16 files changed, 342 insertions, 111 deletions

diff --git a/crates/assists/src/handlers/fill_match_arms.rs b/crates/assists/src/handlers/fill_match_arms.rs
index da47187e4..7663d211d 100644
--- a/crates/assists/src/handlers/fill_match_arms.rs
+++ b/crates/assists/src/handlers/fill_match_arms.rs
@@ -8,7 +8,7 @@ use syntax::ast::{self, make, AstNode, MatchArm, NameOwner, Pat};
 use test_utils::mark;
 
 use crate::{
-    utils::{render_snippet, Cursor},
+    utils::{does_pat_match_variant, render_snippet, Cursor},
     AssistContext, AssistId, AssistKind, Assists,
 };
 
@@ -147,25 +147,6 @@ fn is_variant_missing(existing_arms: &mut Vec<MatchArm>, var: &Pat) -> bool {
     })
 }
 
-fn does_pat_match_variant(pat: &Pat, var: &Pat) -> bool {
-    let first_node_text = |pat: &Pat| pat.syntax().first_child().map(|node| node.text());
-
-    let pat_head = match pat {
-        Pat::IdentPat(bind_pat) => {
-            if let Some(p) = bind_pat.pat() {
-                first_node_text(&p)
-            } else {
-                return false;
-            }
-        }
-        pat => first_node_text(pat),
-    };
-
-    let var_head = first_node_text(var);
-
-    pat_head == var_head
-}
-
 fn resolve_enum_def(sema: &Semantics<RootDatabase>, expr: &ast::Expr) -> Option<hir::Enum> {
     sema.type_of_expr(&expr)?.autoderef(sema.db).find_map(|ty| match ty.as_adt() {
         Some(Adt::Enum(e)) => Some(e),
diff --git a/crates/assists/src/handlers/replace_if_let_with_match.rs b/crates/assists/src/handlers/replace_if_let_with_match.rs
index aee3397ab..aee880625 100644
--- a/crates/assists/src/handlers/replace_if_let_with_match.rs
+++ b/crates/assists/src/handlers/replace_if_let_with_match.rs
@@ -10,7 +10,10 @@ use syntax::{
     AstNode,
 };
 
-use crate::{utils::unwrap_trivial_block, AssistContext, AssistId, AssistKind, Assists};
+use crate::{
+    utils::{does_pat_match_variant, unwrap_trivial_block},
+    AssistContext, AssistId, AssistKind, Assists,
+};
 
 // Assist: replace_if_let_with_match
 //
@@ -66,7 +69,13 @@ pub(crate) fn replace_if_let_with_match(acc: &mut Assists, ctx: &AssistContext)
                         .sema
                         .type_of_pat(&pat)
                         .and_then(|ty| TryEnum::from_ty(&ctx.sema, &ty))
-                        .map(|it| it.sad_pattern())
+                        .map(|it| {
+                            if does_pat_match_variant(&pat, &it.sad_pattern()) {
+                                it.happy_pattern()
+                            } else {
+                                it.sad_pattern()
+                            }
+                        })
                         .unwrap_or_else(|| make::wildcard_pat().into());
                     let else_expr = unwrap_trivial_block(else_block);
                     make::match_arm(vec![pattern], else_expr)
@@ -279,6 +288,36 @@ fn foo(x: Option<i32>) {
     }
 
     #[test]
+    fn special_case_inverted_option() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    $0if let None = x {
+        println!("none")
+    } else {
+        println!("some")
+    }
+}
+           "#,
+            r#"
+enum Option<T> { Some(T), None }
+use Option::*;
+
+fn foo(x: Option<i32>) {
+    match x {
+        None => println!("none"),
+        Some(_) => println!("some"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
     fn special_case_result() {
         check_assist(
             replace_if_let_with_match,
@@ -309,6 +348,36 @@ fn foo(x: Result<i32, ()>) {
     }
 
