Merging upstream version 1.69.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

38 files changed, 738 insertions, 837 deletions

diff --git a/src/tools/rust-analyzer/crates/hir-def/Cargo.toml b/src/tools/rust-analyzer/crates/hir-def/Cargo.toml
index 698be7665..31d4018d2 100644
--- a/src/tools/rust-analyzer/crates/hir-def/Cargo.toml
+++ b/src/tools/rust-analyzer/crates/hir-def/Cargo.toml
@@ -2,9 +2,11 @@
 name = "hir-def"
 version = "0.0.0"
 description = "TBD"
-license = "MIT OR Apache-2.0"
-edition = "2021"
-rust-version = "1.65"
+
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+rust-version.workspace = true
 
 [lib]
 doctest = false
@@ -23,23 +25,28 @@ hashbrown = { version = "0.12.1", default-features = false }
 indexmap = "1.9.1"
 itertools = "0.10.5"
 la-arena = { version = "0.3.0", path = "../../lib/la-arena" }
-once_cell = "1.15.0"
+once_cell = "1.17.0"
 rustc-hash = "1.1.0"
-smallvec = "1.10.0"
+smallvec.workspace = true
 tracing = "0.1.35"
 
-stdx = { path = "../stdx", version = "0.0.0" }
-base-db = { path = "../base-db", version = "0.0.0" }
-syntax = { path = "../syntax", version = "0.0.0" }
-profile = { path = "../profile", version = "0.0.0" }
-hir-expand = { path = "../hir-expand", version = "0.0.0" }
 rustc_abi = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_abi", default-features = false }
 rustc_index = { version = "0.0.20221221", package = "hkalbasi-rustc-ap-rustc_index", default-features = false }
-mbe = { path = "../mbe", version = "0.0.0" }
-cfg = { path = "../cfg", version = "0.0.0" }
-tt = { path = "../tt", version = "0.0.0" }
-limit = { path = "../limit", version = "0.0.0" }
+
+# local deps
+stdx.workspace = true
+intern.workspace = true
+base-db.workspace = true
+syntax.workspace = true
+profile.workspace = true
+hir-expand.workspace = true
+mbe.workspace = true
+cfg.workspace = true
+tt.workspace = true
+limit.workspace = true
 
 [dev-dependencies]
-test-utils = { path = "../test-utils" }
 expect-test = "1.4.0"
+
+# local deps
+test-utils.workspace = true
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/adt.rs b/src/tools/rust-analyzer/crates/hir-def/src/adt.rs
index db3b41948..9bc1c54a3 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/adt.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/adt.rs
@@ -3,33 +3,34 @@
 use std::sync::Arc;
 
 use base_db::CrateId;
+use cfg::CfgOptions;
 use either::Either;
+
 use hir_expand::{
     name::{AsName, Name},
     HirFileId, InFile,
 };
+use intern::Interned;
 use la_arena::{Arena, ArenaMap};
 use rustc_abi::{Integer, IntegerType};
 use syntax::ast::{self, HasName, HasVisibility};
-use tt::{Delimiter, DelimiterKind, Leaf, Subtree, TokenTree};
 
 use crate::{
     body::{CfgExpander, LowerCtx},
     builtin_type::{BuiltinInt, BuiltinUint},
     db::DefDatabase,
-    intern::Interned,
     item_tree::{AttrOwner, Field, FieldAstId, Fields, ItemTree, ModItem, RawVisibilityId},
     layout::{Align, ReprFlags, ReprOptions},
     nameres::diagnostics::DefDiagnostic,
     src::HasChildSource,
     src::HasSource,
     trace::Trace,
+    tt::{Delimiter, DelimiterKind, Leaf, Subtree, TokenTree},
     type_ref::TypeRef,
     visibility::RawVisibility,
     EnumId, LocalEnumVariantId, LocalFieldId, LocalModuleId, Lookup, ModuleId, StructId, UnionId,
     VariantId,
 };
-use cfg::CfgOptions;
 
 /// Note that we use `StructData` for unions as well!
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -82,7 +83,7 @@ fn repr_from_value(
 
 fn parse_repr_tt(tt: &Subtree) -> Option<ReprOptions> {
     match tt.delimiter {
-        Some(Delimiter { kind: DelimiterKind::Parenthesis, .. }) => {}
+        Delimiter { kind: DelimiterKind::Parenthesis, .. } => {}
         _ => return None,
     }
 
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/attr.rs b/src/tools/rust-analyzer/crates/hir-def/src/attr.rs
index ab5d180e1..fcd92ad33 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/attr.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/attr.rs
@@ -1,27 +1,26 @@
 //! A higher level attributes based on TokenTree, with also some shortcuts.
 
-use std::{fmt, hash::Hash, ops, sync::Arc};
+use std::{hash::Hash, ops, sync::Arc};
 
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use either::Either;
-use hir_expand::{hygiene::Hygiene, name::AsName, HirFileId, InFile};
+use hir_expand::{
+    attrs::{collect_attrs, Attr, AttrId, RawAttrs},
+    HirFileId, InFile,
+};
 use itertools::Itertools;
 use la_arena::{ArenaMap, Idx, RawIdx};
-use mbe::{syntax_node_to_token_tree, DelimiterKind, Punct};
-use smallvec::{smallvec, SmallVec};
+use mbe::DelimiterKind;
 use syntax::{
-    ast::{self, AstNode, HasAttrs, IsString},
-    match_ast, AstPtr, AstToken, SmolStr, SyntaxNode, TextRange, TextSize,
+    ast::{self, HasAttrs, IsString},
+    AstPtr, AstToken, SmolStr, TextRange, TextSize,
 };
-use tt::Subtree;
 
 use crate::{
     db::DefDatabase,
-    intern::Interned,
     item_tree::{AttrOwner, Fields, ItemTreeId, ItemTreeNode},
     nameres::{ModuleOrigin, ModuleSource},
-    path::{ModPath, PathKind},
     src::{HasChildSource, HasSource},
     AdtId, AttrDefId, EnumId, GenericParamId, LocalEnumVariantId, LocalFieldId, Lookup, MacroId,
     VariantId,
@@ -47,12 +46,6 @@ impl From<Documentation> for String {
     }
 }
 
-/// Syntactical attributes, without filtering of `cfg_attr`s.
-#[derive(Default, Debug, Clone, PartialEq, Eq)]
-pub(crate) struct RawAttrs {
-    entries: Option<Arc<[Attr]>>,
-}
-
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct Attrs(RawAttrs);
 
@@ -62,30 +55,21 @@ pub struct AttrsWithOwner {
     owner: AttrDefId,
 }
 
-impl ops::Deref for RawAttrs {
-    type Target = [Attr];
-
-    fn deref(&self) -> &[Attr] {
-        match &self.entries {
-            Some(it) => &*it,
-            None => &[],
-        }
-    }
-}
 impl Attrs {
     pub fn get(&self, id: AttrId) -> Option<&Attr> {
         (**self).iter().find(|attr| attr.id == id)
     }
+
+    pub(crate) fn filter(db: &dyn DefDatabase, krate: CrateId, raw_attrs: RawAttrs) -> Attrs {
+        Attrs(raw_attrs.filter(db.upcast(), krate))
+    }
 }
 
 impl ops::Deref for Attrs {
     type Target = [Attr];
 
     fn deref(&self) -> &[Attr] {
-        match &self.0.entries {
-            Some(it) => &*it,
-            None => &[],
-        }
+        &self.0
     }
 }
 
@@ -97,114 +81,6 @@ impl ops::Deref for AttrsWithOwner {
     }
 }
 
-impl RawAttrs {
-    pub(crate) const EMPTY: Self = Self { entries: None };
-
-    pub(crate) fn new(db: &dyn DefDatabase, owner: &dyn ast::HasAttrs, hygiene: &Hygiene) -> Self {
-        let entries = collect_attrs(owner)
-            .filter_map(|(id, attr)| match attr {
-                Either::Left(attr) => {
-                    attr.meta().and_then(|meta| Attr::from_src(db, meta, hygiene, id))
-                }
-                Either::Right(comment) => comment.doc_comment().map(|doc| Attr {
-                    id,
-                    input: Some(Interned::new(AttrInput::Literal(SmolStr::new(doc)))),
-                    path: Interned::new(ModPath::from(hir_expand::name!(doc))),
-                }),
-            })
-            .collect::<Arc<_>>();
-
-        Self { entries: if entries.is_empty() { None } else { Some(entries) } }
-    }
-
-    fn from_attrs_owner(db: &dyn DefDatabase, owner: InFile<&dyn ast::HasAttrs>) -> Self {
-        let hygiene = Hygiene::new(db.upcast(), owner.file_id);
-        Self::new(db, owner.value, &hygiene)
-    }
-
-    pub(crate) fn merge(&self, other: Self) -> Self {
-        // FIXME: This needs to fixup `AttrId`s
-        match (&self.entries, other.entries) {
-            (None, None) => Self::EMPTY,
-            (None, entries @ Some(_)) => Self { entries },
-            (Some(entries), None) => Self { entries: Some(entries.clone()) },
-            (Some(a), Some(b)) => {
-                let last_ast_index = a.last().map_or(0, |it| it.id.ast_index + 1);
-                Self {
-                    entries: Some(
-                        a.iter()
-                            .cloned()
-                            .chain(b.iter().map(|it| {
-                                let mut it = it.clone();
-                                it.id.ast_index += last_ast_index;
-                                it
-                            }))
-                            .collect(),
-                    ),
-                }
-            }
-        }
-    }
-
-    /// Processes `cfg_attr`s, returning the resulting semantic `Attrs`.
-    pub(crate) fn filter(self, db: &dyn DefDatabase, krate: CrateId) -> Attrs {
-        let has_cfg_attrs = self.iter().any(|attr| {
-            attr.path.as_ident().map_or(false, |name| *name == hir_expand::name![cfg_attr])
-        });
-        if !has_cfg_attrs {
-            return Attrs(self);
-        }
-
-        let crate_graph = db.crate_graph();
-        let new_attrs = self
-            .iter()
-            .flat_map(|attr| -> SmallVec<[_; 1]> {
-                let is_cfg_attr =
-                    attr.path.as_ident().map_or(false, |name| *name == hir_expand::name![cfg_attr]);
-                if !is_cfg_attr {
-                    return smallvec![attr.clone()];
-                }
-
-                let subtree = match attr.token_tree_value() {
-                    Some(it) => it,
-                    _ => return smallvec![attr.clone()],
-                };
-
-                // Input subtree is: `(cfg, $(attr),+)`
-                // Split it up into a `cfg` subtree and the `attr` subtrees.
-                // FIXME: There should be a common API for this.
-                let mut parts = subtree.token_trees.split(|tt| {
-                    matches!(tt, tt::TokenTree::Leaf(tt::Leaf::Punct(Punct { char: ',', .. })))
-                });
-                let cfg = match parts.next() {
-                    Some(it) => it,
-                    None => return smallvec![],
-                };
-                let cfg = Subtree { delimiter: subtree.delimiter, token_trees: cfg.to_vec() };
-                let cfg = CfgExpr::parse(&cfg);
-                let index = attr.id;
-                let attrs = parts.filter(|a| !a.is_empty()).filter_map(|attr| {
-                    let tree = Subtree { delimiter: None, token_trees: attr.to_vec() };
-                    // FIXME hygiene
-                    let hygiene = Hygiene::new_unhygienic();
-                    Attr::from_tt(db, &tree, &hygiene, index)
-                });
-
-                let cfg_options = &crate_graph[krate].cfg_options;
-                if cfg_options.check(&cfg) == Some(false) {
-                    smallvec![]
-                } else {
-                    cov_mark::hit!(cfg_attr_active);
-
-                    attrs.collect()
-                }
-            })
-            .collect();
-
-        Attrs(RawAttrs { entries: Some(new_attrs) })
-    }
-}
-
 impl Attrs {
     pub const EMPTY: Self = Self(RawAttrs::EMPTY);
 
@@ -251,19 +127,18 @@ impl Attrs {
                 let enum_ = &item_tree[loc.id.value];
 
                 let cfg_options = &crate_graph[krate].cfg_options;
-                let variant = 'tri: loop {
-                    let mut idx = 0;
-                    for variant in enum_.variants.clone() {
-                        let attrs = item_tree.attrs(db, krate, variant.into());
-                        if attrs.is_cfg_enabled(cfg_options) {
-                            if it.local_id == Idx::from_raw(RawIdx::from(idx)) {
-                                break 'tri variant;
-                            }
-                            idx += 1;
-                        }
-                    }
+
+                let Some(variant) = enum_.variants.clone().filter(|variant| {
+                    let attrs = item_tree.attrs(db, krate, (*variant).into());
+                    attrs.is_cfg_enabled(cfg_options)
+                })
+                .zip(0u32..)
+                .find(|(_variant, idx)| it.local_id == Idx::from_raw(RawIdx::from(*idx)))
+                .map(|(variant, _idx)| variant)
+                else {
                     return Arc::new(res);
                 };
+
                 (item_tree[variant].fields.clone(), item_tree, krate)
             }
             VariantId::StructId(it) => {
@@ -358,7 +233,7 @@ impl Attrs {
 
     pub fn has_doc_hidden(&self) -> bool {
         self.by_key("doc").tt_values().any(|tt| {
-            tt.delimiter_kind() == Some(DelimiterKind::Parenthesis) &&
+            tt.delimiter.kind == DelimiterKind::Parenthesis &&
                 matches!(&*tt.token_trees, [tt::TokenTree::Leaf(tt::Leaf::Ident(ident))] if ident.text == "hidden")
         })
     }
@@ -403,7 +278,7 @@ impl AttrsWithOwner {
                         .raw_attrs(AttrOwner::ModItem(definition_tree_id.value.into()))
                         .clone(),
                     ModuleOrigin::BlockExpr { block } => RawAttrs::from_attrs_owner(
-                        db,
+                        db.upcast(),
                         InFile::new(block.file_id, block.to_node(db.upcast()))
                             .as_ref()
                             .map(|it| it as &dyn ast::HasAttrs),
@@ -439,7 +314,7 @@ impl AttrsWithOwner {
                 GenericParamId::ConstParamId(it) => {
                     let src = it.parent().child_source(db);
                     RawAttrs::from_attrs_owner(
-                        db,
+                        db.upcast(),
                         src.with_value(src.value[it.local_id()].as_ref().either(
                             |it| match it {
                                 ast::TypeOrConstParam::Type(it) => it as _,
@@ -452,7 +327,7 @@ impl AttrsWithOwner {
                 GenericParamId::TypeParamId(it) => {
                     let src = it.parent().child_source(db);
                     RawAttrs::from_attrs_owner(
-                        db,
+                        db.upcast(),
                         src.with_value(src.value[it.local_id()].as_ref().either(
                             |it| match it {
                                 ast::TypeOrConstParam::Type(it) => it as _,
@@ -464,14 +339,14 @@ impl AttrsWithOwner {
                 }
                 GenericParamId::LifetimeParamId(it) => {
                     let src = it.parent.child_source(db);
-                    RawAttrs::from_attrs_owner(db, src.with_value(&src.value[it.local_id]))
+                    RawAttrs::from_attrs_owner(db.upcast(), src.with_value(&src.value[it.local_id]))
                 }
             },
             AttrDefId::ExternBlockId(it) => attrs_from_item_tree(it.lookup(db).id, db),
         };
 
