new(TraitEnvironment {
+    TraitEnvironment::new(krate, None, traits_in_scope.into_boxed_slice(), env)
-        krate,
-        block: None,
-        traits_from_clauses: traits_in_scope.into_boxed_slice(),
-        env,
-    })
 }
 
 /// Resolve the where clause(s) of an item with generics.

crates/hir-ty/src/mir.rs

@@ -40,7 +40,6 @@ pub use monomorphization::{
 use rustc_hash::FxHashMap;
 use smallvec::{smallvec, SmallVec};
 use stdx::{impl_from, never};
-use triomphe::Arc;
 
 use super::consteval::{intern_const_scalar, try_const_usize};
 
@@ -147,7 +146,7 @@ impl<V, T> ProjectionElem<V, T> {
             base = normalize(
                 db,
                 // FIXME: we should get this from caller
-                Arc::new(TraitEnvironment::empty(krate)),
+                TraitEnvironment::empty(krate),
                 base,
             );
         }

crates/hir-ty/src/traits.rs

@@ -48,18 +48,32 @@ pub struct TraitEnvironment {
     pub krate: CrateId,
     pub block: Option<BlockId>,
     // FIXME make this a BTreeMap
-    pub(crate) traits_from_clauses: Box<[(Ty, TraitId)]>,
+    traits_from_clauses: Box<[(Ty, TraitId)]>,
     pub env: chalk_ir::Environment<Interner>,
 }
 
 impl TraitEnvironment {
-    pub fn empty(krate: CrateId) -> Self {
+    pub fn empty(krate: CrateId) -> Arc<Self> {
-        TraitEnvironment {
+        Arc::new(TraitEnvironment {
             krate,
             block: None,
             traits_from_clauses: Box::default(),
             env: chalk_ir::Environment::new(Interner),
+        })
     }
+
+    pub fn new(
+        krate: CrateId,
+        block: Option<BlockId>,
+        traits_from_clauses: Box<[(Ty, TraitId)]>,
+        env: chalk_ir::Environment<Interner>,
+    ) -> Arc<Self> {
+        Arc::new(TraitEnvironment { krate, block, traits_from_clauses, env })
+    }
+
+    // pub fn with_block(self: &mut Arc<Self>, block: BlockId) {
+    pub fn with_block(this: &mut Arc<Self>, block: BlockId) {
+        Arc::make_mut(this).block = Some(block);
     }
 
     pub fn traits_in_scope_from_clauses(&self, ty: Ty) -> impl Iterator<Item = TraitId> + '_ {

crates/hir/src/lib.rs

@@ -3564,10 +3564,9 @@ impl TraitRef {
         resolver: &Resolver,
         trait_ref: hir_ty::TraitRef,
     ) -> TraitRef {
-        let env = resolver.generic_def().map_or_else(
+        let env = resolver
-            || Arc::new(TraitEnvironment::empty(resolver.krate())),
+            .generic_def()
-            |d| db.trait_environment(d),
+            .map_or_else(|| TraitEnvironment::empty(resolver.krate()), |d| db.trait_environment(d));
-        );
         TraitRef { env, trait_ref }
     }
 
@@ -3707,15 +3706,14 @@ impl Type {
         resolver: &Resolver,
         ty: Ty,
     ) -> Type {
-        let environment = resolver.generic_def().map_or_else(
+        let environment = resolver
-            || Arc::new(TraitEnvironment::empty(resolver.krate())),
+            .generic_def()
-            |d| db.trait_environment(d),
+            .map_or_else(|| TraitEnvironment::empty(resolver.krate()), |d| db.trait_environment(d));
-        );
         Type { env: environment, ty }
     }
 
     pub(crate) fn new_for_crate(krate: CrateId, ty: Ty) -> Type {
-        Type { env: Arc::new(TraitEnvironment::empty(krate)), ty }
+        Type { env: TraitEnvironment::empty(krate), ty }
     }
 
     pub fn reference(inner: &Type, m: Mutability) -> Type {
@@ -3731,10 +3729,9 @@ impl Type {
 
     fn new(db: &dyn HirDatabase, lexical_env: impl HasResolver, ty: Ty) -> Type {
         let resolver = lexical_env.resolver(db.upcast());
-        let environment = resolver.generic_def().map_or_else(
+        let environment = resolver
-            || Arc::new(TraitEnvironment::empty(resolver.krate())),
+            .generic_def()
-            |d| db.trait_environment(d),
+            .map_or_else(|| TraitEnvironment::empty(resolver.krate()), |d| db.trait_environment(d));
-        );
         Type { env: environment, ty }
     }
 
@@ -4304,10 +4301,10 @@ impl Type {
         let canonical = hir_ty::replace_errors_with_variables(&self.ty);
 
         let krate = scope.krate();
-        let environment = scope.resolver().generic_def().map_or_else(
+        let environment = scope
-            || Arc::new(TraitEnvironment::empty(krate.id)),
+            .resolver()
-            |d| db.trait_environment(d),
+            .generic_def()
-        );
+            .map_or_else(|| TraitEnvironment::empty(krate.id), |d| db.trait_environment(d));
 
         method_resolution::iterate_method_candidates_dyn(
             &canonical,
@@ -4361,10 +4358,10 @@ impl Type {
         let canonical = hir_ty::replace_errors_with_variables(&self.ty);
 
         let krate = scope.krate();
-        let environment = scope.resolver().generic_def().map_or_else(
+        let environment = scope
-            || Arc::new(TraitEnvironment::empty(krate.id)),
+            .resolver()
-            |d| db.trait_environment(d),
+            .generic_def()
-        );
+            .map_or_else(|| TraitEnvironment::empty(krate.id), |d| db.trait_environment(d));
 
         method_resolution::iterate_path_candidates(
             &canonical,