24 files changed, 459 insertions, 336 deletions

diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index a7c42ca1e..ca9a7f7fa 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -513,9 +513,8 @@ impl Field {
     }
 
     /// Returns the type as in the signature of the struct (i.e., with
-    /// placeholder types for type parameters). This is good for showing
-    /// signature help, but not so good to actually get the type of the field
-    /// when you actually have a variable of the struct.
+    /// placeholder types for type parameters). Only use this in the context of
+    /// the field definition.
     pub fn ty(&self, db: &dyn HirDatabase) -> Type {
         let var_id = self.parent.into();
         let generic_def_id: GenericDefId = match self.parent {
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 1b5064b5a..3aa467e3c 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -11,7 +11,7 @@ use hir_def::{
     AsMacroCall, FunctionId, TraitId, VariantId,
 };
 use hir_expand::{name::AsName, ExpansionInfo};
-use hir_ty::associated_type_shorthand_candidates;
+use hir_ty::{associated_type_shorthand_candidates, Interner};
 use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::{
@@ -227,7 +227,7 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
     pub fn resolve_record_field(
         &self,
         field: &ast::RecordExprField,
-    ) -> Option<(Field, Option<Local>)> {
+    ) -> Option<(Field, Option<Local>, Type)> {
         self.imp.resolve_record_field(field)
     }
 
@@ -501,14 +501,12 @@ impl<'db> SemanticsImpl<'db> {
     }
 
     fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
-        self.analyze(call.syntax()).resolve_method_call(self.db, call)
+        self.analyze(call.syntax()).resolve_method_call(self.db, call).map(|(id, _)| id)
     }
 
     fn resolve_method_call_as_callable(&self, call: &ast::MethodCallExpr) -> Option<Callable> {
-        // FIXME: this erases Substs, we should instead record the correct
-        // substitution during inference and use that
-        let func = self.resolve_method_call(call)?;
-        let ty = hir_ty::TyBuilder::value_ty(self.db, func.into()).fill_with_unknown().build();
+        let (func, subst) = self.analyze(call.syntax()).resolve_method_call(self.db, call)?;
+        let ty = self.db.value_ty(func.into()).substitute(&Interner, &subst);
         let resolver = self.analyze(call.syntax()).resolver;
         let ty = Type::new_with_resolver(self.db, &resolver, ty)?;
         let mut res = ty.as_callable(self.db)?;
@@ -520,7 +518,10 @@ impl<'db> SemanticsImpl<'db> {
         self.analyze(field.syntax()).resolve_field(self.db, field)
     }
 
-    fn resolve_record_field(&self, field: &ast::RecordExprField) -> Option<(Field, Option<Local>)> {
+    fn resolve_record_field(
+        &self,
+        field: &ast::RecordExprField,
+    ) -> Option<(Field, Option<Local>, Type)> {
         self.analyze(field.syntax()).resolve_record_field(self.db, field)
     }
 
diff --git a/crates/hir/src/source_analyzer.rs b/crates/hir/src/source_analyzer.rs
index 20753314d..3f940124c 100644
--- a/crates/hir/src/source_analyzer.rs
+++ b/crates/hir/src/source_analyzer.rs
@@ -143,7 +143,7 @@ impl SourceAnalyzer {
         &self,
         db: &dyn HirDatabase,
         call: &ast::MethodCallExpr,
-    ) -> Option<FunctionId> {
+    ) -> Option<(FunctionId, Substitution)> {
         let expr_id = self.expr_id(db, &call.clone().into())?;
         self.infer.as_ref()?.method_resolution(expr_id)
     }
@@ -161,7 +161,7 @@ impl SourceAnalyzer {
         &self,
         db: &dyn HirDatabase,
         field: &ast::RecordExprField,
-    ) -> Option<(Field, Option<Local>)> {
+    ) -> Option<(Field, Option<Local>, Type)> {
         let record_expr = ast::RecordExpr::cast(field.syntax().parent().and_then(|p| p.parent())?)?;
         let expr = ast::Expr::from(record_expr);
         let expr_id = self.body_source_map.as_ref()?.node_expr(InFile::new(self.file_id, &expr))?;
@@ -178,10 +178,13 @@ impl SourceAnalyzer {
                 _ => None,
             }
         };
+        let (_, subst) = self.infer.as_ref()?.type_of_expr.get(expr_id)?.as_adt()?;
         let variant = self.infer.as_ref()?.variant_resolution_for_expr(expr_id)?;
         let variant_data = variant.variant_data(db.upcast());
         let field = FieldId { parent: variant, local_id: variant_data.field(&local_name)? };
-        Some((field.into(), local))
+        let field_ty =
+            db.field_types(variant).get(field.local_id)?.clone().substitute(&Interner, subst);
+        Some((field.into(), local, Type::new_with_resolver(db, &self.resolver, field_ty)?))
     }
 
     pub(crate) fn resolve_record_pat_field(
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index 528270d49..4a5f44027 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -1,4 +1,34 @@
 //! A simplified AST that only contains items.
+//!
+//! This is the primary IR used throughout `hir_def`. It is the input to the name resolution
+//! algorithm, as well as to the queries defined in `adt.rs`, `data.rs`, and most things in
+//! `attr.rs`.
+//!
+//! `ItemTree`s are built per `HirFileId`, from the syntax tree of the parsed file. This means that
+//! they are crate-independent: they don't know which `#[cfg]`s are active or which module they
+//! belong to, since those concepts don't exist at this level (a single `ItemTree` might be part of
+//! multiple crates, or might be included into the same crate twice via `#[path]`).
+//!
+//! One important purpose of this layer is to provide an "invalidation barrier" for incremental
+//! computations: when typing inside an item body, the `ItemTree` of the modified file is typically
+//! unaffected, so we don't have to recompute name resolution results or item data (see `data.rs`).
+//!
+//! The `ItemTree` for the currently open file can be displayed by using the VS Code command
+//! "Rust Analyzer: Debug ItemTree".
+//!
+//! Compared to rustc's architecture, `ItemTree` has properties from both rustc's AST and HIR: many
+//! syntax-level Rust features are already desugared to simpler forms in the `ItemTree`, but name
+//! resolution has not yet been performed. `ItemTree`s are per-file, while rustc's AST and HIR are
+//! per-crate, because we are interested in incrementally computing it.
+//!
+//! The representation of items in the `ItemTree` should generally mirror the surface syntax: it is
+//! usually a bad idea to desugar a syntax-level construct to something that is structurally
+//! different here. Name resolution needs to be able to process attributes and expand macros
+//! (including attribute macros), and having a 1-to-1 mapping between syntax and the `ItemTree`
+//! avoids introducing subtle bugs.
+//!
+//! In general, any item in the `ItemTree` stores its `AstId`, which allows mapping it back to its
+//! surface syntax.
 