-        let attrs = raw_attrs.filter(db, def.krate(db));
-        Self { attrs, owner: def }
+        let attrs = raw_attrs.filter(db.upcast(), def.krate(db));
+        Self { attrs: Attrs(attrs), owner: def }
     }
 
     pub fn source_map(&self, db: &dyn DefDatabase) -> AttrSourceMap {
@@ -627,40 +502,6 @@ fn doc_indent(attrs: &Attrs) -> usize {
         .unwrap_or(0)
 }
 
-fn inner_attributes(
-    syntax: &SyntaxNode,
-) -> Option<impl Iterator<Item = Either<ast::Attr, ast::Comment>>> {
-    let node = match_ast! {
-        match syntax {
-            ast::SourceFile(_) => syntax.clone(),
-            ast::ExternBlock(it) => it.extern_item_list()?.syntax().clone(),
-            ast::Fn(it) => it.body()?.stmt_list()?.syntax().clone(),
-            ast::Impl(it) => it.assoc_item_list()?.syntax().clone(),
-            ast::Module(it) => it.item_list()?.syntax().clone(),
-            ast::BlockExpr(it) => {
-                use syntax::SyntaxKind::{BLOCK_EXPR , EXPR_STMT};
-                // Block expressions accept outer and inner attributes, but only when they are the outer
-                // expression of an expression statement or the final expression of another block expression.
-                let may_carry_attributes = matches!(
-                    it.syntax().parent().map(|it| it.kind()),
-                     Some(BLOCK_EXPR | EXPR_STMT)
-                );
-                if !may_carry_attributes {
-                    return None
-                }
-                syntax.clone()
-            },
-            _ => return None,
-        }
-    };
-
-    let attrs = ast::AttrDocCommentIter::from_syntax_node(&node).filter(|el| match el {
-        Either::Left(attr) => attr.kind().is_inner(),
-        Either::Right(comment) => comment.is_inner(),
-    });
-    Some(attrs)
-}
-
 #[derive(Debug)]
 pub struct AttrSourceMap {
     source: Vec<Either<ast::Attr, ast::Comment>>,
@@ -703,7 +544,7 @@ impl AttrSourceMap {
     }
 
     fn source_of_id(&self, id: AttrId) -> InFile<&Either<ast::Attr, ast::Comment>> {
-        let ast_idx = id.ast_index as usize;
+        let ast_idx = id.ast_index();
         let file_id = match self.mod_def_site_file_id {
             Some((file_id, def_site_cut)) if def_site_cut <= ast_idx => file_id,
             _ => self.file_id,
@@ -779,128 +620,6 @@ fn get_doc_string_in_attr(it: &ast::Attr) -> Option<ast::String> {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct AttrId {
-    pub(crate) ast_index: u32,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq)]
-pub struct Attr {
-    pub(crate) id: AttrId,
-    pub(crate) path: Interned<ModPath>,
-    pub(crate) input: Option<Interned<AttrInput>>,
-}
-
-#[derive(Debug, Clone, PartialEq, Eq, Hash)]
-pub enum AttrInput {
-    /// `#[attr = "string"]`
-    Literal(SmolStr),
-    /// `#[attr(subtree)]`
-    TokenTree(tt::Subtree, mbe::TokenMap),
-}
-
-impl fmt::Display for AttrInput {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            AttrInput::Literal(lit) => write!(f, " = \"{}\"", lit.escape_debug()),
-            AttrInput::TokenTree(subtree, _) => subtree.fmt(f),
-        }
-    }
-}
-
-impl Attr {
-    fn from_src(
-        db: &dyn DefDatabase,
-        ast: ast::Meta,
-        hygiene: &Hygiene,
-        id: AttrId,
-    ) -> Option<Attr> {
-        let path = Interned::new(ModPath::from_src(db.upcast(), ast.path()?, hygiene)?);
-        let input = if let Some(ast::Expr::Literal(lit)) = ast.expr() {
-            let value = match lit.kind() {
-                ast::LiteralKind::String(string) => string.value()?.into(),
-                _ => lit.syntax().first_token()?.text().trim_matches('"').into(),
-            };
-            Some(Interned::new(AttrInput::Literal(value)))
-        } else if let Some(tt) = ast.token_tree() {
-            let (tree, map) = syntax_node_to_token_tree(tt.syntax());
-            Some(Interned::new(AttrInput::TokenTree(tree, map)))
-        } else {
-            None
-        };
-        Some(Attr { id, path, input })
-    }
-
-    fn from_tt(
-        db: &dyn DefDatabase,
-        tt: &tt::Subtree,
-        hygiene: &Hygiene,
-        id: AttrId,
-    ) -> Option<Attr> {
-        let (parse, _) = mbe::token_tree_to_syntax_node(tt, mbe::TopEntryPoint::MetaItem);
-        let ast = ast::Meta::cast(parse.syntax_node())?;
-
-        Self::from_src(db, ast, hygiene, id)
-    }
-
-    pub fn path(&self) -> &ModPath {
-        &self.path
-    }
-}
-
-impl Attr {
-    /// #[path = "string"]
-    pub fn string_value(&self) -> Option<&SmolStr> {
-        match self.input.as_deref()? {
-            AttrInput::Literal(it) => Some(it),
-            _ => None,
-        }
-    }
-
-    /// #[path(ident)]
-    pub fn single_ident_value(&self) -> Option<&tt::Ident> {
-        match self.input.as_deref()? {
-            AttrInput::TokenTree(subtree, _) => match &*subtree.token_trees {
-                [tt::TokenTree::Leaf(tt::Leaf::Ident(ident))] => Some(ident),
-                _ => None,
-            },
-            _ => None,
-        }
-    }
-
-    /// #[path TokenTree]
-    pub fn token_tree_value(&self) -> Option<&Subtree> {
-        match self.input.as_deref()? {
-            AttrInput::TokenTree(subtree, _) => Some(subtree),
-            _ => None,
-        }
-    }
-
-    /// Parses this attribute as a token tree consisting of comma separated paths.
-    pub fn parse_path_comma_token_tree(&self) -> Option<impl Iterator<Item = ModPath> + '_> {
-        let args = self.token_tree_value()?;
-
-        if args.delimiter_kind() != Some(DelimiterKind::Parenthesis) {
-            return None;
-        }
-        let paths = args
-            .token_trees
-            .split(|tt| matches!(tt, tt::TokenTree::Leaf(tt::Leaf::Punct(Punct { char: ',', .. }))))
-            .filter_map(|tts| {
-                if tts.is_empty() {
-                    return None;
-                }
-                let segments = tts.iter().filter_map(|tt| match tt {
-                    tt::TokenTree::Leaf(tt::Leaf::Ident(id)) => Some(id.as_name()),
-                    _ => None,
-                });
-                Some(ModPath::from_segments(PathKind::Plain, segments))
-            });
-
-        Some(paths)
-    }
-}
-
 #[derive(Debug, Clone, Copy)]
 pub struct AttrQuery<'attr> {
     attrs: &'attr Attrs,
@@ -908,7 +627,7 @@ pub struct AttrQuery<'attr> {
 }
 
 impl<'attr> AttrQuery<'attr> {
-    pub fn tt_values(self) -> impl Iterator<Item = &'attr Subtree> {
+    pub fn tt_values(self) -> impl Iterator<Item = &'attr crate::tt::Subtree> {
         self.attrs().filter_map(|attr| attr.token_tree_value())
     }
 
@@ -953,21 +672,6 @@ fn attrs_from_item_tree<N: ItemTreeNode>(id: ItemTreeId<N>, db: &dyn DefDatabase
     tree.raw_attrs(mod_item.into()).clone()
 }
 
-fn collect_attrs(
-    owner: &dyn ast::HasAttrs,
-) -> impl Iterator<Item = (AttrId, Either<ast::Attr, ast::Comment>)> {
-    let inner_attrs = inner_attributes(owner.syntax()).into_iter().flatten();
-    let outer_attrs =
-        ast::AttrDocCommentIter::from_syntax_node(owner.syntax()).filter(|el| match el {
-            Either::Left(attr) => attr.kind().is_outer(),
-            Either::Right(comment) => comment.is_outer(),
-        });
-    outer_attrs
-        .chain(inner_attrs)
-        .enumerate()
-        .map(|(id, attr)| (AttrId { ast_index: id as u32 }, attr))
-}
-
 pub(crate) fn variants_attrs_source_map(
     db: &dyn DefDatabase,
     def: EnumId,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/body.rs b/src/tools/rust-analyzer/crates/hir-def/src/body.rs
index 78fbaa9d7..8fd9255b8 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/body.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/body.rs
@@ -12,15 +12,17 @@ use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use drop_bomb::DropBomb;
 use either::Either;
-use hir_expand::{hygiene::Hygiene, ExpandError, ExpandResult, HirFileId, InFile, MacroCallId};
+use hir_expand::{
+    attrs::RawAttrs, hygiene::Hygiene, ExpandError, ExpandResult, HirFileId, InFile, MacroCallId,
+};
 use la_arena::{Arena, ArenaMap};
 use limit::Limit;
 use profile::Count;
 use rustc_hash::FxHashMap;
-use syntax::{ast, AstPtr, SyntaxNodePtr};
+use syntax::{ast, AstPtr, SyntaxNode, SyntaxNodePtr};
 
 use crate::{
-    attr::{Attrs, RawAttrs},
+    attr::Attrs,
     db::DefDatabase,
     expr::{dummy_expr_id, Expr, ExprId, Label, LabelId, Pat, PatId},
     item_scope::BuiltinShadowMode,
@@ -49,7 +51,8 @@ pub struct Expander {
     def_map: Arc<DefMap>,
     current_file_id: HirFileId,
     module: LocalModuleId,
-    recursion_limit: usize,
+    /// `recursion_depth == usize::MAX` indicates that the recursion limit has been reached.
+    recursion_depth: usize,
 }
 
 impl CfgExpander {
@@ -64,7 +67,7 @@ impl CfgExpander {
     }
 
     pub(crate) fn parse_attrs(&self, db: &dyn DefDatabase, owner: &dyn ast::HasAttrs) -> Attrs {
-        RawAttrs::new(db, owner, &self.hygiene).filter(db, self.krate)
+        Attrs::filter(db, self.krate, RawAttrs::new(db.upcast(), owner, &self.hygiene))
     }
 
     pub(crate) fn is_cfg_enabled(&self, db: &dyn DefDatabase, owner: &dyn ast::HasAttrs) -> bool {
@@ -82,7 +85,7 @@ impl Expander {
             def_map,
             current_file_id,
             module: module.local_id,
-            recursion_limit: 0,
+            recursion_depth: 0,
         }
     }
 
@@ -91,31 +94,37 @@ impl Expander {
         db: &dyn DefDatabase,
         macro_call: ast::MacroCall,
     ) -> Result<ExpandResult<Option<(Mark, T)>>, UnresolvedMacro> {
-        if self.recursion_limit(db).check(self.recursion_limit + 1).is_err() {
-            cov_mark::hit!(your_stack_belongs_to_me);
-            return Ok(ExpandResult::only_err(ExpandError::Other(
-                "reached recursion limit during macro expansion".into(),
-            )));
+        let mut unresolved_macro_err = None;
+
+        let result = self.within_limit(db, |this| {
+            let macro_call = InFile::new(this.current_file_id, &macro_call);
+
+            let resolver =
+                |path| this.resolve_path_as_macro(db, &path).map(|it| macro_id_to_def_id(db, it));
+
+            let mut err = None;
+            let call_id = match macro_call.as_call_id_with_errors(
+                db,
+                this.def_map.krate(),
+                resolver,
+                &mut |e| {
+                    err.get_or_insert(e);
+                },
+            ) {
+                Ok(call_id) => call_id,
+                Err(resolve_err) => {
+                    unresolved_macro_err = Some(resolve_err);
+                    return ExpandResult { value: None, err: None };
+                }
+            };
+            ExpandResult { value: call_id.ok(), err }
+        });
+
+        if let Some(err) = unresolved_macro_err {
+            Err(err)
+        } else {
+            Ok(result)
         }
-
-        let macro_call = InFile::new(self.current_file_id, &macro_call);
-
-        let resolver =
-            |path| self.resolve_path_as_macro(db, &path).map(|it| macro_id_to_def_id(db, it));
-
-        let mut err = None;
-        let call_id =
-            macro_call.as_call_id_with_errors(db, self.def_map.krate(), resolver, &mut |e| {
-                err.get_or_insert(e);
-            })?;
-        let call_id = match call_id {
-            Ok(it) => it,
-            Err(_) => {
-                return Ok(ExpandResult { value: None, err });
-            }
-        };
-
-        Ok(self.enter_expand_inner(db, call_id, err))
     }
 
     pub fn enter_expand_id<T: ast::AstNode>(
@@ -123,15 +132,14 @@ impl Expander {
         db: &dyn DefDatabase,
         call_id: MacroCallId,
     ) -> ExpandResult<Option<(Mark, T)>> {
-        self.enter_expand_inner(db, call_id, None)
+        self.within_limit(db, |_this| ExpandResult::ok(Some(call_id)))
     }
 
-    fn enter_expand_inner<T: ast::AstNode>(
-        &mut self,
+    fn enter_expand_inner(
         db: &dyn DefDatabase,
         call_id: MacroCallId,
         mut err: Option<ExpandError>,
-    ) -> ExpandResult<Option<(Mark, T)>> {
+    ) -> ExpandResult<Option<(HirFileId, SyntaxNode)>> {
         if err.is_none() {
             err = db.macro_expand_error(call_id);
         }
@@ -152,29 +160,21 @@ impl Expander {
             }
         };
 