     #[test]
+    fn special_case_inverted_result() {
+        check_assist(
+            replace_if_let_with_match,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    $0if let Err(x) = x {
+        println!("{}", x)
+    } else {
+        println!("ok")
+    }
+}
+           "#,
+            r#"
+enum Result<T, E> { Ok(T), Err(E) }
+use Result::*;
+
+fn foo(x: Result<i32, ()>) {
+    match x {
+        Err(x) => println!("{}", x),
+        Ok(_) => println!("ok"),
+    }
+}
+           "#,
+        );
+    }
+
+    #[test]
     fn nested_indent() {
         check_assist(
             replace_if_let_with_match,
diff --git a/crates/assists/src/utils.rs b/crates/assists/src/utils.rs
index 44c35bafa..4e762e18b 100644
--- a/crates/assists/src/utils.rs
+++ b/crates/assists/src/utils.rs
@@ -248,3 +248,22 @@ fn invert_special_case(expr: &ast::Expr) -> Option<ast::Expr> {
 pub(crate) fn next_prev() -> impl Iterator<Item = Direction> {
     [Direction::Next, Direction::Prev].iter().copied()
 }
+
+pub(crate) fn does_pat_match_variant(pat: &ast::Pat, var: &ast::Pat) -> bool {
+    let first_node_text = |pat: &ast::Pat| pat.syntax().first_child().map(|node| node.text());
+
+    let pat_head = match pat {
+        ast::Pat::IdentPat(bind_pat) => {
+            if let Some(p) = bind_pat.pat() {
+                first_node_text(&p)
+            } else {
+                return pat.syntax().text() == var.syntax().text();
+            }
+        }
+        pat => first_node_text(pat),
+    };
+
+    let var_head = first_node_text(var);
+
+    pat_head == var_head
+}
diff --git a/crates/hir_def/src/db.rs b/crates/hir_def/src/db.rs
index a87c80b8a..aef7e1f6c 100644
--- a/crates/hir_def/src/db.rs
+++ b/crates/hir_def/src/db.rs
@@ -2,9 +2,9 @@
 use std::sync::Arc;
 
 use base_db::{salsa, CrateId, SourceDatabase, Upcast};
-use hir_expand::{db::AstDatabase, AstId, HirFileId};
+use hir_expand::{db::AstDatabase, HirFileId};
 use la_arena::ArenaMap;
-use syntax::{ast, SmolStr};
+use syntax::SmolStr;
 
 use crate::{
     adt::{EnumData, StructData},
@@ -16,9 +16,10 @@ use crate::{
     item_tree::ItemTree,
     lang_item::{LangItemTarget, LangItems},
     nameres::DefMap,
-    AttrDefId, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, FunctionId, FunctionLoc,
-    GenericDefId, ImplId, ImplLoc, LocalEnumVariantId, LocalFieldId, StaticId, StaticLoc, StructId,
-    StructLoc, TraitId, TraitLoc, TypeAliasId, TypeAliasLoc, UnionId, UnionLoc, VariantId,
+    AttrDefId, BlockId, BlockLoc, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, FunctionId,
+    FunctionLoc, GenericDefId, ImplId, ImplLoc, LocalEnumVariantId, LocalFieldId, StaticId,
+    StaticLoc, StructId, StructLoc, TraitId, TraitLoc, TypeAliasId, TypeAliasLoc, UnionId,
+    UnionLoc, VariantId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -41,6 +42,8 @@ pub trait InternDatabase: SourceDatabase {
     fn intern_type_alias(&self, loc: TypeAliasLoc) -> TypeAliasId;
     #[salsa::interned]
     fn intern_impl(&self, loc: ImplLoc) -> ImplId;
+    #[salsa::interned]
+    fn intern_block(&self, loc: BlockLoc) -> BlockId;
 }
 
 #[salsa::query_group(DefDatabaseStorage)]
@@ -56,7 +59,7 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     fn crate_def_map_query(&self, krate: CrateId) -> Arc<DefMap>;
 
     #[salsa::invoke(DefMap::block_def_map_query)]
-    fn block_def_map(&self, krate: CrateId, block: AstId<ast::BlockExpr>) -> Arc<DefMap>;
+    fn block_def_map(&self, block: BlockId) -> Arc<DefMap>;
 
