Remove Resolver from autoderef

Resolver holds onto too much context, including local scopes. Let's
try to pass in only what is necessary -- the trait environment.

7 files changed, 73 insertions, 49 deletions

diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 31390bb7f..b4f0e81d3 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -26,7 +26,10 @@ use ra_syntax::{
 use crate::{
     db::HirDatabase,
     expr::{BodySourceMap, ExprScopes, ScopeId},
-    ty::method_resolution::{self, implements_trait},
+    ty::{
+        method_resolution::{self, implements_trait},
+        TraitEnvironment,
+    },
     Adt, AssocItem, Const, DefWithBody, Either, Enum, EnumVariant, FromSource, Function,
     GenericParam, Local, MacroDef, Name, Path, ScopeDef, Static, Struct, Trait, Ty, TypeAlias,
 };
@@ -408,7 +411,10 @@ impl SourceAnalyzer {
         // There should be no inference vars in types passed here
         // FIXME check that?
         let canonical = crate::ty::Canonical { value: ty, num_vars: 0 };
-        crate::ty::autoderef(db, &self.resolver, canonical).map(|canonical| canonical.value)
+        let krate = self.resolver.krate();
+        let environment = TraitEnvironment::lower(db, &self.resolver);
+        let ty = crate::ty::InEnvironment { value: canonical, environment };
+        crate::ty::autoderef(db, krate, ty).map(|canonical| canonical.value)
     }
 
     /// Checks that particular type `ty` implements `std::future::Future`.
diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index 86b08ae6f..44547197c 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -5,7 +5,7 @@
 
 use std::iter::successors;
 
-use hir_def::{lang_item::LangItemTarget, resolver::Resolver};
+use hir_def::lang_item::LangItemTarget;
 use hir_expand::name;
 use log::{info, warn};
 use ra_db::CrateId;
@@ -21,23 +21,25 @@ const AUTODEREF_RECURSION_LIMIT: usize = 10;
 
 pub(crate) fn autoderef<'a>(
     db: &'a impl HirDatabase,
-    resolver: &'a Resolver,
-    ty: Canonical<Ty>,
+    krate: Option<CrateId>,
+    ty: InEnvironment<Canonical<Ty>>,
 ) -> impl Iterator<Item = Canonical<Ty>> + 'a {
-    successors(Some(ty), move |ty| deref(db, resolver, ty)).take(AUTODEREF_RECURSION_LIMIT)
+    let InEnvironment { value: ty, environment } = ty;
+    successors(Some(ty), move |ty| {
+        deref(db, krate?, InEnvironment { value: ty, environment: environment.clone() })
+    })
+    .take(AUTODEREF_RECURSION_LIMIT)
 }
 
 pub(crate) fn deref(
     db: &impl HirDatabase,
-    resolver: &Resolver,
-    ty: &Canonical<Ty>,
+    krate: CrateId,
+    ty: InEnvironment<&Canonical<Ty>>,
 ) -> Option<Canonical<Ty>> {
-    if let Some(derefed) = ty.value.builtin_deref() {
-        Some(Canonical { value: derefed, num_vars: ty.num_vars })
+    if let Some(derefed) = ty.value.value.builtin_deref() {
+        Some(Canonical { value: derefed, num_vars: ty.value.num_vars })
     } else {
-        let krate = resolver.krate()?;
-        let environment = super::lower::trait_env(db, resolver);
-        deref_by_trait(db, krate, InEnvironment { value: ty, environment })
+        deref_by_trait(db, krate, ty)
     }
 }
 
