15 files changed, 55 insertions, 65 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 965d5aaa0..0826b056a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -891,17 +891,14 @@ version = "0.1.0"
 name = "ra_assists"
 version = "0.1.0"
 dependencies = [
- "arrayvec 0.4.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "format-buf 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "join_to_string 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
- "once_cell 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_db 0.1.0",
  "ra_fmt 0.1.0",
  "ra_hir 0.1.0",
  "ra_syntax 0.1.0",
  "ra_text_edit 0.1.0",
- "rustc-hash 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc_lexer 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "test_utils 0.1.0",
 ]
@@ -1031,8 +1028,6 @@ dependencies = [
  "lsp-server 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lsp-types 0.61.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "parking_lot 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "ra_cfg 0.1.0",
- "ra_db 0.1.0",
  "ra_ide_api 0.1.0",
  "ra_prof 0.1.0",
  "ra_project_model 0.1.0",
@@ -1053,7 +1048,6 @@ dependencies = [
 name = "ra_mbe"
 version = "0.1.0"
 dependencies = [
- "itertools 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
  "ra_parser 0.1.0",
  "ra_syntax 0.1.0",
diff --git a/crates/ra_assists/Cargo.toml b/crates/ra_assists/Cargo.toml
index d3b6aeb36..beebccbd9 100644
--- a/crates/ra_assists/Cargo.toml
+++ b/crates/ra_assists/Cargo.toml
@@ -6,11 +6,8 @@ authors = ["rust-analyzer developers"]
 
 [dependencies]
 format-buf = "1.0.0"
-once_cell = "1.0.1"
 join_to_string = "0.1.3"
 itertools = "0.8.0"
-arrayvec = "0.4.10"
-rustc-hash = "1.0.1"
 rustc_lexer = "0.1.0"
 
 ra_syntax = { path = "../ra_syntax" }
diff --git a/crates/ra_assists/src/assists/move_bounds.rs b/crates/ra_assists/src/assists/move_bounds.rs
index f791d22b0..d2444b6b9 100644
--- a/crates/ra_assists/src/assists/move_bounds.rs
+++ b/crates/ra_assists/src/assists/move_bounds.rs
@@ -18,7 +18,7 @@ pub(crate) fn move_bounds_to_where_clause(mut ctx: AssistCtx<impl HirDatabase>)
     }
 
     let parent = type_param_list.syntax().parent()?;
-    if parent.children_with_tokens().find(|it| it.kind() == WHERE_CLAUSE).is_some() {
+    if parent.children_with_tokens().any(|it| it.kind() == WHERE_CLAUSE) {
         return None;
     }
 
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 9cbd9a8ae..ca261e8f5 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -51,6 +51,7 @@ mod lang_item;
 mod generics;
 mod resolve;
 pub mod diagnostics;
+mod util;
 
 mod code_model;
 
diff --git a/crates/ra_hir/src/ty.rs b/crates/ra_hir/src/ty.rs
index d161735e8..cc9746f6d 100644
--- a/crates/ra_hir/src/ty.rs
+++ b/crates/ra_hir/src/ty.rs
@@ -17,8 +17,8 @@ use std::sync::Arc;
 use std::{fmt, iter, mem};
 
 use crate::{
-    db::HirDatabase, expr::ExprId, type_ref::Mutability, Adt, Crate, DefWithBody, GenericParams,
-    HasGenericParams, Name, Trait, TypeAlias,
+    db::HirDatabase, expr::ExprId, type_ref::Mutability, util::make_mut_slice, Adt, Crate,
+    DefWithBody, GenericParams, HasGenericParams, Name, Trait, TypeAlias,
 };
 use display::{HirDisplay, HirFormatter};
 
@@ -308,12 +308,9 @@ impl Substs {
     }
 
     pub fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
-        // Without an Arc::make_mut_slice, we can't avoid the clone here:
-        let mut v: Vec<_> = self.0.iter().cloned().collect();
-        for t in &mut v {
+        for t in make_mut_slice(&mut self.0) {
             t.walk_mut(f);
         }
-        self.0 = v.into();
     }
 
     pub fn as_single(&self) -> &Ty {
@@ -330,8 +327,7 @@ impl Substs {
                 .params_including_parent()
                 .into_iter()
                 .map(|p| Ty::Param { idx: p.idx, name: p.name.clone() })
-                .collect::<Vec<_>>()
-                .into(),
+                .collect(),
         )
     }
 
@@ -342,8 +338,7 @@ impl Substs {
                 .params_including_parent()
                 .into_iter()
                 .map(|p| Ty::Bound(p.idx))
-                .collect::<Vec<_>>()
-                .into(),
+                .collect(),
         )
     }
 