     #[salsa::invoke(StructData::struct_data_query)]
     fn struct_data(&self, id: StructId) -> Arc<StructData>;
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index cf09ebd3f..42b50b5b7 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -74,12 +74,16 @@ use stdx::impl_from;
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct ModuleId {
     krate: CrateId,
+    block: Option<BlockId>,
     pub local_id: LocalModuleId,
 }
 
 impl ModuleId {
     pub fn def_map(&self, db: &dyn db::DefDatabase) -> Arc<DefMap> {
-        db.crate_def_map(self.krate)
+        match self.block {
+            Some(block) => db.block_def_map(block),
+            None => db.crate_def_map(self.krate),
+        }
     }
 
     pub fn krate(&self) -> CrateId {
@@ -230,6 +234,15 @@ pub struct ImplId(salsa::InternId);
 type ImplLoc = ItemLoc<Impl>;
 impl_intern!(ImplId, ImplLoc, intern_impl, lookup_intern_impl);
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Ord, PartialOrd)]
+pub struct BlockId(salsa::InternId);
+#[derive(Debug, Hash, PartialEq, Eq, Clone)]
+pub struct BlockLoc {
+    ast_id: AstId<ast::BlockExpr>,
+    module: ModuleId,
+}
+impl_intern!(BlockId, BlockLoc, intern_block, lookup_intern_block);
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct TypeParamId {
     pub parent: GenericDefId,
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index 4fbbecb38..199771e9a 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -62,7 +62,7 @@ use la_arena::Arena;
 use profile::Count;
 use rustc_hash::FxHashMap;
 use stdx::format_to;
-use syntax::{ast, AstNode};
+use syntax::ast;
 
 use crate::{
     db::DefDatabase,
@@ -70,14 +70,14 @@ use crate::{
     nameres::{diagnostics::DefDiagnostic, path_resolution::ResolveMode},
     path::ModPath,
     per_ns::PerNs,
-    AstId, LocalModuleId, ModuleDefId, ModuleId,
+    AstId, BlockId, BlockLoc, LocalModuleId, ModuleDefId, ModuleId,
 };
 
 /// Contains all top-level defs from a macro-expanded crate
 #[derive(Debug, PartialEq, Eq)]
 pub struct DefMap {
     _c: Count<Self>,
-    parent: Option<Arc<DefMap>>,
+    block: Option<BlockInfo>,
     root: LocalModuleId,
     modules: Arena<ModuleData>,
     krate: CrateId,
@@ -91,6 +91,13 @@ pub struct DefMap {
     diagnostics: Vec<DefDiagnostic>,
 }
 
+#[derive(Debug, PartialEq, Eq)]
+struct BlockInfo {
+    block: BlockId,
+    parent: Arc<DefMap>,
+    parent_module: LocalModuleId,
+}
+
 impl std::ops::Index<LocalModuleId> for DefMap {
     type Output = ModuleData;
     fn index(&self, id: LocalModuleId) -> &ModuleData {
@@ -190,15 +197,12 @@ impl DefMap {
         Arc::new(def_map)
     }
 
-    pub(crate) fn block_def_map_query(
-        db: &dyn DefDatabase,
-        krate: CrateId,
-        block: AstId<ast::BlockExpr>,
-    ) -> Arc<DefMap> {
-        let item_tree = db.item_tree(block.file_id);
-        let block_items = item_tree.inner_items_of_block(block.value);
+    pub(crate) fn block_def_map_query(db: &dyn DefDatabase, block_id: BlockId) -> Arc<DefMap> {
+        let block: BlockLoc = db.lookup_intern_block(block_id);
+        let item_tree = db.item_tree(block.ast_id.file_id);
+        let block_items = item_tree.inner_items_of_block(block.ast_id.value);
 
-        let parent = parent_def_map(db, krate, block);
+        let parent = block.module.def_map(db);
 
         if block_items.is_empty() {
             // If there are no inner items, nothing new is brought into scope, so we can just return
@@ -206,10 +210,13 @@ impl DefMap {
             return parent;
         }
 