-        let node = match T::cast(raw_node) {
-            Some(it) => it,
-            None => {
-                // This can happen without being an error, so only forward previous errors.
-                return ExpandResult { value: None, err };
-            }
-        };
-
-        tracing::debug!("macro expansion {:#?}", node.syntax());
-
-        self.recursion_limit += 1;
-        let mark =
-            Mark { file_id: self.current_file_id, bomb: DropBomb::new("expansion mark dropped") };
-        self.cfg_expander.hygiene = Hygiene::new(db.upcast(), file_id);
-        self.current_file_id = file_id;
-
-        ExpandResult { value: Some((mark, node)), err }
+        ExpandResult { value: Some((file_id, raw_node)), err }
     }
 
     pub fn exit(&mut self, db: &dyn DefDatabase, mut mark: Mark) {
         self.cfg_expander.hygiene = Hygiene::new(db.upcast(), mark.file_id);
         self.current_file_id = mark.file_id;
-        self.recursion_limit -= 1;
+        if self.recursion_depth == usize::MAX {
+            // Recursion limit has been reached somewhere in the macro expansion tree. Reset the
+            // depth only when we get out of the tree.
+            if !self.current_file_id.is_macro() {
+                self.recursion_depth = 0;
+            }
+        } else {
+            self.recursion_depth -= 1;
+        }
         mark.bomb.defuse();
     }
 
@@ -213,6 +213,50 @@ impl Expander {
         #[cfg(test)]
         return Limit::new(std::cmp::min(32, limit));
     }
+
+    fn within_limit<F, T: ast::AstNode>(
+        &mut self,
+        db: &dyn DefDatabase,
+        op: F,
+    ) -> ExpandResult<Option<(Mark, T)>>
+    where
+        F: FnOnce(&mut Self) -> ExpandResult<Option<MacroCallId>>,
+    {
+        if self.recursion_depth == usize::MAX {
+            // Recursion limit has been reached somewhere in the macro expansion tree. We should
+            // stop expanding other macro calls in this tree, or else this may result in
+            // exponential number of macro expansions, leading to a hang.
+            //
+            // The overflow error should have been reported when it occurred (see the next branch),
+            // so don't return overflow error here to avoid diagnostics duplication.
+            cov_mark::hit!(overflow_but_not_me);
+            return ExpandResult::only_err(ExpandError::RecursionOverflowPosioned);
+        } else if self.recursion_limit(db).check(self.recursion_depth + 1).is_err() {
+            self.recursion_depth = usize::MAX;
+            cov_mark::hit!(your_stack_belongs_to_me);
+            return ExpandResult::only_err(ExpandError::Other(
+                "reached recursion limit during macro expansion".into(),
+            ));
+        }
+
+        let ExpandResult { value, err } = op(self);
+        let Some(call_id) = value else {
+            return ExpandResult { value: None, err };
+        };
+
+        Self::enter_expand_inner(db, call_id, err).map(|value| {
+            value.and_then(|(new_file_id, node)| {
+                let node = T::cast(node)?;
+
+                self.recursion_depth += 1;
+                self.cfg_expander.hygiene = Hygiene::new(db.upcast(), new_file_id);
+                let old_file_id = std::mem::replace(&mut self.current_file_id, new_file_id);
+                let mark =
+                    Mark { file_id: old_file_id, bomb: DropBomb::new("expansion mark dropped") };
+                Some((mark, node))
+            })
+        })
+    }
 }
 
 #[derive(Debug)]
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/body/lower.rs b/src/tools/rust-analyzer/crates/hir-def/src/body/lower.rs
index e8da24e3a..04b1c4f01 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/body/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/body/lower.rs
@@ -10,6 +10,7 @@ use hir_expand::{
     name::{name, AsName, Name},
     AstId, ExpandError, HirFileId, InFile,
 };
+use intern::Interned;
 use la_arena::Arena;
 use once_cell::unsync::OnceCell;
 use profile::Count;
@@ -33,7 +34,6 @@ use crate::{
         Label, LabelId, Literal, MatchArm, Movability, Pat, PatId, RecordFieldPat, RecordLitField,
         Statement,
     },
-    intern::Interned,
     item_scope::BuiltinShadowMode,
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
@@ -67,9 +67,9 @@ impl<'a> LowerCtx<'a> {
         Path::from_src(ast, self)
     }
 
-    pub(crate) fn ast_id<N: AstNode>(&self, db: &dyn DefDatabase, item: &N) -> Option<AstId<N>> {
+    pub(crate) fn ast_id<N: AstNode>(&self, item: &N) -> Option<AstId<N>> {
         let &(file_id, ref ast_id_map) = self.ast_id_map.as_ref()?;
-        let ast_id_map = ast_id_map.get_or_init(|| db.ast_id_map(file_id));
+        let ast_id_map = ast_id_map.get_or_init(|| self.db.ast_id_map(file_id));
         Some(InFile::new(file_id, ast_id_map.ast_id(item)))
     }
 }
@@ -624,6 +624,10 @@ impl ExprCollector<'_> {
                         krate: *krate,
                     });
                 }
+                Some(ExpandError::RecursionOverflowPosioned) => {
+                    // Recursion limit has been reached in the macro expansion tree, but not in
+                    // this very macro call. Don't add diagnostics to avoid duplication.
+                }
                 Some(err) => {
                     self.source_map.diagnostics.push(BodyDiagnostic::MacroError {
                         node: InFile::new(outer_file, syntax_ptr),
@@ -636,6 +640,8 @@ impl ExprCollector<'_> {
 
         match res.value {
             Some((mark, expansion)) => {
+                // Keep collecting even with expansion errors so we can provide completions and
+                // other services in incomplete macro expressions.
                 self.source_map.expansions.insert(macro_call_ptr, self.expander.current_file_id);
                 let prev_ast_id_map = mem::replace(
                     &mut self.ast_id_map,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/body/pretty.rs b/src/tools/rust-analyzer/crates/hir-def/src/body/pretty.rs
index 10b9b26bb..4b4664a1c 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/body/pretty.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/body/pretty.rs
@@ -80,7 +80,7 @@ impl<'a> Write for Printer<'a> {
     fn write_str(&mut self, s: &str) -> fmt::Result {
         for line in s.split_inclusive('\n') {
             if self.needs_indent {
-                match self.buf.chars().rev().skip_while(|ch| *ch == ' ').next() {
+                match self.buf.chars().rev().find(|ch| *ch != ' ') {
                     Some('\n') | None => {}
                     _ => self.buf.push('\n'),
                 }
@@ -113,7 +113,7 @@ impl<'a> Printer<'a> {
     }
 
     fn newline(&mut self) {
-        match self.buf.chars().rev().skip_while(|ch| *ch == ' ').next() {
+        match self.buf.chars().rev().find(|ch| *ch != ' ') {
             Some('\n') | None => {}
             _ => writeln!(self).unwrap(),
         }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/body/tests.rs b/src/tools/rust-analyzer/crates/hir-def/src/body/tests.rs
index c9601f855..edee2c7ff 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/body/tests.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/body/tests.rs
@@ -62,6 +62,19 @@ fn main() { n_nuple!(1,2,3); }
 }
 
 #[test]
+fn your_stack_belongs_to_me2() {
+    cov_mark::check!(overflow_but_not_me);
+    lower(
+        r#"
+macro_rules! foo {
+    () => {{ foo!(); foo!(); }}
+}
+fn main() { foo!(); }
+"#,
+    );
+}
+
+#[test]
 fn recursion_limit() {
     cov_mark::check!(your_stack_belongs_to_me);
 
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/child_by_source.rs b/src/tools/rust-analyzer/crates/hir-def/src/child_by_source.rs
index bb1316525..19d2fe956 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/child_by_source.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/child_by_source.rs
@@ -117,7 +117,7 @@ impl ChildBySource for ItemScope {
                 let adt = ast_id.to_node(db.upcast());
                 calls.for_each(|(attr_id, call_id, calls)| {
                     if let Some(Either::Left(attr)) =
-                        adt.doc_comments_and_attrs().nth(attr_id.ast_index as usize)
+                        adt.doc_comments_and_attrs().nth(attr_id.ast_index())
                     {
                         res[keys::DERIVE_MACRO_CALL].insert(attr, (attr_id, call_id, calls.into()));
                     }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/data.rs b/src/tools/rust-analyzer/crates/hir-def/src/data.rs
index e6b05f27a..c3c1dfd39 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/data.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/data.rs
@@ -3,6 +3,7 @@
 use std::sync::Arc;
 
 use hir_expand::{name::Name, AstId, ExpandResult, HirFileId, InFile, MacroCallId, MacroDefKind};
+use intern::Interned;
 use smallvec::SmallVec;
 use syntax::ast;
 
@@ -10,7 +11,6 @@ use crate::{
     attr::Attrs,
     body::{Expander, Mark},
     db::DefDatabase,
-    intern::Interned,
     item_tree::{self, AssocItem, FnFlags, ItemTree, ItemTreeId, ModItem, Param, TreeId},
     nameres::{
         attr_resolution::ResolvedAttr,
@@ -142,7 +142,7 @@ impl FunctionData {
     }
 }
 
-fn parse_rustc_legacy_const_generics(tt: &tt::Subtree) -> Box<[u32]> {
+fn parse_rustc_legacy_const_generics(tt: &crate::tt::Subtree) -> Box<[u32]> {
     let mut indices = Vec::new();
     for args in tt.token_trees.chunks(2) {
         match &args[0] {
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/db.rs b/src/tools/rust-analyzer/crates/hir-def/src/db.rs
index 431c82554..b23427a73 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/db.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/db.rs
@@ -4,8 +4,9 @@ use std::sync::Arc;
 use base_db::{salsa, CrateId, SourceDatabase, Upcast};
 use either::Either;
 use hir_expand::{db::AstDatabase, HirFileId};
+use intern::Interned;
 use la_arena::ArenaMap;
-use syntax::{ast, AstPtr, SmolStr};
+use syntax::{ast, AstPtr};
 
 use crate::{
     adt::{EnumData, StructData},
@@ -17,9 +18,8 @@ use crate::{
     },
     generics::GenericParams,
     import_map::ImportMap,
-    intern::Interned,
     item_tree::{AttrOwner, ItemTree},
-    lang_item::{LangItemTarget, LangItems},
+    lang_item::{LangItem, LangItemTarget, LangItems},
     nameres::{diagnostics::DefDiagnostic, DefMap},
     visibility::{self, Visibility},
     AttrDefId, BlockId, BlockLoc, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, ExternBlockId,
@@ -183,7 +183,7 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     fn crate_lang_items(&self, krate: CrateId) -> Arc<LangItems>;
 
     #[salsa::invoke(LangItems::lang_item_query)]
-    fn lang_item(&self, start_crate: CrateId, item: SmolStr) -> Option<LangItemTarget>;
+    fn lang_item(&self, start_crate: CrateId, item: LangItem) -> Option<LangItemTarget>;
 
     #[salsa::invoke(ImportMap::import_map_query)]
     fn import_map(&self, krate: CrateId) -> Arc<ImportMap>;
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/expr.rs b/src/tools/rust-analyzer/crates/hir-def/src/expr.rs
index 7b6569421..48028b7c6 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/expr.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/expr.rs
@@ -15,11 +15,11 @@
 use std::fmt;
 
 use hir_expand::name::Name;
+use intern::Interned;
 use la_arena::{Idx, RawIdx};
 