@@ -541,12 +536,9 @@ impl TypeWalk for FnSig {
     }
 
     fn walk_mut(&mut self, f: &mut impl FnMut(&mut Ty)) {
-        // Without an Arc::make_mut_slice, we can't avoid the clone here:
-        let mut v: Vec<_> = self.params_and_return.iter().cloned().collect();
-        for t in &mut v {
+        for t in make_mut_slice(&mut self.params_and_return) {
             t.walk_mut(f);
         }
-        self.params_and_return = v.into();
     }
 }
 
@@ -756,11 +748,9 @@ impl TypeWalk for Ty {
                 p_ty.parameters.walk_mut(f);
             }
             Ty::Dyn(predicates) | Ty::Opaque(predicates) => {
-                let mut v: Vec<_> = predicates.iter().cloned().collect();
-                for p in &mut v {
+                for p in make_mut_slice(predicates) {
                     p.walk_mut(f);
                 }
-                *predicates = v.into();
             }
             Ty::Param { .. } | Ty::Bound(_) | Ty::Infer(_) | Ty::Unknown => {}
         }
diff --git a/crates/ra_hir/src/ty/infer/unify.rs b/crates/ra_hir/src/ty/infer/unify.rs
index d161aa6b3..014c7981f 100644
--- a/crates/ra_hir/src/ty/infer/unify.rs
+++ b/crates/ra_hir/src/ty/infer/unify.rs
@@ -6,6 +6,7 @@ use crate::ty::{
     Canonical, InEnvironment, InferTy, ProjectionPredicate, ProjectionTy, Substs, TraitRef, Ty,
     TypeWalk,
 };
+use crate::util::make_mut_slice;
 
 impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     pub(super) fn canonicalizer<'b>(&'b mut self) -> Canonicalizer<'a, 'b, D>
@@ -74,10 +75,11 @@ where
         })
     }
 
-    fn do_canonicalize_trait_ref(&mut self, trait_ref: TraitRef) -> TraitRef {
-        let substs =
-            trait_ref.substs.iter().map(|ty| self.do_canonicalize_ty(ty.clone())).collect();
-        TraitRef { trait_: trait_ref.trait_, substs: Substs(substs) }
+    fn do_canonicalize_trait_ref(&mut self, mut trait_ref: TraitRef) -> TraitRef {
+        for ty in make_mut_slice(&mut trait_ref.substs.0) {
+            *ty = self.do_canonicalize_ty(ty.clone());
+        }
+        trait_ref
     }
 
     fn into_canonicalized<T>(self, result: T) -> Canonicalized<T> {
@@ -87,10 +89,11 @@ where
         }
     }
 
-    fn do_canonicalize_projection_ty(&mut self, projection_ty: ProjectionTy) -> ProjectionTy {
-        let params =
-            projection_ty.parameters.iter().map(|ty| self.do_canonicalize_ty(ty.clone())).collect();
-        ProjectionTy { associated_ty: projection_ty.associated_ty, parameters: Substs(params) }
+    fn do_canonicalize_projection_ty(&mut self, mut projection_ty: ProjectionTy) -> ProjectionTy {
+        for ty in make_mut_slice(&mut projection_ty.parameters.0) {
+            *ty = self.do_canonicalize_ty(ty.clone());
+        }
+        projection_ty
     }
 