-        let mut def_map = DefMap::empty(krate, parent.edition);
-        def_map.parent = Some(parent);
+        let block_info =
+            BlockInfo { block: block_id, parent, parent_module: block.module.local_id };
+
+        let mut def_map = DefMap::empty(block.module.krate, block_info.parent.edition);
+        def_map.block = Some(block_info);
 
-        let def_map = collector::collect_defs(db, def_map, Some(block.value));
+        let def_map = collector::collect_defs(db, def_map, Some(block.ast_id.value));
         Arc::new(def_map)
     }
 
@@ -218,7 +225,7 @@ impl DefMap {
         let root = modules.alloc(ModuleData::default());
         DefMap {
             _c: Count::new(),
-            parent: None,
+            block: None,
             krate,
             edition,
             extern_prelude: FxHashMap::default(),
@@ -266,7 +273,8 @@ impl DefMap {
     }
 
     pub fn module_id(&self, local_id: LocalModuleId) -> ModuleId {
-        ModuleId { krate: self.krate, local_id }
+        let block = self.block.as_ref().map(|b| b.block);
+        ModuleId { krate: self.krate, local_id, block }
     }
 
     pub(crate) fn resolve_path(
@@ -286,9 +294,9 @@ impl DefMap {
     pub fn dump(&self) -> String {
         let mut buf = String::new();
         let mut current_map = self;
-        while let Some(parent) = &current_map.parent {
+        while let Some(block) = &current_map.block {
             go(&mut buf, current_map, "block scope", current_map.root);
-            current_map = &**parent;
+            current_map = &*block.parent;
         }
         go(&mut buf, current_map, "crate", current_map.root);
         return buf;
@@ -342,35 +350,6 @@ impl ModuleData {
     }
 }
 
-fn parent_def_map(
-    db: &dyn DefDatabase,
-    krate: CrateId,
-    block: AstId<ast::BlockExpr>,
-) -> Arc<DefMap> {
-    // FIXME: store this info in the item tree instead of reparsing here
-    let ast_id_map = db.ast_id_map(block.file_id);
-    let block_ptr = ast_id_map.get(block.value);
-    let root = match db.parse_or_expand(block.file_id) {
-        Some(it) => it,
-        None => {
-            return Arc::new(DefMap::empty(krate, Edition::Edition2018));
-        }
-    };
-    let ast = block_ptr.to_node(&root);
-
-    for ancestor in ast.syntax().ancestors().skip(1) {
-        if let Some(block_expr) = ast::BlockExpr::cast(ancestor) {
-            let ancestor_id = ast_id_map.ast_id(&block_expr);
-            let ast_id = InFile::new(block.file_id, ancestor_id);
-            let parent_map = db.block_def_map(krate, ast_id);
-            return parent_map;
-        }
-    }
-
-    // No enclosing block scope, so the parent is the crate-level DefMap.
-    db.crate_def_map(krate)
-}
-
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ModuleSource {
     SourceFile(ast::SourceFile),
diff --git a/crates/hir_def/src/nameres/path_resolution.rs b/crates/hir_def/src/nameres/path_resolution.rs
index c1eded5f2..419e465ed 100644
--- a/crates/hir_def/src/nameres/path_resolution.rs
+++ b/crates/hir_def/src/nameres/path_resolution.rs
@@ -10,8 +10,6 @@
 //!
 //! `ReachedFixedPoint` signals about this.
 
-use std::iter::successors;
-
 use base_db::Edition;
 use hir_expand::name;
 use hir_expand::name::Name;
@@ -131,8 +129,8 @@ impl DefMap {
             result.krate = result.krate.or(new.krate);
             result.segment_index = result.segment_index.min(new.segment_index);
 