 use crate::{
     builtin_type::{BuiltinFloat, BuiltinInt, BuiltinUint},
-    intern::Interned,
     path::{GenericArgs, Path},
     type_ref::{Mutability, Rawness, TypeRef},
     BlockId,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/find_path.rs b/src/tools/rust-analyzer/crates/hir-def/src/find_path.rs
index ddd7ad99e..3f4392320 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/find_path.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/find_path.rs
@@ -811,7 +811,7 @@ pub struct S;
     fn prelude() {
         check_found_path(
             r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 $0
 //- /std.rs crate:std
 pub mod prelude {
@@ -852,7 +852,7 @@ pub mod prelude {
     fn imported_prelude() {
         check_found_path(
             r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 use S;
 $0
 //- /std.rs crate:std
@@ -872,7 +872,7 @@ pub mod prelude {
     #[test]
     fn enum_variant_from_prelude() {
         let code = r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 $0
 //- /std.rs crate:std
 pub mod prelude {
@@ -1273,7 +1273,7 @@ fn f() {
     fn prelude_with_inner_items() {
         check_found_path(
             r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 fn f() {
     fn inner() {}
     $0
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/generics.rs b/src/tools/rust-analyzer/crates/hir-def/src/generics.rs
index f74559f5d..b2ab0c30e 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/generics.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/generics.rs
@@ -9,6 +9,7 @@ use hir_expand::{
     name::{AsName, Name},
     ExpandResult, HirFileId, InFile,
 };
+use intern::Interned;
 use la_arena::{Arena, ArenaMap, Idx};
 use once_cell::unsync::Lazy;
 use std::ops::DerefMut;
@@ -20,7 +21,6 @@ use crate::{
     child_by_source::ChildBySource,
     db::DefDatabase,
     dyn_map::DynMap,
-    intern::Interned,
     keys,
     src::{HasChildSource, HasSource},
     type_ref::{LifetimeRef, TypeBound, TypeRef},
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/intern.rs b/src/tools/rust-analyzer/crates/hir-def/src/intern.rs
deleted file mode 100644
index f08521a34..000000000
--- a/src/tools/rust-analyzer/crates/hir-def/src/intern.rs
+++ /dev/null
@@ -1,227 +0,0 @@
-//! Global `Arc`-based object interning infrastructure.
-//!
-//! Eventually this should probably be replaced with salsa-based interning.
-
-use std::{
-    fmt::{self, Debug, Display},
-    hash::{BuildHasherDefault, Hash, Hasher},
-    ops::Deref,
-    sync::Arc,
-};
-
-use dashmap::{DashMap, SharedValue};
-use hashbrown::HashMap;
-use once_cell::sync::OnceCell;
-use rustc_hash::FxHasher;
-
-use crate::generics::GenericParams;
-
-type InternMap<T> = DashMap<Arc<T>, (), BuildHasherDefault<FxHasher>>;
-type Guard<T> = dashmap::RwLockWriteGuard<
-    'static,
-    HashMap<Arc<T>, SharedValue<()>, BuildHasherDefault<FxHasher>>,
->;
-
-pub struct Interned<T: Internable + ?Sized> {
-    arc: Arc<T>,
-}
-
-impl<T: Internable> Interned<T> {
-    pub fn new(obj: T) -> Self {
-        match Interned::lookup(&obj) {
-            Ok(this) => this,
-            Err(shard) => {
-                let arc = Arc::new(obj);
-                Self::alloc(arc, shard)
-            }
-        }
-    }
-}
-
-impl<T: Internable + ?Sized> Interned<T> {
-    fn lookup(obj: &T) -> Result<Self, Guard<T>> {
-        let storage = T::storage().get();
-        let shard_idx = storage.determine_map(obj);
-        let shard = &storage.shards()[shard_idx];
-        let shard = shard.write();
-
-        // Atomically,
-        // - check if `obj` is already in the map
-        //   - if so, clone its `Arc` and return it
-        //   - if not, box it up, insert it, and return a clone
-        // This needs to be atomic (locking the shard) to avoid races with other thread, which could
-        // insert the same object between us looking it up and inserting it.
-
-        // FIXME: avoid double lookup/hashing by using raw entry API (once stable, or when
-        // hashbrown can be plugged into dashmap)
-        match shard.get_key_value(obj) {
-            Some((arc, _)) => Ok(Self { arc: arc.clone() }),
-            None => Err(shard),
-        }
-    }
-
-    fn alloc(arc: Arc<T>, mut shard: Guard<T>) -> Self {
-        let arc2 = arc.clone();
-
-        shard.insert(arc2, SharedValue::new(()));
-
-        Self { arc }
-    }
-}
-
-impl Interned<str> {
-    pub fn new_str(s: &str) -> Self {
-        match Interned::lookup(s) {
-            Ok(this) => this,
-            Err(shard) => {
-                let arc = Arc::<str>::from(s);
-                Self::alloc(arc, shard)
-            }
-        }
-    }
-}
-
-impl<T: Internable + ?Sized> Drop for Interned<T> {
-    #[inline]
-    fn drop(&mut self) {
-        // When the last `Ref` is dropped, remove the object from the global map.
-        if Arc::strong_count(&self.arc) == 2 {
-            // Only `self` and the global map point to the object.
-
-            self.drop_slow();
-        }
-    }
-}
-
-impl<T: Internable + ?Sized> Interned<T> {
-    #[cold]
-    fn drop_slow(&mut self) {
-        let storage = T::storage().get();
-        let shard_idx = storage.determine_map(&self.arc);
-        let shard = &storage.shards()[shard_idx];
-        let mut shard = shard.write();
-
-        // FIXME: avoid double lookup
-        let (arc, _) = shard.get_key_value(&self.arc).expect("interned value removed prematurely");
-
-        if Arc::strong_count(arc) != 2 {
-            // Another thread has interned another copy
-            return;
-        }
-
-        shard.remove(&self.arc);
-
-        // Shrink the backing storage if the shard is less than 50% occupied.
-        if shard.len() * 2 < shard.capacity() {
-            shard.shrink_to_fit();
-        }
-    }
-}
-
-/// Compares interned `Ref`s using pointer equality.
-impl<T: Internable> PartialEq for Interned<T> {
-    // NOTE: No `?Sized` because `ptr_eq` doesn't work right with trait objects.
-
-    #[inline]
-    fn eq(&self, other: &Self) -> bool {
-        Arc::ptr_eq(&self.arc, &other.arc)
-    }
-}
-
-impl<T: Internable> Eq for Interned<T> {}
-
-impl PartialEq for Interned<str> {
-    fn eq(&self, other: &Self) -> bool {
-        Arc::ptr_eq(&self.arc, &other.arc)
-    }
-}
-
-impl Eq for Interned<str> {}
-
-impl<T: Internable + ?Sized> Hash for Interned<T> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        // NOTE: Cast disposes vtable pointer / slice/str length.
-        state.write_usize(Arc::as_ptr(&self.arc) as *const () as usize)
-    }
-}
-
-impl<T: Internable + ?Sized> AsRef<T> for Interned<T> {
-    #[inline]
-    fn as_ref(&self) -> &T {
-        &self.arc
-    }
-}
-
-impl<T: Internable + ?Sized> Deref for Interned<T> {
-    type Target = T;
-
-    #[inline]
-    fn deref(&self) -> &Self::Target {
-        &self.arc
-    }
-}
-
-impl<T: Internable + ?Sized> Clone for Interned<T> {
-    fn clone(&self) -> Self {
-        Self { arc: self.arc.clone() }
-    }
-}
-
-impl<T: Debug + Internable + ?Sized> Debug for Interned<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (*self.arc).fmt(f)
-    }
-}
-
-impl<T: Display + Internable + ?Sized> Display for Interned<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        (*self.arc).fmt(f)
-    }
-}
-
-pub struct InternStorage<T: ?Sized> {
-    map: OnceCell<InternMap<T>>,
-}
-
-impl<T: ?Sized> InternStorage<T> {
-    pub const fn new() -> Self {
-        Self { map: OnceCell::new() }
-    }
-}
-
-impl<T: Internable + ?Sized> InternStorage<T> {
-    fn get(&self) -> &InternMap<T> {
-        self.map.get_or_init(DashMap::default)
-    }
-}
-
-pub trait Internable: Hash + Eq + 'static {
-    fn storage() -> &'static InternStorage<Self>;
-}
-
-/// Implements `Internable` for a given list of types, making them usable with `Interned`.
-#[macro_export]
-#[doc(hidden)]
-macro_rules! _impl_internable {
-    ( $($t:path),+ $(,)? ) => { $(
-        impl Internable for $t {
-            fn storage() -> &'static InternStorage<Self> {
-                static STORAGE: InternStorage<$t> = InternStorage::new();
-                &STORAGE
-            }
-        }
-    )+ };
-}
-
-pub use crate::_impl_internable as impl_internable;
-
-impl_internable!(
-    crate::type_ref::TypeRef,
-    crate::type_ref::TraitRef,
-    crate::type_ref::TypeBound,
-    crate::path::ModPath,
-    crate::path::GenericArgs,
-    crate::attr::AttrInput,
-    GenericParams,
-    str,
-);
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/item_scope.rs b/src/tools/rust-analyzer/crates/hir-def/src/item_scope.rs
index c7b213b7e..53a4173ff 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/item_scope.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/item_scope.rs
@@ -4,7 +4,7 @@
 use std::collections::hash_map::Entry;
 
 use base_db::CrateId;
-use hir_expand::{name::Name, AstId, MacroCallId};
+use hir_expand::{attrs::AttrId, name::Name, AstId, MacroCallId};
 use itertools::Itertools;
 use once_cell::sync::Lazy;
 use profile::Count;
@@ -14,8 +14,8 @@ use stdx::format_to;
 use syntax::ast;
 
 use crate::{
-    attr::AttrId, db::DefDatabase, per_ns::PerNs, visibility::Visibility, AdtId, BuiltinType,
-    ConstId, HasModule, ImplId, LocalModuleId, MacroId, ModuleDefId, ModuleId, TraitId,
+    db::DefDatabase, per_ns::PerNs, visibility::Visibility, AdtId, BuiltinType, ConstId, HasModule,
+    ImplId, LocalModuleId, MacroId, ModuleDefId, ModuleId, TraitId,
 };
 
 #[derive(Copy, Clone, Debug)]
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/item_tree.rs b/src/tools/rust-analyzer/crates/hir-def/src/item_tree.rs
index 80297f8ad..19d01630e 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/item_tree.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/item_tree.rs
@@ -48,10 +48,12 @@ use base_db::CrateId;
 use either::Either;
 use hir_expand::{
     ast_id_map::FileAstId,
+    attrs::RawAttrs,
     hygiene::Hygiene,
     name::{name, AsName, Name},
     ExpandTo, HirFileId, InFile,
 };
+use intern::Interned;
 use la_arena::{Arena, Idx, IdxRange, RawIdx};
 use profile::Count;
 use rustc_hash::FxHashMap;
@@ -60,10 +62,9 @@ use stdx::never;
 use syntax::{ast, match_ast, SyntaxKind};
 
 use crate::{
-    attr::{Attrs, RawAttrs},
+    attr::Attrs,
     db::DefDatabase,
     generics::GenericParams,
-    intern::Interned,
     path::{path, AssociatedTypeBinding, GenericArgs, ImportAlias, ModPath, Path, PathKind},
     type_ref::{Mutability, TraitRef, TypeBound, TypeRef},
     visibility::RawVisibility,
@@ -110,7 +111,8 @@ impl ItemTree {
             Some(node) => node,
             None => return Default::default(),
         };
-        if never!(syntax.kind() == SyntaxKind::ERROR) {
+        if never!(syntax.kind() == SyntaxKind::ERROR, "{:?} from {:?} {}", file_id, syntax, syntax)
+        {
             // FIXME: not 100% sure why these crop up, but return an empty tree to avoid a panic
             return Default::default();
         }
@@ -120,7 +122,7 @@ impl ItemTree {
         let mut item_tree = match_ast! {
             match syntax {
                 ast::SourceFile(file) => {
-                    top_attrs = Some(RawAttrs::new(db, &file, ctx.hygiene()));
+                    top_attrs = Some(RawAttrs::new(db.upcast(), &file, ctx.hygiene()));
                     ctx.lower_module_items(&file)
                 },
                 ast::MacroItems(items) => {
@@ -132,7 +134,7 @@ impl ItemTree {
                     ctx.lower_macro_stmts(stmts)
                 },
                 _ => {
-                    panic!("cannot create item tree from {syntax:?} {syntax}");
+                    panic!("cannot create item tree for file {file_id:?} from {syntax:?} {syntax}");
                 },
             }
         };
@@ -152,7 +154,11 @@ impl ItemTree {
 
     /// Returns the inner attributes of the source file.
     pub fn top_level_attrs(&self, db: &dyn DefDatabase, krate: CrateId) -> Attrs {
-        self.attrs.get(&AttrOwner::TopLevel).unwrap_or(&RawAttrs::EMPTY).clone().filter(db, krate)
+        Attrs::filter(
+            db,
+            krate,
+            self.attrs.get(&AttrOwner::TopLevel).unwrap_or(&RawAttrs::EMPTY).clone(),
+        )
     }
 
     pub(crate) fn raw_attrs(&self, of: AttrOwner) -> &RawAttrs {
@@ -160,7 +166,7 @@ impl ItemTree {
     }
 
     pub(crate) fn attrs(&self, db: &dyn DefDatabase, krate: CrateId, of: AttrOwner) -> Attrs {
-        self.raw_attrs(of).clone().filter(db, krate)
+        Attrs::filter(db, krate, self.raw_attrs(of).clone())
     }
 
     pub fn pretty_print(&self) -> String {
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/item_tree/lower.rs b/src/tools/rust-analyzer/crates/hir-def/src/item_tree/lower.rs
index b25274bcc..d4d3c5ef1 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/item_tree/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/item_tree/lower.rs
@@ -99,7 +99,7 @@ impl<'a> Ctx<'a> {
     }
 
     fn lower_mod_item(&mut self, item: &ast::Item) -> Option<ModItem> {
-        let attrs = RawAttrs::new(self.db, item, self.hygiene());
+        let attrs = RawAttrs::new(self.db.upcast(), item, self.hygiene());
         let item: ModItem = match item {
             ast::Item::Struct(ast) => self.lower_struct(ast)?.into(),
             ast::Item::Union(ast) => self.lower_union(ast)?.into(),
@@ -173,7 +173,7 @@ impl<'a> Ctx<'a> {
         for field in fields.fields() {
             if let Some(data) = self.lower_record_field(&field) {
                 let idx = self.data().fields.alloc(data);
-                self.add_attrs(idx.into(), RawAttrs::new(self.db, &field, self.hygiene()));
+                self.add_attrs(idx.into(), RawAttrs::new(self.db.upcast(), &field, self.hygiene()));
             }
         }
         let end = self.next_field_idx();
@@ -194,7 +194,7 @@ impl<'a> Ctx<'a> {
         for (i, field) in fields.fields().enumerate() {
             let data = self.lower_tuple_field(i, &field);
             let idx = self.data().fields.alloc(data);
-            self.add_attrs(idx.into(), RawAttrs::new(self.db, &field, self.hygiene()));
+            self.add_attrs(idx.into(), RawAttrs::new(self.db.upcast(), &field, self.hygiene()));
         }
         let end = self.next_field_idx();
         IdxRange::new(start..end)
@@ -239,7 +239,10 @@ impl<'a> Ctx<'a> {
         for variant in variants.variants() {
             if let Some(data) = self.lower_variant(&variant) {
                 let idx = self.data().variants.alloc(data);
-                self.add_attrs(idx.into(), RawAttrs::new(self.db, &variant, self.hygiene()));
+                self.add_attrs(
+                    idx.into(),
+                    RawAttrs::new(self.db.upcast(), &variant, self.hygiene()),
+                );
             }
         }
         let end = self.next_variant_idx();
@@ -283,7 +286,10 @@ impl<'a> Ctx<'a> {
                 };
                 let ty = Interned::new(self_type);
                 let idx = self.data().params.alloc(Param::Normal(None, ty));
-                self.add_attrs(idx.into(), RawAttrs::new(self.db, &self_param, self.hygiene()));
+                self.add_attrs(
+                    idx.into(),
+                    RawAttrs::new(self.db.upcast(), &self_param, self.hygiene()),
+                );
                 has_self_param = true;
             }
             for param in param_list.params() {
@@ -307,7 +313,7 @@ impl<'a> Ctx<'a> {
                         self.data().params.alloc(Param::Normal(name, ty))
                     }
                 };
-                self.add_attrs(idx.into(), RawAttrs::new(self.db, &param, self.hygiene()));
+                self.add_attrs(idx.into(), RawAttrs::new(self.db.upcast(), &param, self.hygiene()));
             }
         }
         let end_param = self.next_param_idx();
@@ -442,7 +448,7 @@ impl<'a> Ctx<'a> {
         let items = trait_def.assoc_item_list().map(|list| {
             list.assoc_items()
                 .filter_map(|item| {
-                    let attrs = RawAttrs::new(self.db, &item, self.hygiene());
+                    let attrs = RawAttrs::new(self.db.upcast(), &item, self.hygiene());
                     self.lower_assoc_item(&item).map(|item| {
                         self.add_attrs(ModItem::from(item).into(), attrs);
                         item
@@ -471,7 +477,7 @@ impl<'a> Ctx<'a> {
             .flat_map(|it| it.assoc_items())
             .filter_map(|item| {
                 let assoc = self.lower_assoc_item(&item)?;
-                let attrs = RawAttrs::new(self.db, &item, self.hygiene());
+                let attrs = RawAttrs::new(self.db.upcast(), &item, self.hygiene());
                 self.add_attrs(ModItem::from(assoc).into(), attrs);
                 Some(assoc)
             })
@@ -541,7 +547,7 @@ impl<'a> Ctx<'a> {
                     // (in other words, the knowledge that they're in an extern block must not be used).
                     // This is because an extern block can contain macros whose ItemTree's top-level items
                     // should be considered to be in an extern block too.
-                    let attrs = RawAttrs::new(self.db, &item, self.hygiene());
+                    let attrs = RawAttrs::new(self.db.upcast(), &item, self.hygiene());
                     let id: ModItem = match item {
                         ast::ExternItem::Fn(ast) => self.lower_function(&ast)?.into(),
                         ast::ExternItem::Static(ast) => self.lower_static(&ast)?.into(),
@@ -653,15 +659,16 @@ fn desugar_future_path(orig: TypeRef) -> Path {
     let path = path![core::future::Future];
     let mut generic_args: Vec<_> =
         std::iter::repeat(None).take(path.segments().len() - 1).collect();
-    let mut last = GenericArgs::empty();
     let binding = AssociatedTypeBinding {
         name: name![Output],
         args: None,
         type_ref: Some(orig),
-        bounds: Vec::new(),
+        bounds: Box::default(),
     };
-    last.bindings.push(binding);
-    generic_args.push(Some(Interned::new(last)));
+    generic_args.push(Some(Interned::new(GenericArgs {
+        bindings: Box::new([binding]),
+        ..GenericArgs::empty()
+    })));
 