 mod lower;
 mod pretty;
@@ -500,8 +530,8 @@ pub struct Import {
     pub alias: Option<ImportAlias>,
     pub visibility: RawVisibilityId,
     pub is_glob: bool,
-    /// AST ID of the `use` or `extern crate` item this import was derived from. Note that many
-    /// `Import`s can map to the same `use` item.
+    /// AST ID of the `use` item this import was derived from. Note that many `Import`s can map to
+    /// the same `use` item.
     pub ast_id: FileAstId<ast::Use>,
     /// Index of this `Import` when the containing `Use` is visited via `ModPath::expand_use_item`.
     ///
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index a82ea5957..70001cac8 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -485,6 +485,14 @@ impl VariantId {
             VariantId::UnionId(it) => it.lookup(db).id.file_id(),
         }
     }
+
+    pub fn adt_id(self) -> AdtId {
+        match self {
+            VariantId::EnumVariantId(it) => it.parent.into(),
+            VariantId::StructId(it) => it.into(),
+            VariantId::UnionId(it) => it.into(),
+        }
+    }
 }
 
 trait Intern {
diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 53c4ee9da..d1f113e7f 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -181,7 +181,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         for (id, expr) in body.exprs.iter() {
             if let Expr::MethodCall { receiver, .. } = expr {
                 let function_id = match self.infer.method_resolution(id) {
-                    Some(id) => id,
+                    Some((id, _)) => id,
                     None => continue,
                 };
 
@@ -239,15 +239,11 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                     return;
                 }
 
-                // FIXME: note that we erase information about substs here. This
-                // is not right, but, luckily, doesn't matter as we care only
-                // about the number of params
-                let callee = match self.infer.method_resolution(call_id) {
-                    Some(callee) => callee,
+                let (callee, subst) = match self.infer.method_resolution(call_id) {
+                    Some(it) => it,
                     None => return,
                 };
-                let sig =
-                    db.callable_item_signature(callee.into()).into_value_and_skipped_binders().0;
+                let sig = db.callable_item_signature(callee.into()).substitute(&Interner, &subst);
 
                 (sig, args)
             }
diff --git a/crates/hir_ty/src/diagnostics/unsafe_check.rs b/crates/hir_ty/src/diagnostics/unsafe_check.rs
index ed97dc0e3..5d13bddea 100644
--- a/crates/hir_ty/src/diagnostics/unsafe_check.rs
+++ b/crates/hir_ty/src/diagnostics/unsafe_check.rs
@@ -105,7 +105,7 @@ fn walk_unsafe(
         Expr::MethodCall { .. } => {
             if infer
                 .method_resolution(current)
-                .map(|func| db.function_data(func).is_unsafe())
+                .map(|(func, _)| db.function_data(func).is_unsafe())
                 .unwrap_or(false)
             {
                 unsafe_exprs.push(UnsafeExpr { expr: current, inside_unsafe_block });
diff --git a/crates/hir_ty/src/infer.rs b/crates/hir_ty/src/infer.rs
index f1cebbdb9..db3c937ff 100644
--- a/crates/hir_ty/src/infer.rs
+++ b/crates/hir_ty/src/infer.rs
@@ -37,8 +37,8 @@ use syntax::SmolStr;
 use super::{DomainGoal, InEnvironment, ProjectionTy, TraitEnvironment, TraitRef, Ty};
 use crate::{
     db::HirDatabase, fold_tys, infer::diagnostics::InferenceDiagnostic,
-    lower::ImplTraitLoweringMode, to_assoc_type_id, AliasEq, AliasTy, Goal, Interner, TyBuilder,
-    TyExt, TyKind,
+    lower::ImplTraitLoweringMode, to_assoc_type_id, AliasEq, AliasTy, Goal, Interner, Substitution,
+    TyBuilder, TyExt, TyKind,
 };
 
 // This lint has a false positive here. See the link below for details.
@@ -132,7 +132,7 @@ impl Default for InternedStandardTypes {
 #[derive(Clone, PartialEq, Eq, Debug, Default)]
 pub struct InferenceResult {
     /// For each method call expr, records the function it resolves to.
-    method_resolutions: FxHashMap<ExprId, FunctionId>,
+    method_resolutions: FxHashMap<ExprId, (FunctionId, Substitution)>,
     /// For each field access expr, records the field it resolves to.
     field_resolutions: FxHashMap<ExprId, FieldId>,
     /// For each struct literal or pattern, records the variant it resolves to.
@@ -152,8 +152,8 @@ pub struct InferenceResult {
 }
 