-            match &current_map.parent {
-                Some(map) => current_map = map,
+            match &current_map.block {
+                Some(block) => current_map = &block.parent,
                 None => return result,
             }
         }
@@ -193,14 +191,35 @@ impl DefMap {
                 self.resolve_name_in_module(db, original_module, &segment, prefer_module)
             }
             PathKind::Super(lvl) => {
-                let m = successors(Some(original_module), |m| self.modules[*m].parent)
-                    .nth(lvl as usize);
-                if let Some(local_id) = m {
-                    PerNs::types(self.module_id(local_id).into(), Visibility::Public)
-                } else {
-                    log::debug!("super path in root module");
-                    return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                let mut module = original_module;
+                for i in 0..lvl {
+                    match self.modules[module].parent {
+                        Some(it) => module = it,
+                        None => match &self.block {
+                            Some(block) => {
+                                // Look up remaining path in parent `DefMap`
+                                let new_path = ModPath {
+                                    kind: PathKind::Super(lvl - i),
+                                    segments: path.segments.clone(),
+                                };
+                                log::debug!("`super` path: {} -> {} in parent map", path, new_path);
+                                return block.parent.resolve_path_fp_with_macro(
+                                    db,
+                                    mode,
+                                    block.parent_module,
+                                    &new_path,
+                                    shadow,
+                                );
+                            }
+                            None => {
+                                log::debug!("super path in root module");
+                                return ResolvePathResult::empty(ReachedFixedPoint::Yes);
+                            }
+                        },
+                    }
                 }
+
+                PerNs::types(self.module_id(module).into(), Visibility::Public)
             }
             PathKind::Abs => {
                 // 2018-style absolute path -- only extern prelude
diff --git a/crates/hir_def/src/nameres/tests.rs b/crates/hir_def/src/nameres/tests.rs
index 73e3a4702..b36d0b59b 100644
--- a/crates/hir_def/src/nameres/tests.rs
+++ b/crates/hir_def/src/nameres/tests.rs
@@ -8,12 +8,12 @@ mod block;
 
 use std::sync::Arc;
 
-use base_db::{fixture::WithFixture, SourceDatabase};
+use base_db::{fixture::WithFixture, FilePosition, SourceDatabase};
 use expect_test::{expect, Expect};
-use hir_expand::db::AstDatabase;
+use syntax::AstNode;
 use test_utils::mark;
 
-use crate::{db::DefDatabase, nameres::*, test_db::TestDB};
+use crate::{db::DefDatabase, nameres::*, test_db::TestDB, Lookup};
 
 fn compute_crate_def_map(ra_fixture: &str) -> Arc<DefMap> {
     let db = TestDB::with_files(ra_fixture);
@@ -23,14 +23,58 @@ fn compute_crate_def_map(ra_fixture: &str) -> Arc<DefMap> {
 
 fn compute_block_def_map(ra_fixture: &str) -> Arc<DefMap> {
     let (db, position) = TestDB::with_position(ra_fixture);
+
+    // FIXME: perhaps we should make this use body lowering tests instead?
+
     let module = db.module_for_file(position.file_id);
-    let ast_map = db.ast_id_map(position.file_id.into());
-    let ast = db.parse(position.file_id);
-    let block: ast::BlockExpr =
-        syntax::algo::find_node_at_offset(&ast.syntax_node(), position.offset).unwrap();
-    let block_id = ast_map.ast_id(&block);
+    let mut def_map = db.crate_def_map(module.krate);
+    while let Some(new_def_map) = descend_def_map_at_position(&db, position, def_map.clone()) {
+        def_map = new_def_map;
+    }
+
+    // FIXME: select the right module, not the root
+
+    def_map
+}
+
+fn descend_def_map_at_position(
+    db: &dyn DefDatabase,
+    position: FilePosition,
+    def_map: Arc<DefMap>,
+) -> Option<Arc<DefMap>> {
+    for (local_id, module_data) in def_map.modules() {
+        let mod_def = module_data.origin.definition_source(db);
+        let ast_map = db.ast_id_map(mod_def.file_id);
+        let item_tree = db.item_tree(mod_def.file_id);
+        let root = db.parse_or_expand(mod_def.file_id).unwrap();
+        for item in module_data.scope.declarations() {
+            match item {
+                ModuleDefId::FunctionId(it) => {
+                    // Technically blocks can be inside any type (due to arrays and const generics),
+                    // and also in const/static initializers. For tests we only really care about
+                    // functions though.
+
+                    let ast = ast_map.get(item_tree[it.lookup(db).id.value].ast_id).to_node(&root);
+
+                    if ast.syntax().text_range().contains(position.offset) {
+                        // Cursor inside function, descend into its body's DefMap.
+                        // Note that we don't handle block *expressions* inside function bodies.
+                        let ast_map = db.ast_id_map(position.file_id.into());
+                        let ast_id = ast_map.ast_id(&ast.body().unwrap());
+                        let block = BlockLoc {
+                            ast_id: InFile::new(position.file_id.into(), ast_id),
+                            module: def_map.module_id(local_id),
+                        };
+                        let block_id = db.intern_block(block);
+                        return Some(db.block_def_map(block_id));
+                    }
+                }
+                _ => continue,
+            }
+        }
+    }
 