     Path::from_known_path(path, generic_args)
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/item_tree/pretty.rs b/src/tools/rust-analyzer/crates/hir-def/src/item_tree/pretty.rs
index 48c40df22..8f230b87d 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/item_tree/pretty.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/item_tree/pretty.rs
@@ -3,7 +3,6 @@
 use std::fmt::{self, Write};
 
 use crate::{
-    attr::RawAttrs,
     generics::{TypeOrConstParamData, WherePredicate, WherePredicateTypeTarget},
     pretty::{print_path, print_type_bounds, print_type_ref},
     visibility::RawVisibility,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/keys.rs b/src/tools/rust-analyzer/crates/hir-def/src/keys.rs
index c5cb9a2af..72beec818 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/keys.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/keys.rs
@@ -2,12 +2,11 @@
 
 use std::marker::PhantomData;
 
-use hir_expand::MacroCallId;
+use hir_expand::{attrs::AttrId, MacroCallId};
 use rustc_hash::FxHashMap;
 use syntax::{ast, AstNode, AstPtr};
 
 use crate::{
-    attr::AttrId,
     dyn_map::{DynMap, Policy},
     ConstId, EnumId, EnumVariantId, FieldId, FunctionId, ImplId, LifetimeParamId, Macro2Id,
     MacroRulesId, ProcMacroId, StaticId, StructId, TraitId, TypeAliasId, TypeOrConstParamId,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/lang_item.rs b/src/tools/rust-analyzer/crates/hir-def/src/lang_item.rs
index 877850184..ab9bc615d 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/lang_item.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/lang_item.rs
@@ -8,19 +8,21 @@ use rustc_hash::FxHashMap;
 use syntax::SmolStr;
 
 use crate::{
-    db::DefDatabase, AdtId, AttrDefId, CrateId, EnumId, EnumVariantId, FunctionId, ImplId,
-    ModuleDefId, StaticId, StructId, TraitId,
+    db::DefDatabase, AdtId, AssocItemId, AttrDefId, CrateId, EnumId, EnumVariantId, FunctionId,
+    ImplId, ModuleDefId, StaticId, StructId, TraitId, TypeAliasId, UnionId,
 };
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum LangItemTarget {
     EnumId(EnumId),
-    FunctionId(FunctionId),
-    ImplDefId(ImplId),
-    StaticId(StaticId),
-    StructId(StructId),
-    TraitId(TraitId),
-    EnumVariantId(EnumVariantId),
+    Function(FunctionId),
+    ImplDef(ImplId),
+    Static(StaticId),
+    Struct(StructId),
+    Union(UnionId),
+    TypeAlias(TypeAliasId),
+    Trait(TraitId),
+    EnumVariant(EnumVariantId),
 }
 
 impl LangItemTarget {
@@ -33,42 +35,42 @@ impl LangItemTarget {
 
     pub fn as_function(self) -> Option<FunctionId> {
         match self {
-            LangItemTarget::FunctionId(id) => Some(id),
+            LangItemTarget::Function(id) => Some(id),
             _ => None,
         }
     }
 
     pub fn as_impl_def(self) -> Option<ImplId> {
         match self {
-            LangItemTarget::ImplDefId(id) => Some(id),
+            LangItemTarget::ImplDef(id) => Some(id),
             _ => None,
         }
     }
 
     pub fn as_static(self) -> Option<StaticId> {
         match self {
-            LangItemTarget::StaticId(id) => Some(id),
+            LangItemTarget::Static(id) => Some(id),
             _ => None,
         }
     }
 
     pub fn as_struct(self) -> Option<StructId> {
         match self {
-            LangItemTarget::StructId(id) => Some(id),
+            LangItemTarget::Struct(id) => Some(id),
             _ => None,
         }
     }
 
     pub fn as_trait(self) -> Option<TraitId> {
         match self {
-            LangItemTarget::TraitId(id) => Some(id),
+            LangItemTarget::Trait(id) => Some(id),
             _ => None,
         }
     }
 
     pub fn as_enum_variant(self) -> Option<EnumVariantId> {
         match self {
-            LangItemTarget::EnumVariantId(id) => Some(id),
+            LangItemTarget::EnumVariant(id) => Some(id),
             _ => None,
         }
     }
@@ -76,12 +78,12 @@ impl LangItemTarget {
 
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
 pub struct LangItems {
-    items: FxHashMap<SmolStr, LangItemTarget>,
+    items: FxHashMap<LangItem, LangItemTarget>,
 }
 
 impl LangItems {
-    pub fn target(&self, item: &str) -> Option<LangItemTarget> {
-        self.items.get(item).copied()
+    pub fn target(&self, item: LangItem) -> Option<LangItemTarget> {
+        self.items.get(&item).copied()
     }
 
     /// Salsa query. This will look for lang items in a specific crate.
@@ -94,16 +96,27 @@ impl LangItems {
 
         for (_, module_data) in crate_def_map.modules() {
             for impl_def in module_data.scope.impls() {
-                lang_items.collect_lang_item(db, impl_def, LangItemTarget::ImplDefId)
+                lang_items.collect_lang_item(db, impl_def, LangItemTarget::ImplDef);
+                for assoc in db.impl_data(impl_def).items.iter().copied() {
+                    match assoc {
+                        AssocItemId::FunctionId(f) => {
+                            lang_items.collect_lang_item(db, f, LangItemTarget::Function)
+                        }
+                        AssocItemId::TypeAliasId(t) => {
+                            lang_items.collect_lang_item(db, t, LangItemTarget::TypeAlias)
+                        }
+                        AssocItemId::ConstId(_) => (),
+                    }
+                }
             }
 
             for def in module_data.scope.declarations() {
                 match def {
                     ModuleDefId::TraitId(trait_) => {
-                        lang_items.collect_lang_item(db, trait_, LangItemTarget::TraitId);
+                        lang_items.collect_lang_item(db, trait_, LangItemTarget::Trait);
                         db.trait_data(trait_).items.iter().for_each(|&(_, assoc_id)| {
-                            if let crate::AssocItemId::FunctionId(f) = assoc_id {
-                                lang_items.collect_lang_item(db, f, LangItemTarget::FunctionId);
+                            if let AssocItemId::FunctionId(f) = assoc_id {
+                                lang_items.collect_lang_item(db, f, LangItemTarget::Function);
                             }
                         });
                     }
@@ -113,18 +126,24 @@ impl LangItems {
                             lang_items.collect_lang_item(
                                 db,
                                 EnumVariantId { parent: e, local_id },
-                                LangItemTarget::EnumVariantId,
+                                LangItemTarget::EnumVariant,
                             );
                         });
                     }
                     ModuleDefId::AdtId(AdtId::StructId(s)) => {
-                        lang_items.collect_lang_item(db, s, LangItemTarget::StructId);
+                        lang_items.collect_lang_item(db, s, LangItemTarget::Struct);
+                    }
+                    ModuleDefId::AdtId(AdtId::UnionId(u)) => {
+                        lang_items.collect_lang_item(db, u, LangItemTarget::Union);
                     }
                     ModuleDefId::FunctionId(f) => {
-                        lang_items.collect_lang_item(db, f, LangItemTarget::FunctionId);
+                        lang_items.collect_lang_item(db, f, LangItemTarget::Function);
                     }
                     ModuleDefId::StaticId(s) => {
-                        lang_items.collect_lang_item(db, s, LangItemTarget::StaticId);
+                        lang_items.collect_lang_item(db, s, LangItemTarget::Static);
+                    }
+                    ModuleDefId::TypeAliasId(t) => {
+                        lang_items.collect_lang_item(db, t, LangItemTarget::TypeAlias);
                     }
                     _ => {}
                 }
@@ -139,7 +158,7 @@ impl LangItems {
     pub(crate) fn lang_item_query(
         db: &dyn DefDatabase,
         start_crate: CrateId,
-        item: SmolStr,
+        item: LangItem,
     ) -> Option<LangItemTarget> {
         let _p = profile::span("lang_item_query");
         let lang_items = db.crate_lang_items(start_crate);
@@ -150,7 +169,7 @@ impl LangItems {
         db.crate_graph()[start_crate]
             .dependencies
             .iter()
-            .find_map(|dep| db.lang_item(dep.crate_id, item.clone()))
+            .find_map(|dep| db.lang_item(dep.crate_id, item))
     }
 