 impl InferenceResult {
-    pub fn method_resolution(&self, expr: ExprId) -> Option<FunctionId> {
-        self.method_resolutions.get(&expr).copied()
+    pub fn method_resolution(&self, expr: ExprId) -> Option<(FunctionId, Substitution)> {
+        self.method_resolutions.get(&expr).cloned()
     }
     pub fn field_resolution(&self, expr: ExprId) -> Option<FieldId> {
         self.field_resolutions.get(&expr).copied()
@@ -284,14 +284,17 @@ impl<'a> InferenceContext<'a> {
         self.table.propagate_diverging_flag();
         let mut result = std::mem::take(&mut self.result);
         for ty in result.type_of_expr.values_mut() {
-            *ty = self.table.resolve_ty_completely(ty.clone());
+            *ty = self.table.resolve_completely(ty.clone());
         }
         for ty in result.type_of_pat.values_mut() {
-            *ty = self.table.resolve_ty_completely(ty.clone());
+            *ty = self.table.resolve_completely(ty.clone());
         }
         for mismatch in result.type_mismatches.values_mut() {
-            mismatch.expected = self.table.resolve_ty_completely(mismatch.expected.clone());
-            mismatch.actual = self.table.resolve_ty_completely(mismatch.actual.clone());
+            mismatch.expected = self.table.resolve_completely(mismatch.expected.clone());
+            mismatch.actual = self.table.resolve_completely(mismatch.actual.clone());
+        }
+        for (_, subst) in result.method_resolutions.values_mut() {
+            *subst = self.table.resolve_completely(subst.clone());
         }
         result
     }
@@ -300,8 +303,8 @@ impl<'a> InferenceContext<'a> {
         self.result.type_of_expr.insert(expr, ty);
     }
 
-    fn write_method_resolution(&mut self, expr: ExprId, func: FunctionId) {
-        self.result.method_resolutions.insert(expr, func);
+    fn write_method_resolution(&mut self, expr: ExprId, func: FunctionId, subst: Substitution) {
+        self.result.method_resolutions.insert(expr, (func, subst));
     }
 
     fn write_field_resolution(&mut self, expr: ExprId, field: FieldId) {
diff --git a/crates/hir_ty/src/infer/expr.rs b/crates/hir_ty/src/infer/expr.rs
index 08c05c67c..eab8fac91 100644
--- a/crates/hir_ty/src/infer/expr.rs
+++ b/crates/hir_ty/src/infer/expr.rs
@@ -891,17 +891,21 @@ impl<'a> InferenceContext<'a> {
                 method_name,
             )
         });
-        let (derefed_receiver_ty, method_ty, def_generics) = match resolved {
+        let (derefed_receiver_ty, method_ty, substs) = match resolved {
             Some((ty, func)) => {
                 let ty = canonicalized_receiver.decanonicalize_ty(ty);
-                self.write_method_resolution(tgt_expr, func);
-                (ty, self.db.value_ty(func.into()), Some(generics(self.db.upcast(), func.into())))
+                let generics = generics(self.db.upcast(), func.into());
+                let substs = self.substs_for_method_call(generics, generic_args, &ty);
+                self.write_method_resolution(tgt_expr, func, substs.clone());
+                (ty, self.db.value_ty(func.into()), substs)
             }
-            None => (receiver_ty, Binders::empty(&Interner, self.err_ty()), None),
+            None => (
+                receiver_ty,
+                Binders::empty(&Interner, self.err_ty()),
+                Substitution::empty(&Interner),
+            ),
         };
-        let substs = self.substs_for_method_call(def_generics, generic_args, &derefed_receiver_ty);
         let method_ty = method_ty.substitute(&Interner, &substs);
-        let method_ty = self.insert_type_vars(method_ty);
         self.register_obligations_for_call(&method_ty);
         let (expected_receiver_ty, param_tys, ret_ty) = match method_ty.callable_sig(self.db) {
             Some(sig) => {
@@ -950,23 +954,21 @@ impl<'a> InferenceContext<'a> {
 
     fn substs_for_method_call(
         &mut self,
-        def_generics: Option<Generics>,
+        def_generics: Generics,
         generic_args: Option<&GenericArgs>,
         receiver_ty: &Ty,
     ) -> Substitution {
         let (parent_params, self_params, type_params, impl_trait_params) =
-            def_generics.as_ref().map_or((0, 0, 0, 0), |g| g.provenance_split());
+            def_generics.provenance_split();
         assert_eq!(self_params, 0); // method shouldn't have another Self param
         let total_len = parent_params + type_params + impl_trait_params;
         let mut substs = Vec::with_capacity(total_len);
         // Parent arguments are unknown, except for the receiver type
-        if let Some(parent_generics) = def_generics.as_ref().map(|p| p.iter_parent()) {
-            for (_id, param) in parent_generics {
-                if param.provenance == hir_def::generics::TypeParamProvenance::TraitSelf {
-                    substs.push(receiver_ty.clone());
-                } else {
-                    substs.push(self.err_ty());
-                }
+        for (_id, param) in def_generics.iter_parent() {
+            if param.provenance == hir_def::generics::TypeParamProvenance::TraitSelf {
+                substs.push(receiver_ty.clone());
+            } else {
+                substs.push(self.table.new_type_var());
             }
         }
         // handle provided type arguments
@@ -989,7 +991,7 @@ impl<'a> InferenceContext<'a> {
         };
         let supplied_params = substs.len();
         for _ in supplied_params..total_len {
-            substs.push(self.err_ty());
+            substs.push(self.table.new_type_var());
         }
         assert_eq!(substs.len(), total_len);
         Substitution::from_iter(&Interner, substs)
diff --git a/crates/hir_ty/src/infer/unify.rs b/crates/hir_ty/src/infer/unify.rs
index f8233cac3..ea5684229 100644
--- a/crates/hir_ty/src/infer/unify.rs
+++ b/crates/hir_ty/src/infer/unify.rs
@@ -295,8 +295,11 @@ impl<'a> InferenceTable<'a> {
         .expect("fold failed unexpectedly")
     }
 
-    pub(crate) fn resolve_ty_completely(&mut self, ty: Ty) -> Ty {
-        self.resolve_with_fallback(ty, |_, _, d, _| d)
+    pub(crate) fn resolve_completely<T>(&mut self, t: T) -> T::Result
+    where
+        T: HasInterner<Interner = Interner> + Fold<Interner>,
+    {
+        self.resolve_with_fallback(t, |_, _, d, _| d)
     }
 