-    db.block_def_map(module.krate, InFile::new(position.file_id.into(), block_id))
+    None
 }
 
 fn check(ra_fixture: &str, expect: Expect) {
diff --git a/crates/hir_def/src/nameres/tests/block.rs b/crates/hir_def/src/nameres/tests/block.rs
index 01d6326a7..470ca593e 100644
--- a/crates/hir_def/src/nameres/tests/block.rs
+++ b/crates/hir_def/src/nameres/tests/block.rs
@@ -95,3 +95,29 @@ fn outer() {
         "#]],
     );
 }
+
+#[test]
+fn super_imports() {
+    check_at(
+        r#"
+mod module {
+    fn f() {
+        use super::Struct;
+        $0
+    }
+}
+
+struct Struct {}
+"#,
+        expect![[r#"
+            block scope
+            Struct: t
+            crate
+            Struct: t
+            module: t
+
+            crate::module
+            f: v
+        "#]],
+    );
+}
diff --git a/crates/ide/src/display/navigation_target.rs b/crates/ide/src/display/navigation_target.rs
index f178dd744..23d885218 100644
--- a/crates/ide/src/display/navigation_target.rs
+++ b/crates/ide/src/display/navigation_target.rs
@@ -435,13 +435,16 @@ impl TryToNav for hir::TypeParam {
     fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
         let src = self.source(db)?;
         let full_range = match &src.value {
-            Either::Left(it) => it.syntax().text_range(),
+            Either::Left(it) => it
+                .name()
+                .map_or_else(|| it.syntax().text_range(), |name| name.syntax().text_range()),
             Either::Right(it) => it.syntax().text_range(),
         };
         let focus_range = match &src.value {
-            Either::Left(_) => None,
-            Either::Right(it) => it.name().map(|it| it.syntax().text_range()),
-        };
+            Either::Left(it) => it.name(),
+            Either::Right(it) => it.name(),
+        }
+        .map(|it| it.syntax().text_range());
         Some(NavigationTarget {
             file_id: src.file_id.original_file(db),
             name: self.name(db).to_string().into(),
diff --git a/crates/ide/src/references.rs b/crates/ide/src/references.rs
index 3a4f4d80b..40d9487eb 100644
--- a/crates/ide/src/references.rs
+++ b/crates/ide/src/references.rs
@@ -1098,4 +1098,20 @@ fn foo<const FOO$0: usize>() -> usize {
             "#]],
         );
     }
+
+    #[test]
+    fn test_find_self_ty_in_trait_def() {
+        check(
+            r#"
+trait Foo {
+    fn f() -> Self$0;
+}
+"#,
+            expect![[r#"
+                Self TypeParam FileId(0) 6..9 6..9 Other
+
+                FileId(0) 26..30 Other
+            "#]],
+        );
+    }
 }
diff --git a/crates/ide_db/src/ty_filter.rs b/crates/ide_db/src/ty_filter.rs
index 63a945282..f8406851b 100644
--- a/crates/ide_db/src/ty_filter.rs
+++ b/crates/ide_db/src/ty_filter.rs
@@ -49,6 +49,21 @@ impl TryEnum {
         }
     }
 