     fn collect_lang_item<T>(
@@ -162,8 +181,8 @@ impl LangItems {
         T: Into<AttrDefId> + Copy,
     {
         let _p = profile::span("collect_lang_item");
-        if let Some(lang_item_name) = lang_attr(db, item) {
-            self.items.entry(lang_item_name).or_insert_with(|| constructor(item));
+        if let Some(lang_item) = lang_attr(db, item).and_then(|it| LangItem::from_str(&it)) {
+            self.items.entry(lang_item).or_insert_with(|| constructor(item));
         }
     }
 }
@@ -172,3 +191,224 @@ pub fn lang_attr(db: &dyn DefDatabase, item: impl Into<AttrDefId> + Copy) -> Opt
     let attrs = db.attrs(item.into());
     attrs.by_key("lang").string_value().cloned()
 }
+
+pub enum GenericRequirement {
+    None,
+    Minimum(usize),
+    Exact(usize),
+}
+
+macro_rules! language_item_table {
+    (
+        $( $(#[$attr:meta])* $variant:ident, $name:ident, $method:ident, $target:expr, $generics:expr; )*
+    ) => {
+
+        /// A representation of all the valid language items in Rust.
+        #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+        pub enum LangItem {
+            $(
+                #[doc = concat!("The `", stringify!($name), "` lang item.")]
+                $(#[$attr])*
+                $variant,
+            )*
+        }
+
+        impl LangItem {
+            pub fn name(self) -> SmolStr {
+                match self {
+                    $( LangItem::$variant => SmolStr::new(stringify!($name)), )*
+                }
+            }
+
+            /// Opposite of [`LangItem::name`]
+            pub fn from_name(name: &hir_expand::name::Name) -> Option<Self> {
+                Self::from_str(name.as_str()?)
+            }
+
+            /// Opposite of [`LangItem::name`]
+            pub fn from_str(name: &str) -> Option<Self> {
+                match name {
+                    $( stringify!($name) => Some(LangItem::$variant), )*
+                    _ => None,
+                }
+            }
+        }
+    }
+}
+
+language_item_table! {
+//  Variant name,            Name,                     Getter method name,         Target                  Generic requirements;
+    Sized,                   sized,               sized_trait,                Target::Trait,          GenericRequirement::Exact(0);
+    Unsize,                  unsize,              unsize_trait,               Target::Trait,          GenericRequirement::Minimum(1);
+    /// Trait injected by `#[derive(PartialEq)]`, (i.e. "Partial EQ").
+    StructuralPeq,           structural_peq,      structural_peq_trait,       Target::Trait,          GenericRequirement::None;
+    /// Trait injected by `#[derive(Eq)]`, (i.e. "Total EQ"; no, I will not apologize).
+    StructuralTeq,           structural_teq,      structural_teq_trait,       Target::Trait,          GenericRequirement::None;
+    Copy,                    copy,                copy_trait,                 Target::Trait,          GenericRequirement::Exact(0);
+    Clone,                   clone,               clone_trait,                Target::Trait,          GenericRequirement::None;
+    Sync,                    sync,                sync_trait,                 Target::Trait,          GenericRequirement::Exact(0);
+    DiscriminantKind,        discriminant_kind,   discriminant_kind_trait,    Target::Trait,          GenericRequirement::None;
+    /// The associated item of the [`DiscriminantKind`] trait.
+    Discriminant,            discriminant_type,   discriminant_type,          Target::AssocTy,        GenericRequirement::None;
+
+    PointeeTrait,            pointee_trait,       pointee_trait,              Target::Trait,          GenericRequirement::None;
+    Metadata,                metadata_type,       metadata_type,              Target::AssocTy,        GenericRequirement::None;
+    DynMetadata,             dyn_metadata,        dyn_metadata,               Target::Struct,         GenericRequirement::None;
+
+    Freeze,                  freeze,              freeze_trait,               Target::Trait,          GenericRequirement::Exact(0);
+
+    Drop,                    drop,                drop_trait,                 Target::Trait,          GenericRequirement::None;
+    Destruct,                destruct,            destruct_trait,             Target::Trait,          GenericRequirement::None;
+
+    CoerceUnsized,           coerce_unsized,      coerce_unsized_trait,       Target::Trait,          GenericRequirement::Minimum(1);
+    DispatchFromDyn,         dispatch_from_dyn,   dispatch_from_dyn_trait,    Target::Trait,          GenericRequirement::Minimum(1);
+
+    // language items relating to transmutability
+    TransmuteOpts,           transmute_opts,      transmute_opts,             Target::Struct,         GenericRequirement::Exact(0);
+    TransmuteTrait,          transmute_trait,     transmute_trait,            Target::Trait,          GenericRequirement::Exact(3);
+
+    Add,                     add,                 add_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Sub,                     sub,                 sub_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Mul,                     mul,                 mul_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Div,                     div,                 div_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Rem,                     rem,                 rem_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Neg,                     neg,                 neg_trait,                  Target::Trait,          GenericRequirement::Exact(0);
+    Not,                     not,                 not_trait,                  Target::Trait,          GenericRequirement::Exact(0);
+    BitXor,                  bitxor,              bitxor_trait,               Target::Trait,          GenericRequirement::Exact(1);
+    BitAnd,                  bitand,              bitand_trait,               Target::Trait,          GenericRequirement::Exact(1);
+    BitOr,                   bitor,               bitor_trait,                Target::Trait,          GenericRequirement::Exact(1);
+    Shl,                     shl,                 shl_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    Shr,                     shr,                 shr_trait,                  Target::Trait,          GenericRequirement::Exact(1);
+    AddAssign,               add_assign,          add_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    SubAssign,               sub_assign,          sub_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    MulAssign,               mul_assign,          mul_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    DivAssign,               div_assign,          div_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    RemAssign,               rem_assign,          rem_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    BitXorAssign,            bitxor_assign,       bitxor_assign_trait,        Target::Trait,          GenericRequirement::Exact(1);
+    BitAndAssign,            bitand_assign,       bitand_assign_trait,        Target::Trait,          GenericRequirement::Exact(1);
+    BitOrAssign,             bitor_assign,        bitor_assign_trait,         Target::Trait,          GenericRequirement::Exact(1);
+    ShlAssign,               shl_assign,          shl_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    ShrAssign,               shr_assign,          shr_assign_trait,           Target::Trait,          GenericRequirement::Exact(1);
+    Index,                   index,               index_trait,                Target::Trait,          GenericRequirement::Exact(1);
+    IndexMut,                index_mut,           index_mut_trait,            Target::Trait,          GenericRequirement::Exact(1);
+
+    UnsafeCell,              unsafe_cell,         unsafe_cell_type,           Target::Struct,         GenericRequirement::None;
+    VaList,                  va_list,             va_list,                    Target::Struct,         GenericRequirement::None;
+
+    Deref,                   deref,               deref_trait,                Target::Trait,          GenericRequirement::Exact(0);
+    DerefMut,                deref_mut,           deref_mut_trait,            Target::Trait,          GenericRequirement::Exact(0);
+    DerefTarget,             deref_target,        deref_target,               Target::AssocTy,        GenericRequirement::None;
+    Receiver,                receiver,            receiver_trait,             Target::Trait,          GenericRequirement::None;
+
+    Fn,                      fn,                  fn_trait,                   Target::Trait,          GenericRequirement::Exact(1);
+    FnMut,                   fn_mut,              fn_mut_trait,               Target::Trait,          GenericRequirement::Exact(1);
+    FnOnce,                  fn_once,             fn_once_trait,              Target::Trait,          GenericRequirement::Exact(1);
+
+    FnOnceOutput,            fn_once_output,      fn_once_output,             Target::AssocTy,        GenericRequirement::None;
+
+    Future,                  future_trait,        future_trait,               Target::Trait,          GenericRequirement::Exact(0);
+    GeneratorState,          generator_state,     gen_state,                  Target::Enum,           GenericRequirement::None;
+    Generator,               generator,           gen_trait,                  Target::Trait,          GenericRequirement::Minimum(1);
+    Unpin,                   unpin,               unpin_trait,                Target::Trait,          GenericRequirement::None;
+    Pin,                     pin,                 pin_type,                   Target::Struct,         GenericRequirement::None;
+
+    PartialEq,               eq,                  eq_trait,                   Target::Trait,          GenericRequirement::Exact(1);
+    PartialOrd,              partial_ord,         partial_ord_trait,          Target::Trait,          GenericRequirement::Exact(1);
+
+    // A number of panic-related lang items. The `panic` item corresponds to divide-by-zero and
+    // various panic cases with `match`. The `panic_bounds_check` item is for indexing arrays.
+    //
+    // The `begin_unwind` lang item has a predefined symbol name and is sort of a "weak lang item"
+    // in the sense that a crate is not required to have it defined to use it, but a final product
+    // is required to define it somewhere. Additionally, there are restrictions on crates that use
+    // a weak lang item, but do not have it defined.
+    Panic,                   panic,               panic_fn,                   Target::Fn,             GenericRequirement::Exact(0);
+    PanicNounwind,           panic_nounwind,      panic_nounwind,             Target::Fn,             GenericRequirement::Exact(0);
+    PanicFmt,                panic_fmt,           panic_fmt,                  Target::Fn,             GenericRequirement::None;
+    PanicDisplay,            panic_display,       panic_display,              Target::Fn,             GenericRequirement::None;
+    ConstPanicFmt,           const_panic_fmt,     const_panic_fmt,            Target::Fn,             GenericRequirement::None;
+    PanicBoundsCheck,        panic_bounds_check,  panic_bounds_check_fn,      Target::Fn,             GenericRequirement::Exact(0);
+    PanicInfo,               panic_info,          panic_info,                 Target::Struct,         GenericRequirement::None;
+    PanicLocation,           panic_location,      panic_location,             Target::Struct,         GenericRequirement::None;
+    PanicImpl,               panic_impl,          panic_impl,                 Target::Fn,             GenericRequirement::None;
+    PanicCannotUnwind,       panic_cannot_unwind, panic_cannot_unwind,        Target::Fn,             GenericRequirement::Exact(0);
+    /// libstd panic entry point. Necessary for const eval to be able to catch it
+    BeginPanic,              begin_panic,         begin_panic_fn,             Target::Fn,             GenericRequirement::None;
+
+    ExchangeMalloc,          exchange_malloc,     exchange_malloc_fn,         Target::Fn,             GenericRequirement::None;
+    BoxFree,                 box_free,            box_free_fn,                Target::Fn,             GenericRequirement::Minimum(1);
+    DropInPlace,             drop_in_place,       drop_in_place_fn,           Target::Fn,             GenericRequirement::Minimum(1);
+    AllocLayout,             alloc_layout,        alloc_layout,               Target::Struct,         GenericRequirement::None;
+
+    Start,                   start,               start_fn,                   Target::Fn,             GenericRequirement::Exact(1);
+
+    EhPersonality,           eh_personality,      eh_personality,             Target::Fn,             GenericRequirement::None;
+    EhCatchTypeinfo,         eh_catch_typeinfo,   eh_catch_typeinfo,          Target::Static,         GenericRequirement::None;
+
+    OwnedBox,                owned_box,           owned_box,                  Target::Struct,         GenericRequirement::Minimum(1);
+
+    PhantomData,             phantom_data,        phantom_data,               Target::Struct,         GenericRequirement::Exact(1);
+
+    ManuallyDrop,            manually_drop,       manually_drop,              Target::Struct,         GenericRequirement::None;
+
+    MaybeUninit,             maybe_uninit,        maybe_uninit,               Target::Union,          GenericRequirement::None;
+
+    /// Align offset for stride != 1; must not panic.
+    AlignOffset,             align_offset,        align_offset_fn,            Target::Fn,             GenericRequirement::None;
+
+    Termination,             termination,         termination,                Target::Trait,          GenericRequirement::None;
+
+    Try,                     Try,                 try_trait,                  Target::Trait,          GenericRequirement::None;
+
+    Tuple,                   tuple_trait,         tuple_trait,                Target::Trait,          GenericRequirement::Exact(0);
+
+    SliceLen,                slice_len_fn,        slice_len_fn,               Target::Method(MethodKind::Inherent), GenericRequirement::None;
+
+    // Language items from AST lowering
+    TryTraitFromResidual,    from_residual,       from_residual_fn,           Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+    TryTraitFromOutput,      from_output,         from_output_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+    TryTraitBranch,          branch,              branch_fn,                  Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+    TryTraitFromYeet,        from_yeet,           from_yeet_fn,               Target::Fn,             GenericRequirement::None;
+
+    PointerSized,            pointer_sized,       pointer_sized,              Target::Trait,          GenericRequirement::Exact(0);
+
+    Poll,                    Poll,                poll,                       Target::Enum,           GenericRequirement::None;
+    PollReady,               Ready,               poll_ready_variant,         Target::Variant,        GenericRequirement::None;
+    PollPending,             Pending,             poll_pending_variant,       Target::Variant,        GenericRequirement::None;
+
+    // FIXME(swatinem): the following lang items are used for async lowering and
+    // should become obsolete eventually.
+    ResumeTy,                ResumeTy,            resume_ty,                  Target::Struct,         GenericRequirement::None;
+    IdentityFuture,          identity_future,     identity_future_fn,         Target::Fn,             GenericRequirement::None;
+    GetContext,              get_context,         get_context_fn,             Target::Fn,             GenericRequirement::None;
+
+    Context,                 Context,             context,                    Target::Struct,         GenericRequirement::None;
+    FuturePoll,              poll,                future_poll_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+
+    FromFrom,                from,                from_fn,                    Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+
+    OptionSome,              Some,                option_some_variant,        Target::Variant,        GenericRequirement::None;
+    OptionNone,              None,                option_none_variant,        Target::Variant,        GenericRequirement::None;
+
+    ResultOk,                Ok,                  result_ok_variant,          Target::Variant,        GenericRequirement::None;
+    ResultErr,               Err,                 result_err_variant,         Target::Variant,        GenericRequirement::None;
+
+    ControlFlowContinue,     Continue,            cf_continue_variant,        Target::Variant,        GenericRequirement::None;
+    ControlFlowBreak,        Break,               cf_break_variant,           Target::Variant,        GenericRequirement::None;
+
+    IntoFutureIntoFuture,    into_future,         into_future_fn,             Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+    IntoIterIntoIter,        into_iter,           into_iter_fn,               Target::Method(MethodKind::Trait { body: false }), GenericRequirement::None;
+    IteratorNext,            next,                next_fn,                    Target::Method(MethodKind::Trait { body: false}), GenericRequirement::None;
+
+    PinNewUnchecked,         new_unchecked,       new_unchecked_fn,           Target::Method(MethodKind::Inherent), GenericRequirement::None;
+
+    RangeFrom,               RangeFrom,           range_from_struct,          Target::Struct,         GenericRequirement::None;
+    RangeFull,               RangeFull,           range_full_struct,          Target::Struct,         GenericRequirement::None;
+    RangeInclusiveStruct,    RangeInclusive,      range_inclusive_struct,     Target::Struct,         GenericRequirement::None;
+    RangeInclusiveNew,       range_inclusive_new, range_inclusive_new_method, Target::Method(MethodKind::Inherent), GenericRequirement::None;
+    Range,                   Range,               range_struct,               Target::Struct,         GenericRequirement::None;
+    RangeToInclusive,        RangeToInclusive,    range_to_inclusive_struct,  Target::Struct,         GenericRequirement::None;
+    RangeTo,                 RangeTo,             range_to_struct,            Target::Struct,         GenericRequirement::None;
+
+    String,                  String,              string,                     Target::Struct,         GenericRequirement::None;
+}
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/layout.rs b/src/tools/rust-analyzer/crates/hir-def/src/layout.rs
index 6bb4cd94f..49b1190ad 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/layout.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/layout.rs
@@ -90,6 +90,7 @@ impl IntegerExt for Integer {
 pub enum LayoutError {
     UserError(String),
     SizeOverflow,
+    TargetLayoutNotAvailable,
     HasPlaceholder,
     NotImplemented,
     Unknown,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/lib.rs b/src/tools/rust-analyzer/crates/hir-def/src/lib.rs
index 8267ef09c..d07c5fb67 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/lib.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/lib.rs
@@ -28,7 +28,6 @@ pub mod dyn_map;
 pub mod keys;
 
 pub mod item_tree;
-pub mod intern;
 
 pub mod adt;
 pub mod data;
@@ -61,10 +60,10 @@ use std::{
     sync::Arc,
 };
 
-use attr::Attr;
 use base_db::{impl_intern_key, salsa, CrateId, ProcMacroKind};
 use hir_expand::{
     ast_id_map::FileAstId,
+    attrs::{Attr, AttrId, AttrInput},
     builtin_attr_macro::BuiltinAttrExpander,
     builtin_derive_macro::BuiltinDeriveExpander,
     builtin_fn_macro::{BuiltinFnLikeExpander, EagerExpander},
@@ -80,9 +79,10 @@ use nameres::DefMap;
 use stdx::impl_from;
 use syntax::ast;
 
+use ::tt::token_id as tt;
+
 use crate::{
     adt::VariantData,
-    attr::AttrId,
     builtin_type::BuiltinType,
     item_tree::{
         Const, Enum, Function, Impl, ItemTreeId, ItemTreeNode, MacroDef, MacroRules, ModItem,
@@ -292,6 +292,7 @@ pub struct Macro2Loc {
     pub container: ModuleId,
     pub id: ItemTreeId<MacroDef>,
     pub expander: MacroExpander,
+    pub allow_internal_unsafe: bool,
 }
 impl_intern!(Macro2Id, Macro2Loc, intern_macro2, lookup_intern_macro2);
 
@@ -301,8 +302,9 @@ pub struct MacroRulesId(salsa::InternId);
 pub struct MacroRulesLoc {
     pub container: ModuleId,
     pub id: ItemTreeId<MacroRules>,
-    pub local_inner: bool,
     pub expander: MacroExpander,
+    pub allow_internal_unsafe: bool,
+    pub local_inner: bool,
 }
 impl_intern!(MacroRulesId, MacroRulesLoc, intern_macro_rules, lookup_intern_macro_rules);
 
@@ -896,6 +898,7 @@ pub fn macro_id_to_def_id(db: &dyn db::DefDatabase, id: MacroId) -> MacroDefId {
                     }
                 },
                 local_inner: false,
+                allow_internal_unsafe: loc.allow_internal_unsafe,
             }
         }
         MacroId::MacroRulesId(it) => {
@@ -920,6 +923,7 @@ pub fn macro_id_to_def_id(db: &dyn db::DefDatabase, id: MacroId) -> MacroDefId {
                     }
                 },
                 local_inner: loc.local_inner,
+                allow_internal_unsafe: loc.allow_internal_unsafe,
             }
         }
         MacroId::ProcMacroId(it) => {
@@ -935,6 +939,7 @@ pub fn macro_id_to_def_id(db: &dyn db::DefDatabase, id: MacroId) -> MacroDefId {
                     InFile::new(loc.id.file_id(), makro.ast_id),
                 ),
                 local_inner: false,
+                allow_internal_unsafe: false,
             }
         }
     }
@@ -943,7 +948,7 @@ pub fn macro_id_to_def_id(db: &dyn db::DefDatabase, id: MacroId) -> MacroDefId {
 fn derive_macro_as_call_id(
     db: &dyn db::DefDatabase,
     item_attr: &AstIdWithPath<ast::Adt>,
-    derive_attr: AttrId,
+    derive_attr_index: AttrId,
     derive_pos: u32,
     krate: CrateId,
     resolver: impl Fn(path::ModPath) -> Option<(MacroId, MacroDefId)>,
@@ -956,7 +961,7 @@ fn derive_macro_as_call_id(
         MacroCallKind::Derive {
             ast_id: item_attr.ast_id,
             derive_index: derive_pos,
-            derive_attr_index: derive_attr.ast_index,
+            derive_attr_index,
         },
     );
     Ok((macro_id, def_id, call_id))
@@ -970,23 +975,33 @@ fn attr_macro_as_call_id(
     def: MacroDefId,
     is_derive: bool,
 ) -> MacroCallId {
-    let mut arg = match macro_attr.input.as_deref() {
-        Some(attr::AttrInput::TokenTree(tt, map)) => (tt.clone(), map.clone()),
-        _ => Default::default(),
+    let arg = match macro_attr.input.as_deref() {
+        Some(AttrInput::TokenTree(tt, map)) => (
+            {
+                let mut tt = tt.clone();
+                tt.delimiter = tt::Delimiter::UNSPECIFIED;
+                tt
+            },
+            map.clone(),
+        ),
+        _ => (tt::Subtree::empty(), Default::default()),
     };
 