     /// Unify two types and register new trait goals that arise from that.
diff --git a/crates/ide_assists/src/handlers/fix_visibility.rs b/crates/ide_assists/src/handlers/fix_visibility.rs
index 6c7824e55..89f7b2c2c 100644
--- a/crates/ide_assists/src/handlers/fix_visibility.rs
+++ b/crates/ide_assists/src/handlers/fix_visibility.rs
@@ -85,7 +85,7 @@ fn add_vis_to_referenced_module_def(acc: &mut Assists, ctx: &AssistContext) -> O
 
 fn add_vis_to_referenced_record_field(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
     let record_field: ast::RecordExprField = ctx.find_node_at_offset()?;
-    let (record_field_def, _) = ctx.sema.resolve_record_field(&record_field)?;
+    let (record_field_def, _, _) = ctx.sema.resolve_record_field(&record_field)?;
 
     let current_module = ctx.sema.scope(record_field.syntax()).module()?;
     let visibility = record_field_def.visibility(ctx.db());
diff --git a/crates/ide_assists/src/handlers/generate_getter.rs b/crates/ide_assists/src/handlers/generate_getter.rs
index df7d1bb95..09971226e 100644
--- a/crates/ide_assists/src/handlers/generate_getter.rs
+++ b/crates/ide_assists/src/handlers/generate_getter.rs
@@ -23,12 +23,46 @@ use crate::{
 //
 // impl Person {
 //     /// Get a reference to the person's name.
-//     fn name(&self) -> &String {
-//         &self.name
+//     fn $0name(&self) -> &str {
+//         self.name.as_str()
 //     }
 // }
 // ```
 pub(crate) fn generate_getter(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_getter_impl(acc, ctx, false)
+}
+
+// Assist: generate_getter_mut
+//
+// Generate a mut getter method.
+//
+// ```
+// struct Person {
+//     nam$0e: String,
+// }
+// ```
+// ->
+// ```
+// struct Person {
+//     name: String,
+// }
+//
+// impl Person {
+//     /// Get a mutable reference to the person's name.
+//     fn $0name_mut(&mut self) -> &mut String {
+//         &mut self.name
+//     }
+// }
+// ```
+pub(crate) fn generate_getter_mut(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    generate_getter_impl(acc, ctx, true)
+}
+
+pub(crate) fn generate_getter_impl(
+    acc: &mut Assists,
+    ctx: &AssistContext,
+    mutable: bool,
+) -> Option<()> {
     let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
     let field = ctx.find_node_at_offset::<ast::RecordField>()?;
 
@@ -37,39 +71,52 @@ pub(crate) fn generate_getter(acc: &mut Assists, ctx: &AssistContext) -> Option<
     let field_ty = field.ty()?;
 
     // Return early if we've found an existing fn
-    let fn_name = to_lower_snake_case(&field_name.to_string());
+    let mut fn_name = to_lower_snake_case(&field_name.to_string());
+    if mutable {
+        format_to!(fn_name, "_mut");
+    }
     let impl_def = find_struct_impl(&ctx, &ast::Adt::Struct(strukt.clone()), fn_name.as_str())?;
 
+    let (id, label) = if mutable {
+        ("generate_getter_mut", "Generate a mut getter method")
+    } else {
+        ("generate_getter", "Generate a getter method")
+    };
     let target = field.syntax().text_range();
     acc.add_group(
         &GroupLabel("Generate getter/setter".to_owned()),
-        AssistId("generate_getter", AssistKind::Generate),
-        "Generate a getter method",
+        AssistId(id, AssistKind::Generate),
+        label,
         target,
         |builder| {
             let mut buf = String::with_capacity(512);
 
-            let fn_name_spaced = fn_name.replace('_', " ");
-            let strukt_name_spaced =
-                to_lower_snake_case(&strukt_name.to_string()).replace('_', " ");
-
             if impl_def.is_some() {
                 buf.push('\n');
             }
 
             let vis = strukt.visibility().map_or(String::new(), |v| format!("{} ", v));
+            let (ty, body) = if mutable {
+                (format!("&mut {}", field_ty), format!("&mut self.{}", field_name))
+            } else {
+                useless_type_special_case(&field_name.to_string(), &field_ty)
+                    .unwrap_or_else(|| (format!("&{}", field_ty), format!("&self.{}", field_name)))
+            };
+
             format_to!(
                 buf,
-                "    /// Get a reference to the {}'s {}.
-    {}fn {}(&self) -> &{} {{
-        &self.{}
+                "    /// Get a {}reference to the {}'s {}.
+    {}fn {}(&{}self) -> {} {{
+        {}
     }}",
-                strukt_name_spaced,
-                fn_name_spaced,
+                mutable.then(|| "mutable ").unwrap_or_default(),
+                to_lower_snake_case(&strukt_name.to_string()).replace('_', " "),
+                fn_name.trim_end_matches("_mut").replace('_', " "),
                 vis,
                 fn_name,
-                field_ty,
-                fn_name,
+                mutable.then(|| "mut ").unwrap_or_default(),
+                ty,
+                body,
             );
 
             let start_offset = impl_def
@@ -79,56 +126,120 @@ pub(crate) fn generate_getter(acc: &mut Assists, ctx: &AssistContext) -> Option<
                     strukt.syntax().text_range().end()
                 });
 
-            builder.insert(start_offset, buf);
+            match ctx.config.snippet_cap {
+                Some(cap) => {
+                    builder.insert_snippet(cap, start_offset, buf.replacen("fn ", "fn $0", 1))
+                }
+                None => builder.insert(start_offset, buf),
+            }
         },
     )
 }
 
+fn useless_type_special_case(field_name: &str, field_ty: &ast::Type) -> Option<(String, String)> {
+    if field_ty.to_string() == "String" {
+        cov_mark::hit!(useless_type_special_case);
+        return Some(("&str".to_string(), format!("self.{}.as_str()", field_name)));
+    }
+    if let Some(arg) = ty_ctor(field_ty, "Vec") {
+        return Some((format!("&[{}]", arg), format!("self.{}.as_slice()", field_name)));
+    }
+    if let Some(arg) = ty_ctor(field_ty, "Box") {
+        return Some((format!("&{}", arg), format!("self.{}.as_ref()", field_name)));
+    }
+    if let Some(arg) = ty_ctor(field_ty, "Option") {
+        return Some((format!("Option<&{}>", arg), format!("self.{}.as_ref()", field_name)));
+    }
+    None
+}
+
+// FIXME: This should rely on semantic info.
+fn ty_ctor(ty: &ast::Type, ctor: &str) -> Option<String> {
+    let res = ty.to_string().strip_prefix(ctor)?.strip_prefix('<')?.strip_suffix('>')?.to_string();
+    Some(res)
+}
+
 #[cfg(test)]
 mod tests {
     use crate::tests::{check_assist, check_assist_not_applicable};
 
     use super::*;
 