     fn do_canonicalize_projection_predicate(
diff --git a/crates/ra_hir/src/ty/lower.rs b/crates/ra_hir/src/ty/lower.rs
index a604c02e2..366556134 100644
--- a/crates/ra_hir/src/ty/lower.rs
+++ b/crates/ra_hir/src/ty/lower.rs
@@ -22,6 +22,7 @@ use crate::{
     resolve::{Resolver, TypeNs},
     ty::Adt,
     type_ref::{TypeBound, TypeRef},
+    util::make_mut_slice,
     BuiltinType, Const, Enum, EnumVariant, Function, ModuleDef, Path, Static, Struct, StructField,
     Trait, TypeAlias, Union,
 };
@@ -31,11 +32,11 @@ impl Ty {
         match type_ref {
             TypeRef::Never => Ty::simple(TypeCtor::Never),
             TypeRef::Tuple(inner) => {
-                let inner_tys =
-                    inner.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect::<Vec<_>>();
+                let inner_tys: Arc<[Ty]> =
+                    inner.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect();
                 Ty::apply(
                     TypeCtor::Tuple { cardinality: inner_tys.len() as u16 },
-                    Substs(inner_tys.into()),
+                    Substs(inner_tys),
                 )
             }
             TypeRef::Path(path) => Ty::from_hir_path(db, resolver, path),
@@ -57,9 +58,7 @@ impl Ty {
             }
             TypeRef::Placeholder => Ty::Unknown,
             TypeRef::Fn(params) => {
-                let inner_tys =
-                    params.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect::<Vec<_>>();
-                let sig = Substs(inner_tys.into());
+                let sig = Substs(params.iter().map(|tr| Ty::from_hir(db, resolver, tr)).collect());
                 Ty::apply(TypeCtor::FnPtr { num_args: sig.len() as u16 - 1 }, sig)
             }
             TypeRef::DynTrait(bounds) => {
@@ -69,8 +68,8 @@ impl Ty {
                     .flat_map(|b| {
                         GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone())
                     })
-                    .collect::<Vec<_>>();
-                Ty::Dyn(predicates.into())
+                    .collect();
+                Ty::Dyn(predicates)
             }
             TypeRef::ImplTrait(bounds) => {
                 let self_ty = Ty::Bound(0);
@@ -79,8 +78,8 @@ impl Ty {
                     .flat_map(|b| {
                         GenericPredicate::from_type_bound(db, resolver, b, self_ty.clone())
                     })
-                    .collect::<Vec<_>>();
-                Ty::Opaque(predicates.into())
+                    .collect();
+                Ty::Opaque(predicates)
             }
             TypeRef::Error => Ty::Unknown,
         }
@@ -392,10 +391,7 @@ impl TraitRef {
     ) -> Self {
         let mut substs = TraitRef::substs_from_path(db, resolver, segment, resolved);
         if let Some(self_ty) = explicit_self_ty {
-            // FIXME this could be nicer
-            let mut substs_vec = substs.0.to_vec();
-            substs_vec[0] = self_ty;
-            substs.0 = substs_vec.into();
+            make_mut_slice(&mut substs.0)[0] = self_ty;
         }
         TraitRef { trait_: resolved, substs }
     }
@@ -558,13 +554,12 @@ pub(crate) fn generic_predicates_for_param_query(
     param_idx: u32,
 ) -> Arc<[GenericPredicate]> {
     let resolver = def.resolver(db);
-    let predicates = resolver
+    resolver
         .where_predicates_in_scope()
         // we have to filter out all other predicates *first*, before attempting to lower them
         .filter(|pred| Ty::from_hir_only_param(db, &resolver, &pred.type_ref) == Some(param_idx))
         .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
-        .collect::<Vec<_>>();
-    predicates.into()
+        .collect()
 }
 
 pub(crate) fn trait_env(
@@ -585,11 +580,10 @@ pub(crate) fn generic_predicates_query(
     def: GenericDef,
 ) -> Arc<[GenericPredicate]> {
     let resolver = def.resolver(db);
-    let predicates = resolver
+    resolver
         .where_predicates_in_scope()
         .flat_map(|pred| GenericPredicate::from_where_predicate(db, &resolver, pred))
-        .collect::<Vec<_>>();
-    predicates.into()
+        .collect()
 }
 
 /// Resolve the default type params from generics
@@ -603,9 +597,9 @@ pub(crate) fn generic_defaults_query(db: &impl HirDatabase, def: GenericDef) ->
         .map(|p| {
             p.default.as_ref().map_or(Ty::Unknown, |path| Ty::from_hir_path(db, &resolver, path))
         })
-        .collect::<Vec<_>>();
+        .collect();
 
-    Substs(defaults.into())
+    Substs(defaults)
 }
 
 fn fn_sig_for_fn(db: &impl HirDatabase, def: Function) -> FnSig {
diff --git a/crates/ra_hir/src/ty/traits.rs b/crates/ra_hir/src/ty/traits.rs
index b0f67ae50..0cb5c3798 100644
--- a/crates/ra_hir/src/ty/traits.rs
+++ b/crates/ra_hir/src/ty/traits.rs
@@ -89,7 +89,7 @@ pub(crate) fn impls_for_trait_query(
     }
     let crate_impl_blocks = db.impls_in_crate(krate);
     impls.extend(crate_impl_blocks.lookup_impl_blocks_for_trait(trait_));
-    impls.into_iter().collect::<Vec<_>>().into()
+    impls.into_iter().collect()
 }
 