-    // The parentheses are always disposed here.
-    arg.0.delimiter = None;
-
-    let res = def.as_lazy_macro(
+    def.as_lazy_macro(
         db.upcast(),
         krate,
         MacroCallKind::Attr {
             ast_id: item_attr.ast_id,
             attr_args: Arc::new(arg),
-            invoc_attr_index: macro_attr.id.ast_index,
+            invoc_attr_index: macro_attr.id,
             is_derive,
         },
-    );
-    res
-}
+    )
+}
+intern::impl_internable!(
+    crate::type_ref::TypeRef,
+    crate::type_ref::TraitRef,
+    crate::type_ref::TypeBound,
+    crate::path::GenericArgs,
+    generics::GenericParams,
+);
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests.rs b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests.rs
index 79c85d118..5ab90d92d 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests.rs
@@ -30,7 +30,7 @@ use syntax::{
     SyntaxKind::{self, COMMENT, EOF, IDENT, LIFETIME_IDENT},
     SyntaxNode, TextRange, T,
 };
-use tt::{Subtree, TokenId};
+use tt::token_id::{Subtree, TokenId};
 
 use crate::{
     db::DefDatabase, macro_id_to_def_id, nameres::ModuleSource, resolver::HasResolver,
@@ -97,7 +97,9 @@ pub fn identity_when_valid(_attr: TokenStream, item: TokenStream) -> TokenStream
         let ast_id = AstId::new(source.file_id, file_ast_id.upcast());
         let kind = MacroDefKind::Declarative(ast_id);
 
-        let macro_def = db.macro_def(MacroDefId { krate, kind, local_inner: false }).unwrap();
+        let macro_def = db
+            .macro_def(MacroDefId { krate, kind, local_inner: false, allow_internal_unsafe: false })
+            .unwrap();
         if let TokenExpander::DeclarativeMacro { mac, def_site_token_map } = &*macro_def {
             let tt = match &macro_ {
                 ast::Macro::MacroRules(mac) => mac.token_tree().unwrap(),
@@ -251,9 +253,9 @@ fn extract_id_ranges(ranges: &mut Vec<(TextRange, TokenId)>, map: &TokenMap, tre
     tree.token_trees.iter().for_each(|tree| match tree {
         tt::TokenTree::Leaf(leaf) => {
             let id = match leaf {
-                tt::Leaf::Literal(it) => it.id,
-                tt::Leaf::Punct(it) => it.id,
-                tt::Leaf::Ident(it) => it.id,
+                tt::Leaf::Literal(it) => it.span,
+                tt::Leaf::Punct(it) => it.span,
+                tt::Leaf::Ident(it) => it.span,
             };
             ranges.extend(map.ranges_by_token(id, SyntaxKind::ERROR).map(|range| (range, id)));
         }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs
index 2d5f2a692..7a3e8c3b0 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe.rs
@@ -97,6 +97,41 @@ fn#19 main#20(#21)#21 {#22
 "##]],
     );
 }
+#[test]
+fn float_field_acces_macro_input() {
+    check(
+        r#"
+macro_rules! foo {
+    ($expr:expr) => {
+        fn foo() {
+            $expr;
+        }
+    };
+}
+foo!(x .0.1);
+foo!(x .2. 3);
+foo!(x .4 .5);
+"#,
+        expect![[r#"
+macro_rules! foo {
+    ($expr:expr) => {
+        fn foo() {
+            $expr;
+        }
+    };
+}
+fn foo() {
+    (x.0.1);
+}
+fn foo() {
+    (x.2.3);
+}
+fn foo() {
+    (x.4.5);
+}
+"#]],
+    );
+}
 
 #[test]
 fn mbe_smoke_test() {
@@ -1441,7 +1476,7 @@ macro_rules! m {
 /* parse error: expected identifier */
 /* parse error: expected SEMICOLON */
 /* parse error: expected SEMICOLON */
-/* parse error: expected expression */
+/* parse error: expected expression, item or let statement */
 fn f() {
     K::(C("0"));
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
index d2505e7ca..8358a46f0 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/mbe/regression.rs
@@ -830,8 +830,7 @@ macro_rules! rgb_color {
 /* parse error: expected COMMA */
 /* parse error: expected R_ANGLE */
 /* parse error: expected SEMICOLON */
-/* parse error: expected SEMICOLON */
-/* parse error: expected expression */
+/* parse error: expected expression, item or let statement */
 pub fn new() {
     let _ = 0as u32<<(8+8);
 }
@@ -848,21 +847,21 @@ pub fn new() {
 //     BLOCK_EXPR@10..31
 //       STMT_LIST@10..31
 //         L_CURLY@10..11 "{"
-//         LET_STMT@11..27
+//         LET_STMT@11..28
 //           LET_KW@11..14 "let"
 //           WILDCARD_PAT@14..15
 //             UNDERSCORE@14..15 "_"
 //           EQ@15..16 "="
-//           CAST_EXPR@16..27
+//           CAST_EXPR@16..28
 //             LITERAL@16..17
 //               INT_NUMBER@16..17 "0"
 //             AS_KW@17..19 "as"
-//             PATH_TYPE@19..27
-//               PATH@19..27
-//                 PATH_SEGMENT@19..27
+//             PATH_TYPE@19..28
+//               PATH@19..28
+//                 PATH_SEGMENT@19..28
 //                   NAME_REF@19..22
 //                     IDENT@19..22 "u32"
-//                   GENERIC_ARG_LIST@22..27
+//                   GENERIC_ARG_LIST@22..28
 //                     L_ANGLE@22..23 "<"
 //                     TYPE_ARG@23..27
 //                       DYN_TRAIT_TYPE@23..27
@@ -877,9 +876,9 @@ pub fn new() {
 //                                     ERROR@25..26
 //                                       INT_NUMBER@25..26 "8"
 //                           PLUS@26..27 "+"
-//         EXPR_STMT@27..28
-//           LITERAL@27..28
-//             INT_NUMBER@27..28 "8"
+//                     CONST_ARG@27..28
+//                       LITERAL@27..28
+//                         INT_NUMBER@27..28 "8"
 //         ERROR@28..29
 //           R_PAREN@28..29 ")"
 //         SEMICOLON@29..30 ";"
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/proc_macros.rs b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/proc_macros.rs
index 118c14ed8..822bdcc12 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/proc_macros.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/macro_expansion_tests/proc_macros.rs
@@ -104,7 +104,7 @@ macro_rules! id {
         $($t)*
     };
 }
-id /*+errors*/! {
+id! {
     #[proc_macros::identity]
     impl Foo for WrapBj {
         async fn foo(&self) {
@@ -113,18 +113,17 @@ id /*+errors*/! {
     }
 }
 "#,
-        expect![[r##"
+        expect![[r#"
 macro_rules! id {
     ($($t:tt)*) => {
         $($t)*
     };
 }
-/* parse error: expected SEMICOLON */
 #[proc_macros::identity] impl Foo for WrapBj {
     async fn foo(&self ) {
         self .0.id().await ;
     }
 }
-"##]],
+"#]],
     );
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/attr_resolution.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/attr_resolution.rs
index 3650204ee..79cabeb0f 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/attr_resolution.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/attr_resolution.rs
@@ -1,10 +1,9 @@
 //! Post-nameres attribute resolution.
 
-use hir_expand::MacroCallId;
+use hir_expand::{attrs::Attr, MacroCallId};
 use syntax::{ast, SmolStr};
 
 use crate::{
-    attr::Attr,
     attr_macro_as_call_id, builtin_attr,
     db::DefDatabase,
     item_scope::BuiltinShadowMode,
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs
index 160203b77..4b39a20d8 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/collector.rs
@@ -10,6 +10,7 @@ use cfg::{CfgExpr, CfgOptions};
 use either::Either;
 use hir_expand::{
     ast_id_map::FileAstId,
+    attrs::{Attr, AttrId},
     builtin_attr_macro::find_builtin_attr,
     builtin_derive_macro::find_builtin_derive,
     builtin_fn_macro::find_builtin_macro,
@@ -26,7 +27,7 @@ use stdx::always;
 use syntax::{ast, SmolStr};
 
 use crate::{
-    attr::{Attr, AttrId, Attrs},
+    attr::Attrs,
     attr_macro_as_call_id,
     db::DefDatabase,
     derive_macro_as_call_id,
@@ -45,6 +46,7 @@ use crate::{
     },
     path::{ImportAlias, ModPath, PathKind},
     per_ns::PerNs,
+    tt,
     visibility::{RawVisibility, Visibility},
     AdtId, AstId, AstIdWithPath, ConstLoc, EnumLoc, EnumVariantId, ExternBlockLoc, FunctionId,
     FunctionLoc, ImplLoc, Intern, ItemContainerId, LocalModuleId, Macro2Id, Macro2Loc,
@@ -82,7 +84,8 @@ pub(super) fn collect_defs(db: &dyn DefDatabase, mut def_map: DefMap, tree_id: T
                 .enumerate()
                 .map(|(idx, it)| {
                     // FIXME: a hacky way to create a Name from string.
-                    let name = tt::Ident { text: it.name.clone(), id: tt::TokenId::unspecified() };
+                    let name =
+                        tt::Ident { text: it.name.clone(), span: tt::TokenId::unspecified() };
                     (
                         name.as_name(),
                         ProcMacroExpander::new(def_map.krate, base_db::ProcMacroId(idx as u32)),
@@ -450,8 +453,11 @@ impl DefCollector<'_> {
                         directive.module_id,
                         MacroCallKind::Attr {
                             ast_id: ast_id.ast_id,
-                            attr_args: Default::default(),
-                            invoc_attr_index: attr.id.ast_index,
+                            attr_args: std::sync::Arc::new((
+                                tt::Subtree::empty(),
+                                Default::default(),
+                            )),
+                            invoc_attr_index: attr.id,
                             is_derive: false,
                         },
                         attr.path().clone(),
@@ -1406,7 +1412,7 @@ impl DefCollector<'_> {
                         directive.module_id,
                         MacroCallKind::Derive {
                             ast_id: ast_id.ast_id,
-                            derive_attr_index: derive_attr.ast_index,
+                            derive_attr_index: *derive_attr,
                             derive_index: *derive_pos as u32,
                         },
                         ast_id.path.clone(),
@@ -1599,17 +1605,15 @@ impl ModCollector<'_, '_> {
                         FunctionLoc { container, id: ItemTreeId::new(self.tree_id, id) }.intern(db);
 
                     let vis = resolve_vis(def_map, &self.item_tree[it.visibility]);
-                    if self.def_collector.is_proc_macro {
-                        if self.module_id == def_map.root {
-                            if let Some(proc_macro) = attrs.parse_proc_macro_decl(&it.name) {
-                                let crate_root = def_map.module_id(def_map.root);
-                                self.def_collector.export_proc_macro(
-                                    proc_macro,
-                                    ItemTreeId::new(self.tree_id, id),
-                                    fn_id,
-                                    crate_root,
-                                );
-                            }
+                    if self.def_collector.is_proc_macro && self.module_id == def_map.root {
+                        if let Some(proc_macro) = attrs.parse_proc_macro_decl(&it.name) {
+                            let crate_root = def_map.module_id(def_map.root);
+                            self.def_collector.export_proc_macro(
+                                proc_macro,
+                                ItemTreeId::new(self.tree_id, id),
+                                fn_id,
+                                crate_root,
+                            );
                         }
                     }
 
@@ -1948,7 +1952,8 @@ impl ModCollector<'_, '_> {
             let name = match attrs.by_key("rustc_builtin_macro").string_value() {
                 Some(it) => {
                     // FIXME: a hacky way to create a Name from string.
-                    name = tt::Ident { text: it.clone(), id: tt::TokenId::unspecified() }.as_name();
+                    name =
+                        tt::Ident { text: it.clone(), span: tt::TokenId::unspecified() }.as_name();
                     &name
                 }
                 None => {
@@ -1983,11 +1988,13 @@ impl ModCollector<'_, '_> {
             // Case 2: normal `macro_rules!` macro
             MacroExpander::Declarative
         };
+        let allow_internal_unsafe = attrs.by_key("allow_internal_unsafe").exists();
 
         let macro_id = MacroRulesLoc {
             container: module,
             id: ItemTreeId::new(self.tree_id, id),
             local_inner,
+            allow_internal_unsafe,
             expander,
         }
         .intern(self.def_collector.db);
@@ -2047,10 +2054,15 @@ impl ModCollector<'_, '_> {
             // Case 2: normal `macro`
             MacroExpander::Declarative
         };
+        let allow_internal_unsafe = attrs.by_key("allow_internal_unsafe").exists();
 
-        let macro_id =
-            Macro2Loc { container: module, id: ItemTreeId::new(self.tree_id, id), expander }
-                .intern(self.def_collector.db);
+        let macro_id = Macro2Loc {
+            container: module,
+            id: ItemTreeId::new(self.tree_id, id),
+            expander,
+            allow_internal_unsafe,
+        }
+        .intern(self.def_collector.db);
         self.def_collector.define_macro_def(
             self.module_id,
             mac.name.clone(),
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/diagnostics.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/diagnostics.rs
index 066142291..b024d7c67 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/diagnostics.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/diagnostics.rs
@@ -2,12 +2,11 @@
 
 use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
-use hir_expand::MacroCallKind;
+use hir_expand::{attrs::AttrId, MacroCallKind};
 use la_arena::Idx;
 use syntax::ast::{self, AnyHasAttrs};
 
 use crate::{
-    attr::AttrId,
     item_tree::{self, ItemTreeId},
     nameres::LocalModuleId,
     path::ModPath,
@@ -32,9 +31,9 @@ pub enum DefDiagnosticKind {
 
     UnimplementedBuiltinMacro { ast: AstId<ast::Macro> },
 
-    InvalidDeriveTarget { ast: AstId<ast::Item>, id: u32 },
+    InvalidDeriveTarget { ast: AstId<ast::Item>, id: usize },
 
-    MalformedDerive { ast: AstId<ast::Adt>, id: u32 },
+    MalformedDerive { ast: AstId<ast::Adt>, id: usize },
 }
 