+    pub fn happy_pattern(self) -> ast::Pat {
+        match self {
+            TryEnum::Result => make::tuple_struct_pat(
+                make::path_unqualified(make::path_segment(make::name_ref("Ok"))),
+                iter::once(make::wildcard_pat().into()),
+            )
+            .into(),
+            TryEnum::Option => make::tuple_struct_pat(
+                make::path_unqualified(make::path_segment(make::name_ref("Some"))),
+                iter::once(make::wildcard_pat().into()),
+            )
+            .into(),
+        }
+    }
+
     fn type_name(self) -> &'static str {
         match self {
             TryEnum::Result => "Result",
diff --git a/crates/paths/src/lib.rs b/crates/paths/src/lib.rs
index 1b259682d..22011cb33 100644
--- a/crates/paths/src/lib.rs
+++ b/crates/paths/src/lib.rs
@@ -6,6 +6,7 @@ use std::{
     path::{Component, Path, PathBuf},
 };
 
+/// Wrapper around an absolute [`PathBuf`].
 #[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
 pub struct AbsPathBuf(PathBuf);
 
@@ -58,18 +59,33 @@ impl PartialEq<AbsPath> for AbsPathBuf {
 }
 
 impl AbsPathBuf {
+    /// Wrap the given absolute path in `AbsPathBuf`
+    ///
+    /// # Panics
+    ///
+    /// Panics if `path` is not absolute.
     pub fn assert(path: PathBuf) -> AbsPathBuf {
         AbsPathBuf::try_from(path)
             .unwrap_or_else(|path| panic!("expected absolute path, got {}", path.display()))
     }
+
+    /// Coerces to a `AbsPath` slice.
+    ///
+    /// Equivalent of [`PathBuf::as_path`] for `AbsPathBuf`.
     pub fn as_path(&self) -> &AbsPath {
         AbsPath::assert(self.0.as_path())
     }
+
+    /// Equivalent of [`PathBuf::pop`] for `AbsPathBuf`.
+    ///
+    /// Note that this won't remove the root component, so `self` will still be
+    /// absolute.
     pub fn pop(&mut self) -> bool {
         self.0.pop()
     }
 }
 
+/// Wrapper around an absolute [`Path`].
 #[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Hash)]
 #[repr(transparent)]
 pub struct AbsPath(Path);
@@ -98,28 +114,56 @@ impl<'a> TryFrom<&'a Path> for &'a AbsPath {
 }
 
 impl AbsPath {
+    /// Wrap the given absolute path in `AbsPath`
+    ///
+    /// # Panics
+    ///
+    /// Panics if `path` is not absolute.
     pub fn assert(path: &Path) -> &AbsPath {
         assert!(path.is_absolute());
         unsafe { &*(path as *const Path as *const AbsPath) }
     }
 
+    /// Equivalent of [`Path::parent`] for `AbsPath`.
     pub fn parent(&self) -> Option<&AbsPath> {
         self.0.parent().map(AbsPath::assert)
     }
+
+    /// Equivalent of [`Path::join`] for `AbsPath`.
     pub fn join(&self, path: impl AsRef<Path>) -> AbsPathBuf {
         self.as_ref().join(path).try_into().unwrap()
     }
+
+    /// Normalize the given path:
+    /// - Removes repeated separators: `/a//b` becomes `/a/b`
+    /// - Removes occurrences of `.` and resolves `..`.
+    /// - Removes trailing slashes: `/a/b/` becomes `/a/b`.
+    ///
+    /// # Example
+    /// ```
+    /// # use paths::AbsPathBuf;
+    /// let abs_path_buf = AbsPathBuf::assert("/a/../../b/.//c//".into());
+    /// let normalized = abs_path_buf.normalize();
+    /// assert_eq!(normalized, AbsPathBuf::assert("/b/c".into()));
+    /// ```
     pub fn normalize(&self) -> AbsPathBuf {
         AbsPathBuf(normalize_path(&self.0))
     }
+
+    /// Equivalent of [`Path::to_path_buf`] for `AbsPath`.
     pub fn to_path_buf(&self) -> AbsPathBuf {
         AbsPathBuf::try_from(self.0.to_path_buf()).unwrap()
     }
+
+    /// Equivalent of [`Path::strip_prefix`] for `AbsPath`.
+    ///
+    /// Returns a relative path.
     pub fn strip_prefix(&self, base: &AbsPath) -> Option<&RelPath> {
         self.0.strip_prefix(base).ok().map(RelPath::new_unchecked)
     }
 }
 