 /// A set of clauses that we assume to be true. E.g. if we are inside this function:
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 9168de709..00aaf65d9 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -126,8 +126,7 @@ impl ToChalk for Substs {
                 chalk_ir::Parameter(chalk_ir::ParameterKind::Ty(ty)) => from_chalk(db, ty),
                 chalk_ir::Parameter(chalk_ir::ParameterKind::Lifetime(_)) => unimplemented!(),
             })
-            .collect::<Vec<_>>()
-            .into();
+            .collect();
         Substs(tys)
     }
 }
diff --git a/crates/ra_hir/src/util.rs b/crates/ra_hir/src/util.rs
new file mode 100644
index 000000000..0095ee45d
--- /dev/null
+++ b/crates/ra_hir/src/util.rs
@@ -0,0 +1,12 @@
+//! Internal utility functions.
+
+use std::sync::Arc;
+
+/// Helper for mutating `Arc<[T]>` (i.e. `Arc::make_mut` for Arc slices).
+/// The underlying values are cloned if there are other strong references.
+pub(crate) fn make_mut_slice<T: Clone>(a: &mut Arc<[T]>) -> &mut [T] {
+    if Arc::get_mut(a).is_none() {
+        *a = a.iter().cloned().collect();
+    }
+    Arc::get_mut(a).unwrap()
+}
diff --git a/crates/ra_ide_api/src/db.rs b/crates/ra_ide_api/src/db.rs
index b9321464b..bbf04bcf7 100644
--- a/crates/ra_ide_api/src/db.rs
+++ b/crates/ra_ide_api/src/db.rs
@@ -123,7 +123,7 @@ pub(crate) trait LineIndexDatabase: ra_db::SourceDatabase + CheckCanceled {
     fn line_index(&self, file_id: FileId) -> Arc<LineIndex>;
 }
 
-fn line_index(db: &impl ra_db::SourceDatabase, file_id: FileId) -> Arc<LineIndex> {
+fn line_index(db: &impl LineIndexDatabase, file_id: FileId) -> Arc<LineIndex> {
     let text = db.file_text(file_id);
     Arc::new(LineIndex::new(&*text))
 }
diff --git a/crates/ra_lsp_server/Cargo.toml b/crates/ra_lsp_server/Cargo.toml
index aedc55a95..46a0f958c 100644
--- a/crates/ra_lsp_server/Cargo.toml
+++ b/crates/ra_lsp_server/Cargo.toml
@@ -18,8 +18,6 @@ parking_lot = "0.9.0"
 jod-thread = "0.1.0"
 ra_vfs = "0.4.0"
 ra_syntax = { path = "../ra_syntax" }
-ra_db = { path = "../ra_db" }
-ra_cfg = { path = "../ra_cfg" }
 ra_text_edit = { path = "../ra_text_edit" }
 ra_ide_api = { path = "../ra_ide_api" }
 lsp-server = "0.2.0"
diff --git a/crates/ra_mbe/Cargo.toml b/crates/ra_mbe/Cargo.toml
index b058dde91..e8ef2457b 100644
--- a/crates/ra_mbe/Cargo.toml
+++ b/crates/ra_mbe/Cargo.toml
@@ -8,7 +8,6 @@ authors = ["rust-analyzer developers"]
 ra_syntax = { path = "../ra_syntax" }
 ra_parser = { path = "../ra_parser" }
 tt = { path = "../ra_tt", package = "ra_tt" }
-itertools = "0.8.0"
 rustc-hash = "1.0.0"
 smallvec = "0.6.9"
 log = "0.4.5"
diff --git a/crates/ra_syntax/Cargo.toml b/crates/ra_syntax/Cargo.toml
index 9bc85404a..68c594202 100644
--- a/crates/ra_syntax/Cargo.toml
+++ b/crates/ra_syntax/Cargo.toml
@@ -15,6 +15,7 @@ rustc-hash = "1.0.1"
 arrayvec = "0.4.10"
 once_cell = "1.2.0"
 
+# This crate transitively depends on `smol_str` via `rowan`.
 # ideally, `serde` should be enabled by `ra_lsp_server`, but we enable it here
 # to reduce number of compilations
 smol_str = { version = "0.1.12", features = ["serde"] }
diff --git a/crates/ra_tt/Cargo.toml b/crates/ra_tt/Cargo.toml
index 3328d312f..3fcc7f085 100644
--- a/crates/ra_tt/Cargo.toml
+++ b/crates/ra_tt/Cargo.toml
@@ -5,4 +5,6 @@ version = "0.1.0"
 authors = ["rust-analyzer developers"]
 
 [dependencies]
-smol_str = "0.1.9"
+# ideally, `serde` should be enabled by `ra_lsp_server`, but we enable it here
+# to reduce number of compilations
+smol_str = { version = "0.1.12", features = ["serde"] }