-    fn check_not_applicable(ra_fixture: &str) {
-        check_assist_not_applicable(generate_getter, ra_fixture)
-    }
-
     #[test]
     fn test_generate_getter_from_field() {
         check_assist(
             generate_getter,
             r#"
-struct Context<T: Clone> {
-    dat$0a: T,
-}"#,
+struct Context {
+    dat$0a: Data,
+}
+"#,
             r#"
-struct Context<T: Clone> {
-    data: T,
+struct Context {
+    data: Data,
 }
 
-impl<T: Clone> Context<T> {
+impl Context {
     /// Get a reference to the context's data.
-    fn data(&self) -> &T {
+    fn $0data(&self) -> &Data {
         &self.data
     }
-}"#,
+}
+"#,
+        );
+
+        check_assist(
+            generate_getter_mut,
+            r#"
+struct Context {
+    dat$0a: Data,
+}
+"#,
+            r#"
+struct Context {
+    data: Data,
+}
+
+impl Context {
+    /// Get a mutable reference to the context's data.
+    fn $0data_mut(&mut self) -> &mut Data {
+        &mut self.data
+    }
+}
+"#,
         );
     }
 
     #[test]
     fn test_generate_getter_already_implemented() {
-        check_not_applicable(
+        check_assist_not_applicable(
+            generate_getter,
             r#"
-struct Context<T: Clone> {
-    dat$0a: T,
+struct Context {
+    dat$0a: Data,
 }
 
-impl<T: Clone> Context<T> {
-    fn data(&self) -> &T {
+impl Context {
+    fn data(&self) -> &Data {
         &self.data
     }
-}"#,
+}
+"#,
+        );
+
+        check_assist_not_applicable(
+            generate_getter_mut,
+            r#"
+struct Context {
+    dat$0a: Data,
+}
+
+impl Context {
+    fn data_mut(&mut self) -> &mut Data {
+        &mut self.data
+    }
+}
+"#,
         );
     }
 
@@ -137,20 +248,22 @@ impl<T: Clone> Context<T> {
         check_assist(
             generate_getter,
             r#"
-pub(crate) struct Context<T: Clone> {
-    dat$0a: T,
-}"#,
+pub(crate) struct Context {
+    dat$0a: Data,
+}
+"#,
             r#"
-pub(crate) struct Context<T: Clone> {
-    data: T,
+pub(crate) struct Context {
+    data: Data,
 }
 
-impl<T: Clone> Context<T> {
+impl Context {
     /// Get a reference to the context's data.
-    pub(crate) fn data(&self) -> &T {
+    pub(crate) fn $0data(&self) -> &Data {
         &self.data
     }
-}"#,
+}
+"#,
         );
     }
 
@@ -159,34 +272,105 @@ impl<T: Clone> Context<T> {
         check_assist(
             generate_getter,
             r#"
-struct Context<T: Clone> {
-    data: T,
+struct Context {
+    data: Data,
     cou$0nt: usize,
 }
 
-impl<T: Clone> Context<T> {
+impl Context {
     /// Get a reference to the context's data.
-    fn data(&self) -> &T {
+    fn data(&self) -> &Data {
         &self.data
     }
-}"#,
+}
+"#,
             r#"
-struct Context<T: Clone> {
-    data: T,
+struct Context {
+    data: Data,
     count: usize,
 }
 
-impl<T: Clone> Context<T> {
+impl Context {
     /// Get a reference to the context's data.
-    fn data(&self) -> &T {
+    fn data(&self) -> &Data {
         &self.data
     }
 