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index ddc7d262a..6fd00d457 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -34,7 +34,6 @@ use ra_prof::profile;
 use test_utils::tested_by;
 
 use super::{
-    lower,
     traits::{Guidance, Obligation, ProjectionPredicate, Solution},
     ApplicationTy, InEnvironment, ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypableDef,
     TypeCtor, TypeWalk, Uncertain,
@@ -216,7 +215,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             var_unification_table: InPlaceUnificationTable::new(),
             obligations: Vec::default(),
             return_ty: Ty::Unknown, // set in collect_fn_signature
-            trait_env: lower::trait_env(db, &resolver),
+            trait_env: TraitEnvironment::lower(db, &resolver),
             coerce_unsized_map: Self::init_coerce_unsized_map(db, &resolver),
             db,
             owner,
diff --git a/crates/ra_hir/src/ty/infer/coerce.rs b/crates/ra_hir/src/ty/infer/coerce.rs
index 54765da35..4b53bba73 100644
--- a/crates/ra_hir/src/ty/infer/coerce.rs
+++ b/crates/ra_hir/src/ty/infer/coerce.rs
@@ -14,7 +14,7 @@ use crate::{
     Adt, Mutability,
 };
 
-use super::{InferTy, InferenceContext, TypeVarValue};
+use super::{InEnvironment, InferTy, InferenceContext, TypeVarValue};
 
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     /// Unify two types, but may coerce the first one to the second one
@@ -320,9 +320,14 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let canonicalized = self.canonicalizer().canonicalize_ty(from_ty.clone());
         let to_ty = self.resolve_ty_shallow(&to_ty);
         // FIXME: Auto DerefMut
-        for derefed_ty in
-            autoderef::autoderef(self.db, &self.resolver.clone(), canonicalized.value.clone())
-        {
+        for derefed_ty in autoderef::autoderef(
+            self.db,
+            self.resolver.krate(),
+            InEnvironment {
+                value: canonicalized.value.clone(),
+                environment: self.trait_env.clone(),
+            },
+        ) {
             let derefed_ty = canonicalized.decanonicalize_ty(derefed_ty.value);
             match (&*self.resolve_ty_shallow(&derefed_ty), &*to_ty) {
                 // Stop when constructor matches.
diff --git a/crates/ra_hir/src/ty/infer/expr.rs b/crates/ra_hir/src/ty/infer/expr.rs
index 663ff9435..194e55819 100644
--- a/crates/ra_hir/src/ty/infer/expr.rs
+++ b/crates/ra_hir/src/ty/infer/expr.rs
@@ -15,9 +15,9 @@ use crate::{
     db::HirDatabase,
     expr::{Array, BinaryOp, Expr, ExprId, Literal, Statement, UnaryOp},
     ty::{
-        autoderef, method_resolution, op, CallableDef, InferTy, IntTy, Mutability, Namespace,
-        Obligation, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor, TypeWalk,
-        Uncertain,
+        autoderef, method_resolution, op, traits::InEnvironment, CallableDef, InferTy, IntTy,
+        Mutability, Namespace, Obligation, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty,
+        TypeCtor, TypeWalk, Uncertain,
     },
     Adt, Name,
 };
@@ -245,8 +245,11 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
                 let canonicalized = self.canonicalizer().canonicalize_ty(receiver_ty);
                 let ty = autoderef::autoderef(
                     self.db,
-                    &self.resolver.clone(),
-                    canonicalized.value.clone(),
+                    self.resolver.krate(),
+                    InEnvironment {
+                        value: canonicalized.value.clone(),
+                        environment: self.trait_env.clone(),
+                    },
                 )
                 .find_map(|derefed_ty| match canonicalized.decanonicalize_ty(derefed_ty.value) {
                     Ty::Apply(a_ty) => match a_ty.ctor {
@@ -337,16 +340,25 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             Expr::UnaryOp { expr, op } => {
                 let inner_ty = self.infer_expr(*expr, &Expectation::none());
                 match op {
-                    UnaryOp::Deref => {
-                        let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
-                        if let Some(derefed_ty) =
-                            autoderef::deref(self.db, &self.resolver, &canonicalized.value)
-                        {
-                            canonicalized.decanonicalize_ty(derefed_ty.value)
-                        } else {
-                            Ty::Unknown
+                    UnaryOp::Deref => match self.resolver.krate() {
+                        Some(krate) => {
+                            let canonicalized = self.canonicalizer().canonicalize_ty(inner_ty);
+                            match autoderef::deref(
+                                self.db,
+                                krate,
+                                InEnvironment {
+                                    value: &canonicalized.value,
+                                    environment: self.trait_env.clone(),
+                                },
+                            ) {
+                                Some(derefed_ty) => {
+                                    canonicalized.decanonicalize_ty(derefed_ty.value)
+                                }
+                                None => Ty::Unknown,
+                            }
                         }
-                    }
+                        None => Ty::Unknown,
+                    },
                     UnaryOp::Neg => {
                         match &inner_ty {
                             Ty::Apply(a_ty) => match a_ty.ctor {
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index a39beb2a0..b76929501 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -19,8 +19,8 @@ use hir_def::{
 use ra_arena::map::ArenaMap;
 