+/// Wrapper around a relative [`PathBuf`].
 #[derive(Debug, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
 pub struct RelPathBuf(PathBuf);
 
@@ -160,11 +204,15 @@ impl TryFrom<&str> for RelPathBuf {
 }
 
 impl RelPathBuf {
+    /// Coerces to a `RelPath` slice.
+    ///
+    /// Equivalent of [`PathBuf::as_path`] for `RelPathBuf`.
     pub fn as_path(&self) -> &RelPath {
         RelPath::new_unchecked(self.0.as_path())
     }
 }
 
+/// Wrapper around a relative [`Path`].
 #[derive(Debug, Ord, PartialOrd, Eq, PartialEq, Hash)]
 #[repr(transparent)]
 pub struct RelPath(Path);
@@ -183,12 +231,13 @@ impl AsRef<Path> for RelPath {
 }
 
 impl RelPath {
+    /// Creates a new `RelPath` from `path`, without checking if it is relative.
     pub fn new_unchecked(path: &Path) -> &RelPath {
         unsafe { &*(path as *const Path as *const RelPath) }
     }
 }
 
-// https://github.com/rust-lang/cargo/blob/79c769c3d7b4c2cf6a93781575b7f592ef974255/src/cargo/util/paths.rs#L60-L85
+/// Taken from https://github.com/rust-lang/cargo/blob/79c769c3d7b4c2cf6a93781575b7f592ef974255/src/cargo/util/paths.rs#L60-L85
 fn normalize_path(path: &Path) -> PathBuf {
     let mut components = path.components().peekable();
     let mut ret = if let Some(c @ Component::Prefix(..)) = components.peek().cloned() {
diff --git a/docs/dev/README.md b/docs/dev/README.md
index 6a6ba1443..6bce38e56 100644
--- a/docs/dev/README.md
+++ b/docs/dev/README.md
@@ -43,6 +43,10 @@ https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0
   while unactionable ones are effectively wont-fix. Each triaged issue should have one of these labels.
 * [fun](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%3Afun)
   is for cool, but probably hard stuff.
+* [Design](https://github.com/rust-analyzer/rust-analyzer/issues?q=is%3Aopen+is%3Aissue+label%Design)
+  is for moderate/large scale architecture discussion.
+  Also a kind of fun.
+  These issues should generally include a link to a Zulip discussion thread.
 
 # CI
 
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 1edb7713d..1900d900a 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -208,7 +208,6 @@ async function bootstrapExtension(config: Config, state: PersistentState): Promi
             url: artifact.browser_download_url,
             dest,
             progressTitle: "Downloading rust-analyzer extension",
-            overwrite: true,
         });
     });
 
@@ -340,7 +339,6 @@ async function getServer(config: Config, state: PersistentState): Promise<string
             progressTitle: "Downloading rust-analyzer server",
             gunzip: true,
             mode: 0o755,
-            overwrite: true,
         });
     });
 
diff --git a/editors/code/src/net.ts b/editors/code/src/net.ts
index 3e50d352c..d39dc1baf 100644
--- a/editors/code/src/net.ts
+++ b/editors/code/src/net.ts
@@ -73,23 +73,16 @@ interface DownloadOpts {
     dest: string;
     mode?: number;
     gunzip?: boolean;
-    overwrite?: boolean;
 }
 
 export async function download(opts: DownloadOpts) {
     // Put artifact into a temporary file (in the same dir for simplicity)
     // to prevent partially downloaded files when user kills vscode
+    // This also avoids overwriting running executables
     const dest = path.parse(opts.dest);
     const randomHex = crypto.randomBytes(5).toString("hex");
     const tempFile = path.join(dest.dir, `${dest.name}${randomHex}`);
 
-    if (opts.overwrite) {
-        // Unlinking the exe file before moving new one on its place should prevent ETXTBSY error.
-        await fs.promises.unlink(opts.dest).catch(err => {
-            if (err.code !== "ENOENT") throw err;
-        });
-    }
-
     await vscode.window.withProgress(
         {
             location: vscode.ProgressLocation.Notification,