     /// Get a reference to the context's count.
-    fn count(&self) -> &usize {
+    fn $0count(&self) -> &usize {
         &self.count
     }
-}"#,
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_special_cases() {
+        cov_mark::check!(useless_type_special_case);
+        check_assist(
+            generate_getter,
+            r#"
+struct S { foo: $0String }
+"#,
+            r#"
+struct S { foo: String }
+
+impl S {
+    /// Get a reference to the s's foo.
+    fn $0foo(&self) -> &str {
+        self.foo.as_str()
+    }
+}
+"#,
+        );
+        check_assist(
+            generate_getter,
+            r#"
+struct S { foo: $0Box<Sweets> }
+"#,
+            r#"
+struct S { foo: Box<Sweets> }
+
+impl S {
+    /// Get a reference to the s's foo.
+    fn $0foo(&self) -> &Sweets {
+        self.foo.as_ref()
+    }
+}
+"#,
+        );
+        check_assist(
+            generate_getter,
+            r#"
+struct S { foo: $0Vec<()> }
+"#,
+            r#"
+struct S { foo: Vec<()> }
+
+impl S {
+    /// Get a reference to the s's foo.
+    fn $0foo(&self) -> &[()] {
+        self.foo.as_slice()
+    }
+}
+"#,
+        );
+        check_assist(
+            generate_getter,
+            r#"
+struct S { foo: $0Option<Failure> }
+"#,
+            r#"
+struct S { foo: Option<Failure> }
+
+impl S {
+    /// Get a reference to the s's foo.
+    fn $0foo(&self) -> Option<&Failure> {
+        self.foo.as_ref()
+    }
+}
+"#,
         );
     }
 }
diff --git a/crates/ide_assists/src/handlers/generate_getter_mut.rs b/crates/ide_assists/src/handlers/generate_getter_mut.rs
deleted file mode 100644
index 821c2eed5..000000000
--- a/crates/ide_assists/src/handlers/generate_getter_mut.rs
+++ /dev/null
@@ -1,195 +0,0 @@
-use stdx::{format_to, to_lower_snake_case};
-use syntax::ast::{self, AstNode, NameOwner, VisibilityOwner};
-
-use crate::{
-    utils::{find_impl_block_end, find_struct_impl, generate_impl_text},
-    AssistContext, AssistId, AssistKind, Assists, GroupLabel,
-};
-
-// Assist: generate_getter_mut
-//
-// Generate a mut getter method.
-//
-// ```
-// struct Person {
-//     nam$0e: String,
-// }
-// ```
-// ->
-// ```
-// struct Person {
-//     name: String,
-// }
-//
-// impl Person {
-//     /// Get a mutable reference to the person's name.
-//     fn name_mut(&mut self) -> &mut String {
-//         &mut self.name
-//     }
-// }
-// ```
-pub(crate) fn generate_getter_mut(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
-    let strukt = ctx.find_node_at_offset::<ast::Struct>()?;
-    let field = ctx.find_node_at_offset::<ast::RecordField>()?;
-
-    let strukt_name = strukt.name()?;
-    let field_name = field.name()?;
-    let field_ty = field.ty()?;
-
-    // Return early if we've found an existing fn
-    let fn_name = to_lower_snake_case(&field_name.to_string());
-    let impl_def = find_struct_impl(
-        &ctx,
-        &ast::Adt::Struct(strukt.clone()),
-        format!("{}_mut", fn_name).as_str(),
-    )?;
-
-    let target = field.syntax().text_range();
-    acc.add_group(
-        &GroupLabel("Generate getter/setter".to_owned()),
-        AssistId("generate_getter_mut", AssistKind::Generate),
-        "Generate a mut getter method",
-        target,
-        |builder| {
-            let mut buf = String::with_capacity(512);
-            let fn_name_spaced = fn_name.replace('_', " ");
-            let strukt_name_spaced =
-                to_lower_snake_case(&strukt_name.to_string()).replace('_', " ");
-
-            if impl_def.is_some() {
-                buf.push('\n');
-            }
-
-            let vis = strukt.visibility().map_or(String::new(), |v| format!("{} ", v));
-            format_to!(
-                buf,
-                "    /// Get a mutable reference to the {}'s {}.
-    {}fn {}_mut(&mut self) -> &mut {} {{
-        &mut self.{}
-    }}",
-                strukt_name_spaced,
-                fn_name_spaced,
-                vis,
-                fn_name,
-                field_ty,
-                fn_name,
-            );
-
-            let start_offset = impl_def
-                .and_then(|impl_def| find_impl_block_end(impl_def, &mut buf))
-                .unwrap_or_else(|| {
-                    buf = generate_impl_text(&ast::Adt::Struct(strukt.clone()), &buf);
-                    strukt.syntax().text_range().end()
-                });
-
-            builder.insert(start_offset, buf);
-        },
-    )
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::tests::{check_assist, check_assist_not_applicable};
-
-    use super::*;
-
-    fn check_not_applicable(ra_fixture: &str) {
-        check_assist_not_applicable(generate_getter_mut, ra_fixture)
-    }
-
-    #[test]
-    fn test_generate_getter_mut_from_field() {
-        check_assist(
-            generate_getter_mut,
-            r#"
-struct Context<T: Clone> {
-    dat$0a: T,
-}"#,
-            r#"
-struct Context<T: Clone> {
-    data: T,
-}
-
-impl<T: Clone> Context<T> {
-    /// Get a mutable reference to the context's data.
-    fn data_mut(&mut self) -> &mut T {
-        &mut self.data
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn test_generate_getter_mut_already_implemented() {
-        check_not_applicable(
-            r#"
-struct Context<T: Clone> {
-    dat$0a: T,
-}
-
-impl<T: Clone> Context<T> {
-    fn data_mut(&mut self) -> &mut T {
-        &mut self.data
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn test_generate_getter_mut_from_field_with_visibility_marker() {
-        check_assist(
-            generate_getter_mut,
-            r#"
-pub(crate) struct Context<T: Clone> {
-    dat$0a: T,
-}"#,
-            r#"
-pub(crate) struct Context<T: Clone> {
-    data: T,
-}
-
-impl<T: Clone> Context<T> {
-    /// Get a mutable reference to the context's data.
-    pub(crate) fn data_mut(&mut self) -> &mut T {
-        &mut self.data
-    }
-}"#,
-        );
-    }
-
-    #[test]
-    fn test_multiple_generate_getter_mut() {
-        check_assist(
-            generate_getter_mut,
-            r#"
-struct Context<T: Clone> {
-    data: T,
-    cou$0nt: usize,
-}
-
-impl<T: Clone> Context<T> {
-    /// Get a mutable reference to the context's data.
-    fn data_mut(&mut self) -> &mut T {
-        &mut self.data
-    }
-}"#,
-            r#"
-struct Context<T: Clone> {
-    data: T,
-    count: usize,
-}
-
-impl<T: Clone> Context<T> {
-    /// Get a mutable reference to the context's data.
-    fn data_mut(&mut self) -> &mut T {
-        &mut self.data
-    }
-
-    /// Get a mutable reference to the context's count.
-    fn count_mut(&mut self) -> &mut usize {
-        &mut self.count
-    }
-}"#,
-        );
-    }
-}
diff --git a/crates/ide_assists/src/lib.rs b/crates/ide_assists/src/lib.rs
index 4cd82f8c1..16af72927 100644
--- a/crates/ide_assists/src/lib.rs
+++ b/crates/ide_assists/src/lib.rs
@@ -206,7 +206,6 @@ mod handlers {
     mod generate_enum_projection_method;
     mod generate_from_impl_for_enum;
     mod generate_function;
-    mod generate_getter_mut;
     mod generate_getter;
     mod generate_impl;
     mod generate_new;
@@ -276,8 +275,8 @@ mod handlers {
             generate_enum_projection_method::generate_enum_try_into_method,
             generate_from_impl_for_enum::generate_from_impl_for_enum,
             generate_function::generate_function,
-            generate_getter_mut::generate_getter_mut,
             generate_getter::generate_getter,
+            generate_getter::generate_getter_mut,
             generate_impl::generate_impl,
             generate_new::generate_new,
             generate_setter::generate_setter,
diff --git a/crates/ide_assists/src/tests.rs b/crates/ide_assists/src/tests.rs
index 6a9231e07..2b7c2d581 100644
--- a/crates/ide_assists/src/tests.rs
+++ b/crates/ide_assists/src/tests.rs
@@ -215,8 +215,8 @@ fn assist_order_field_struct() {
 