 use super::{
-    FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty, TypeCtor,
-    TypeWalk,
+    FnSig, GenericPredicate, ProjectionPredicate, ProjectionTy, Substs, TraitEnvironment, TraitRef,
+    Ty, TypeCtor, TypeWalk,
 };
 use crate::{
     db::HirDatabase,
@@ -591,16 +591,15 @@ pub(crate) fn generic_predicates_for_param_query(
         .collect()
 }
 
-pub(crate) fn trait_env(
-    db: &impl HirDatabase,
-    resolver: &Resolver,
-) -> Arc<super::TraitEnvironment> {
-    let predicates = resolver
-        .where_predicates_in_scope()
-        .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
-        .collect::<Vec<_>>();
+impl TraitEnvironment {
+    pub(crate) fn lower(db: &impl HirDatabase, resolver: &Resolver) -> Arc<TraitEnvironment> {
+        let predicates = resolver
+            .where_predicates_in_scope()
+            .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
+            .collect::<Vec<_>>();
 
-    Arc::new(super::TraitEnvironment { predicates })
+        Arc::new(TraitEnvironment { predicates })
+    }
 }
 
 /// Resolve the where clause(s) of an item with generics.
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index caa5f5f74..f7905b5ff 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -15,7 +15,7 @@ use crate::{
     AssocItem, Crate, Function, ImplBlock, Module, Mutability, Name, Trait,
 };
 
-use super::{autoderef, lower, Canonical, InEnvironment, TraitEnvironment, TraitRef};
+use super::{autoderef, Canonical, InEnvironment, TraitEnvironment, TraitRef};
 
 /// This is used as a key for indexing impls.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
@@ -179,8 +179,9 @@ pub(crate) fn iterate_method_candidates<T>(
             // Also note that when we've got a receiver like &S, even if the method we
             // find in the end takes &self, we still do the autoderef step (just as
             // rustc does an autoderef and then autoref again).
-
-            for derefed_ty in autoderef::autoderef(db, resolver, ty.clone()) {
+            let environment = TraitEnvironment::lower(db, resolver);
+            let ty = InEnvironment { value: ty.clone(), environment };
+            for derefed_ty in autoderef::autoderef(db, resolver.krate(), ty) {
                 if let Some(result) = iterate_inherent_methods(
                     &derefed_ty,
                     db,
@@ -230,7 +231,7 @@ fn iterate_trait_method_candidates<T>(
 ) -> Option<T> {
     let krate = resolver.krate()?;
     // FIXME: maybe put the trait_env behind a query (need to figure out good input parameters for that)
-    let env = lower::trait_env(db, resolver);
+    let env = TraitEnvironment::lower(db, resolver);
     // if ty is `impl Trait` or `dyn Trait`, the trait doesn't need to be in scope
     let inherent_trait = ty.value.inherent_trait().into_iter();
     // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
@@ -324,7 +325,7 @@ pub(crate) fn implements_trait(
         // anyway, but currently Chalk doesn't implement `dyn/impl Trait` yet
         return true;
     }
-    let env = lower::trait_env(db, resolver);
+    let env = TraitEnvironment::lower(db, resolver);
     let goal = generic_implements_goal(db, env, trait_, ty.clone());
     let solution = db.trait_solve(krate, goal);