     assert_eq!(assists.next().expect("expected assist").label, "Change visibility to pub(crate)");
     assert_eq!(assists.next().expect("expected assist").label, "Generate `Deref` impl using `bar`");
-    assert_eq!(assists.next().expect("expected assist").label, "Generate a mut getter method");
     assert_eq!(assists.next().expect("expected assist").label, "Generate a getter method");
+    assert_eq!(assists.next().expect("expected assist").label, "Generate a mut getter method");
     assert_eq!(assists.next().expect("expected assist").label, "Generate a setter method");
     assert_eq!(assists.next().expect("expected assist").label, "Add `#[derive]`");
 }
diff --git a/crates/ide_assists/src/tests/generated.rs b/crates/ide_assists/src/tests/generated.rs
index 4406406a2..8a9b0777c 100644
--- a/crates/ide_assists/src/tests/generated.rs
+++ b/crates/ide_assists/src/tests/generated.rs
@@ -786,8 +786,8 @@ struct Person {
 
 impl Person {
     /// Get a reference to the person's name.
-    fn name(&self) -> &String {
-        &self.name
+    fn $0name(&self) -> &str {
+        self.name.as_str()
     }
 }
 "#####,
@@ -810,7 +810,7 @@ struct Person {
 
 impl Person {
     /// Get a mutable reference to the person's name.
-    fn name_mut(&mut self) -> &mut String {
+    fn $0name_mut(&mut self) -> &mut String {
         &mut self.name
     }
 }
diff --git a/crates/ide_completion/src/context.rs b/crates/ide_completion/src/context.rs
index 787eb2fd3..1ec59ff80 100644
--- a/crates/ide_completion/src/context.rs
+++ b/crates/ide_completion/src/context.rs
@@ -337,25 +337,24 @@ impl<'a> CompletionContext<'a> {
                     },
                     ast::RecordExprFieldList(_it) => {
                         cov_mark::hit!(expected_type_struct_field_without_leading_char);
-                        self.token.prev_sibling_or_token()
-                            .and_then(|se| se.into_node())
-                            .and_then(|node| ast::RecordExprField::cast(node))
-                            .and_then(|rf| self.sema.resolve_record_field(&rf).zip(Some(rf)))
-                            .map(|(f, rf)|(
-                                Some(f.0.ty(self.db)),
-                                rf.field_name().map(NameOrNameRef::NameRef),
+                        // wouldn't try {} be nice...
+                        (|| {
+                            let expr_field = self.token.prev_sibling_or_token()?
+                                      .into_node()
+                                      .and_then(|node| ast::RecordExprField::cast(node))?;
+                            let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
+                            Some((
+                                Some(ty),
+                                expr_field.field_name().map(NameOrNameRef::NameRef),
                             ))
-                            .unwrap_or((None, None))
+                        })().unwrap_or((None, None))
                     },
                     ast::RecordExprField(it) => {
                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
-                        self.sema
-                            .resolve_record_field(&it)
-                            .map(|f|(
-                                Some(f.0.ty(self.db)),
-                                it.field_name().map(NameOrNameRef::NameRef),
-                            ))
-                            .unwrap_or((None, None))
+                        (
+                            it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)),
+                            it.field_name().map(NameOrNameRef::NameRef),
+                        )
                     },
                     ast::MatchExpr(it) => {
                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
@@ -382,6 +381,12 @@ impl<'a> CompletionContext<'a> {
                         let def = self.sema.to_def(&it);
                         (def.map(|def| def.ret_type(self.db)), None)
                     },
+                    ast::ClosureExpr(it) => {
+                        let ty = self.sema.type_of_expr(&it.into());
+                        ty.and_then(|ty| ty.as_callable(self.db))
+                            .map(|c| (Some(c.return_type()), None))
+                            .unwrap_or((None, None))
+                    },
                     ast::Stmt(_it) => (None, None),
                     _ => {
                         match node.parent() {
@@ -785,6 +790,19 @@ fn foo() {
     }
 
     #[test]
+    fn expected_type_generic_struct_field() {
+        check_expected_type_and_name(
+            r#"
+struct Foo<T> { a: T }
+fn foo() -> Foo<u32> {
+    Foo { a: $0 }
+}
+"#,
+            expect![[r#"ty: u32, name: a"#]],
+        )
+    }
+
+    #[test]
     fn expected_type_struct_field_with_leading_char() {
         cov_mark::check!(expected_type_struct_field_with_leading_char);
         check_expected_type_and_name(
@@ -895,4 +913,52 @@ fn foo() -> u32 {
             expect![[r#"ty: u32, name: ?"#]],
         )
     }
+
+    #[test]
+    fn expected_type_closure_param_return() {
+        // FIXME: make this work with `|| $0`
+        check_expected_type_and_name(
+            r#"
+fn foo() {
+    bar(|| a$0);
+}
+
+fn bar(f: impl FnOnce() -> u32) {}
+#[lang = "fn_once"]
+trait FnOnce { type Output; }
+"#,
+            expect![[r#"ty: u32, name: ?"#]],
+        );
+    }
+
+    #[test]
+    fn expected_type_generic_function() {
+        check_expected_type_and_name(
+            r#"
+fn foo() {
+    bar::<u32>($0);
+}
+
+fn bar<T>(t: T) {}
+"#,
+            expect![[r#"ty: u32, name: t"#]],
+        );
+    }
+
+    #[test]
+    fn expected_type_generic_method() {
+        check_expected_type_and_name(
+            r#"
+fn foo() {
+    S(1u32).bar($0);
+}
+
+struct S<T>(T);
+impl<T> S<T> {
+    fn bar(self, t: T) {}
+}
+"#,
+            expect![[r#"ty: u32, name: t"#]],
+        );
+    }
 }
diff --git a/crates/ide_completion/src/render.rs b/crates/ide_completion/src/render.rs
index 6b04ee164..d7f96b864 100644
--- a/crates/ide_completion/src/render.rs
+++ b/crates/ide_completion/src/render.rs
@@ -667,6 +667,13 @@ fn foo() { A { the$0 } }
                         ),
                         detail: "u32",
                         deprecated: true,
+                        relevance: CompletionRelevance {
+                            exact_name_match: false,
+                            type_match: Some(
+                                CouldUnify,
+                            ),
+                            is_local: false,
+                        },
                     },
                 ]
             "#]],
diff --git a/crates/ide_db/src/call_info/tests.rs b/crates/ide_db/src/call_info/tests.rs
index be1cc12de..1aeda08e5 100644
--- a/crates/ide_db/src/call_info/tests.rs
+++ b/crates/ide_db/src/call_info/tests.rs
@@ -189,6 +189,24 @@ fn main() { S.foo($0); }
 }
 
 #[test]
+fn test_fn_signature_for_generic_method() {
+    check(
+        r#"
+struct S<T>(T);
+impl<T> S<T> {
+    fn foo(&self, x: T) {}
+}
+
+fn main() { S(1u32).foo($0); }
+"#,
+        expect![[r#"
+                fn foo(&self, x: u32)
+                (<x: u32>)
+            "#]],
+    );
+}
+
+#[test]
 fn test_fn_signature_for_method_with_arg_as_assoc_fn() {
     check(
         r#"
diff --git a/crates/ide_db/src/defs.rs b/crates/ide_db/src/defs.rs
index de0dc2a40..1dcccbb8b 100644
--- a/crates/ide_db/src/defs.rs
+++ b/crates/ide_db/src/defs.rs
@@ -311,7 +311,7 @@ impl NameRefClass {
         }
 
         if let Some(record_field) = ast::RecordExprField::for_field_name(name_ref) {
-            if let Some((field, local)) = sema.resolve_record_field(&record_field) {
+            if let Some((field, local, _)) = sema.resolve_record_field(&record_field) {
                 let field = Definition::Field(field);
                 let res = match local {
                     None => NameRefClass::Definition(field),
diff --git a/crates/ide_db/src/ty_filter.rs b/crates/ide_db/src/ty_filter.rs
index 00678bf3e..766d8c628 100644
--- a/crates/ide_db/src/ty_filter.rs
+++ b/crates/ide_db/src/ty_filter.rs
@@ -4,7 +4,7 @@
 
 use std::iter;
 
-use hir::{Adt, Semantics, Type};
+use hir::Semantics;
 use syntax::ast::{self, make};
 
 use crate::RootDatabase;
@@ -20,9 +20,9 @@ impl TryEnum {
     const ALL: [TryEnum; 2] = [TryEnum::Option, TryEnum::Result];
 
     /// Returns `Some(..)` if the provided type is an enum that implements `std::ops::Try`.
-    pub fn from_ty(sema: &Semantics<RootDatabase>, ty: &Type) -> Option<TryEnum> {
+    pub fn from_ty(sema: &Semantics<RootDatabase>, ty: &hir::Type) -> Option<TryEnum> {
         let enum_ = match ty.as_adt() {
-            Some(Adt::Enum(it)) => it,
+            Some(hir::Adt::Enum(it)) => it,
             _ => return None,
         };
         TryEnum::ALL.iter().find_map(|&var| {
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index fbb7a556a..d3d6e631a 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -34,7 +34,7 @@ export class Config {
     readonly globalStoragePath: string;
 
     constructor(ctx: vscode.ExtensionContext) {
-        this.globalStoragePath = ctx.globalStorageUri.path;
+        this.globalStoragePath = ctx.globalStorageUri.fsPath;
         vscode.workspace.onDidChangeConfiguration(this.onDidChangeConfiguration, this, ctx.subscriptions);
         this.refreshLogging();
     }
diff --git a/editors/code/src/snippets.ts b/editors/code/src/snippets.ts
index 9561aa345..58f7aa128 100644
--- a/editors/code/src/snippets.ts
+++ b/editors/code/src/snippets.ts
@@ -56,6 +56,9 @@ export async function applySnippetTextEdits(editor: vscode.TextEditor, edits: vs
         }
     });
     if (selections.length > 0) editor.selections = selections;
+    if (selections.length === 1) {
+        editor.revealRange(selections[0], vscode.TextEditorRevealType.InCenterIfOutsideViewport);
+    }
 }
 
 function parseSnippet(snip: string): [string, [number, number]] | undefined {
diff --git a/xtask/src/dist.rs b/xtask/src/dist.rs
index 270719de7..7ac9ae5b8 100644
--- a/xtask/src/dist.rs
+++ b/xtask/src/dist.rs
@@ -66,12 +66,8 @@ fn dist_client(version: &str, release_tag: &str) -> Result<()> {
 
 fn dist_server(release_channel: &str) -> Result<()> {
     let _e = pushenv("RUST_ANALYZER_CHANNEL", release_channel);
-    let _e = pushenv("CARGO_PROFILE_RELEASE_LTO", "true");
-
-    // We want do enable debug symbols, but this causes our windows CI to fail:
-    // https://github.com/rust-lang/rust/issues/85598
-    //
-    // let _e = pushenv("CARGO_PROFILE_RELEASE_DEBUG", "1");
+    let _e = pushenv("CARGO_PROFILE_RELEASE_LTO", "thin");
+    let _e = pushenv("CARGO_PROFILE_RELEASE_DEBUG", "1");
 
     let target = get_target();
     if target.contains("-linux-gnu") || target.contains("-linux-musl") {