 #[derive(Debug, PartialEq, Eq)]
@@ -120,7 +119,7 @@ impl DefDiagnostic {
     ) -> Self {
         Self {
             in_module: container,
-            kind: DefDiagnosticKind::InvalidDeriveTarget { ast, id: id.ast_index },
+            kind: DefDiagnosticKind::InvalidDeriveTarget { ast, id: id.ast_index() },
         }
     }
 
@@ -131,7 +130,7 @@ impl DefDiagnostic {
     ) -> Self {
         Self {
             in_module: container,
-            kind: DefDiagnosticKind::MalformedDerive { ast, id: id.ast_index },
+            kind: DefDiagnosticKind::MalformedDerive { ast, id: id.ast_index() },
         }
     }
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/mod_resolution.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/mod_resolution.rs
index 4c263846d..51c565fe1 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/mod_resolution.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/mod_resolution.rs
@@ -7,7 +7,7 @@ use syntax::SmolStr;
 
 use crate::{db::DefDatabase, HirFileId};
 
-const MOD_DEPTH_LIMIT: Limit = Limit::new(32);
+static MOD_DEPTH_LIMIT: Limit = Limit::new(32);
 
 #[derive(Clone, Debug)]
 pub(super) struct ModDir {
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/proc_macro.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/proc_macro.rs
index 06b23392c..caad4a1f3 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/proc_macro.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/proc_macro.rs
@@ -1,9 +1,9 @@
 //! Nameres-specific procedural macro data and helpers.
 
 use hir_expand::name::{AsName, Name};
-use tt::{Leaf, TokenTree};
 
 use crate::attr::Attrs;
+use crate::tt::{Leaf, TokenTree};
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct ProcMacroDef {
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests.rs
index 0d90047c2..8a27c60df 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests.rs
@@ -476,7 +476,7 @@ pub struct Bar;
 fn no_std_prelude() {
     check(
         r#"
-        //- /main.rs crate:main deps:core,std
+        //- /main.rs edition:2018 crate:main deps:core,std
         #![cfg_attr(not(never), no_std)]
         use Rust;
 
@@ -544,7 +544,7 @@ fn edition_specific_preludes() {
 fn std_prelude_takes_precedence_above_core_prelude() {
     check(
         r#"
-//- /main.rs crate:main deps:core,std
+//- /main.rs edition:2018 crate:main deps:core,std
 use {Foo, Bar};
 
 //- /std.rs crate:std deps:core
@@ -574,7 +574,7 @@ pub mod prelude {
 fn cfg_not_test() {
     check(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 use {Foo, Bar, Baz};
 
 //- /lib.rs crate:std
@@ -602,7 +602,7 @@ pub mod prelude {
 fn cfg_test() {
     check(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 use {Foo, Bar, Baz};
 
 //- /lib.rs crate:std cfg:test,feature=foo,feature=bar,opt=42
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/macros.rs b/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/macros.rs
index fe0ad4f38..a4ccd14cb 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/macros.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/nameres/tests/macros.rs
@@ -264,7 +264,7 @@ fn prelude_is_macro_use() {
     cov_mark::check!(prelude_is_macro_use);
     check(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 structs!(Foo);
 structs_priv!(Bar);
 structs_outside!(Out);
@@ -634,7 +634,7 @@ fn macro_dollar_crate_is_correct_in_indirect_deps() {
     // From std
     check(
         r#"
-//- /main.rs crate:main deps:std
+//- /main.rs edition:2018 crate:main deps:std
 foo!();
 
 //- /std.rs crate:std deps:core
@@ -1034,7 +1034,7 @@ structs!(Foo);
 fn macro_in_prelude() {
     check(
         r#"
-//- /lib.rs crate:lib deps:std
+//- /lib.rs edition:2018 crate:lib deps:std
 global_asm!();
 
 //- /std.rs crate:std
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/path.rs b/src/tools/rust-analyzer/crates/hir-def/src/path.rs
index 592223f7d..36d4c36a2 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/path.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/path.rs
@@ -8,10 +8,10 @@ use std::{
 
 use crate::{
     body::LowerCtx,
-    intern::Interned,
     type_ref::{ConstScalarOrPath, LifetimeRef},
 };
 use hir_expand::name::Name;
+use intern::Interned;
 use syntax::ast;
 
 use crate::type_ref::{TypeBound, TypeRef};
@@ -38,18 +38,18 @@ impl Display for ImportAlias {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Path {
     /// Type based path like `<T>::foo`.
-    /// Note that paths like `<Type as Trait>::foo` are desugard to `Trait::<Self=Type>::foo`.
+    /// Note that paths like `<Type as Trait>::foo` are desugared to `Trait::<Self=Type>::foo`.
     type_anchor: Option<Interned<TypeRef>>,
     mod_path: Interned<ModPath>,
-    /// Invariant: the same len as `self.mod_path.segments`
-    generic_args: Box<[Option<Interned<GenericArgs>>]>,
+    /// Invariant: the same len as `self.mod_path.segments` or `None` if all segments are `None`.
+    generic_args: Option<Box<[Option<Interned<GenericArgs>>]>>,
 }
 
 /// Generic arguments to a path segment (e.g. the `i32` in `Option<i32>`). This
 /// also includes bindings of associated types, like in `Iterator<Item = Foo>`.
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct GenericArgs {
-    pub args: Vec<GenericArg>,
+    pub args: Box<[GenericArg]>,
     /// This specifies whether the args contain a Self type as the first
     /// element. This is the case for path segments like `<T as Trait>`, where
     /// `T` is actually a type parameter for the path `Trait` specifying the
@@ -57,7 +57,7 @@ pub struct GenericArgs {
     /// is left out.
     pub has_self_type: bool,
     /// Associated type bindings like in `Iterator<Item = T>`.
-    pub bindings: Vec<AssociatedTypeBinding>,
+    pub bindings: Box<[AssociatedTypeBinding]>,
     /// Whether these generic args were desugared from `Trait(Arg) -> Output`
     /// parenthesis notation typically used for the `Fn` traits.
     pub desugared_from_fn: bool,
@@ -77,7 +77,7 @@ pub struct AssociatedTypeBinding {
     /// Bounds for the associated type, like in `Iterator<Item:
     /// SomeOtherTrait>`. (This is the unstable `associated_type_bounds`
     /// feature.)
-    pub bounds: Vec<Interned<TypeBound>>,
+    pub bounds: Box<[Interned<TypeBound>]>,
 }
 
 /// A single generic argument.
@@ -102,7 +102,7 @@ impl Path {
     ) -> Path {
         let generic_args = generic_args.into();
         assert_eq!(path.len(), generic_args.len());
-        Path { type_anchor: None, mod_path: Interned::new(path), generic_args }
+        Path { type_anchor: None, mod_path: Interned::new(path), generic_args: Some(generic_args) }
     }
 
     pub fn kind(&self) -> &PathKind {
@@ -114,7 +114,14 @@ impl Path {
     }
 
     pub fn segments(&self) -> PathSegments<'_> {
-        PathSegments { segments: self.mod_path.segments(), generic_args: &self.generic_args }
+        let s = PathSegments {
+            segments: self.mod_path.segments(),
+            generic_args: self.generic_args.as_deref(),
+        };
+        if let Some(generic_args) = s.generic_args {
+            assert_eq!(s.segments.len(), generic_args.len());
+        }
+        s
     }
 
     pub fn mod_path(&self) -> &ModPath {
@@ -131,13 +138,15 @@ impl Path {
                 self.mod_path.kind,
                 self.mod_path.segments()[..self.mod_path.segments().len() - 1].iter().cloned(),
             )),
-            generic_args: self.generic_args[..self.generic_args.len() - 1].to_vec().into(),
+            generic_args: self.generic_args.as_ref().map(|it| it[..it.len() - 1].to_vec().into()),
         };
         Some(res)
     }
 
     pub fn is_self_type(&self) -> bool {
-        self.type_anchor.is_none() && *self.generic_args == [None] && self.mod_path.is_Self()
+        self.type_anchor.is_none()
+            && self.generic_args.as_deref().is_none()
+            && self.mod_path.is_Self()
     }
 }
 
@@ -149,11 +158,11 @@ pub struct PathSegment<'a> {
 
 pub struct PathSegments<'a> {
     segments: &'a [Name],
-    generic_args: &'a [Option<Interned<GenericArgs>>],
+    generic_args: Option<&'a [Option<Interned<GenericArgs>>]>,
 }
 
 impl<'a> PathSegments<'a> {
-    pub const EMPTY: PathSegments<'static> = PathSegments { segments: &[], generic_args: &[] };
+    pub const EMPTY: PathSegments<'static> = PathSegments { segments: &[], generic_args: None };
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -167,26 +176,29 @@ impl<'a> PathSegments<'a> {
         self.get(self.len().checked_sub(1)?)
     }
     pub fn get(&self, idx: usize) -> Option<PathSegment<'a>> {
-        assert_eq!(self.segments.len(), self.generic_args.len());
         let res = PathSegment {
             name: self.segments.get(idx)?,
-            args_and_bindings: self.generic_args.get(idx).unwrap().as_ref().map(|it| &**it),
+            args_and_bindings: self.generic_args.and_then(|it| it.get(idx)?.as_deref()),
         };
         Some(res)
     }
     pub fn skip(&self, len: usize) -> PathSegments<'a> {
-        assert_eq!(self.segments.len(), self.generic_args.len());
-        PathSegments { segments: &self.segments[len..], generic_args: &self.generic_args[len..] }
+        PathSegments {
+            segments: &self.segments.get(len..).unwrap_or(&[]),
+            generic_args: self.generic_args.and_then(|it| it.get(len..)),
+        }
     }
     pub fn take(&self, len: usize) -> PathSegments<'a> {
-        assert_eq!(self.segments.len(), self.generic_args.len());
-        PathSegments { segments: &self.segments[..len], generic_args: &self.generic_args[..len] }
+        PathSegments {
+            segments: &self.segments.get(..len).unwrap_or(&self.segments),
+            generic_args: self.generic_args.map(|it| it.get(..len).unwrap_or(it)),
+        }
     }
     pub fn iter(&self) -> impl Iterator<Item = PathSegment<'a>> {
-        self.segments.iter().zip(self.generic_args.iter()).map(|(name, args)| PathSegment {
-            name,
-            args_and_bindings: args.as_ref().map(|it| &**it),
-        })
+        self.segments
+            .iter()
+            .zip(self.generic_args.into_iter().flatten().chain(iter::repeat(&None)))
+            .map(|(name, args)| PathSegment { name, args_and_bindings: args.as_deref() })
     }
 }
 
@@ -200,9 +212,9 @@ impl GenericArgs {
 
     pub(crate) fn empty() -> GenericArgs {
         GenericArgs {
-            args: Vec::new(),
+            args: Box::default(),
             has_self_type: false,
-            bindings: Vec::new(),
+            bindings: Box::default(),
             desugared_from_fn: false,
         }
     }
@@ -213,7 +225,7 @@ impl From<Name> for Path {
         Path {
             type_anchor: None,
             mod_path: Interned::new(ModPath::from_segments(PathKind::Plain, iter::once(name))),
-            generic_args: Box::new([None]),
+            generic_args: None,
         }
     }
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/path/lower.rs b/src/tools/rust-analyzer/crates/hir-def/src/path/lower.rs
index cfa3a6baa..c85a11db6 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/path/lower.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/path/lower.rs
@@ -1,9 +1,12 @@
 //! Transforms syntax into `Path` objects, ideally with accounting for hygiene
 
-use crate::{intern::Interned, type_ref::ConstScalarOrPath};
+use std::iter;
+
+use crate::type_ref::ConstScalarOrPath;
 
 use either::Either;
 use hir_expand::name::{name, AsName};
+use intern::Interned;
 use syntax::ast::{self, AstNode, HasTypeBounds};
 
 use super::AssociatedTypeBinding;
@@ -44,8 +47,11 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path
                                 )
                             })
                             .map(Interned::new);
+                        if let Some(_) = args {
+                            generic_args.resize(segments.len(), None);
+                            generic_args.push(args);
+                        }
                         segments.push(name);
-                        generic_args.push(args)
                     }
                     Either::Right(crate_id) => {
                         kind = PathKind::DollarCrate(crate_id);
@@ -55,7 +61,6 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path
             }
             ast::PathSegmentKind::SelfTypeKw => {
                 segments.push(name![Self]);
-                generic_args.push(None)
             }
             ast::PathSegmentKind::Type { type_ref, trait_ref } => {
                 assert!(path.qualifier().is_none()); // this can only occur at the first segment
@@ -76,18 +81,33 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path
                         kind = mod_path.kind;
 
                         segments.extend(mod_path.segments().iter().cloned().rev());
-                        generic_args.extend(Vec::from(path_generic_args).into_iter().rev());
+                        if let Some(path_generic_args) = path_generic_args {
+                            generic_args.resize(segments.len() - num_segments, None);
+                            generic_args.extend(Vec::from(path_generic_args).into_iter().rev());
+                        } else {
+                            generic_args.resize(segments.len(), None);
+                        }
+
+                        let self_type = GenericArg::Type(self_type);
 
                         // Insert the type reference (T in the above example) as Self parameter for the trait
-                        let last_segment =
-                            generic_args.iter_mut().rev().nth(num_segments.saturating_sub(1))?;
-                        let mut args_inner = match last_segment {
-                            Some(it) => it.as_ref().clone(),
-                            None => GenericArgs::empty(),
-                        };
-                        args_inner.has_self_type = true;
-                        args_inner.args.insert(0, GenericArg::Type(self_type));
-                        *last_segment = Some(Interned::new(args_inner));
+                        let last_segment = generic_args.get_mut(segments.len() - num_segments)?;
+                        *last_segment = Some(Interned::new(match last_segment.take() {
+                            Some(it) => GenericArgs {
+                                args: iter::once(self_type)
+                                    .chain(it.args.iter().cloned())
+                                    .collect(),
+
+                                has_self_type: true,
+                                bindings: it.bindings.clone(),
+                                desugared_from_fn: it.desugared_from_fn,
+                            },
+                            None => GenericArgs {
+                                args: Box::new([self_type]),
+                                has_self_type: true,
+                                ..GenericArgs::empty()
+                            },
+                        }));
                     }
                 }
             }
@@ -114,7 +134,10 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path
         };
     }
     segments.reverse();
-    generic_args.reverse();
+    if !generic_args.is_empty() {
+        generic_args.resize(segments.len(), None);
+        generic_args.reverse();
+    }
 
     if segments.is_empty() && kind == PathKind::Plain && type_anchor.is_none() {
         // plain empty paths don't exist, this means we got a single `self` segment as our path
@@ -134,7 +157,11 @@ pub(super) fn lower_path(mut path: ast::Path, ctx: &LowerCtx<'_>) -> Option<Path
     }
 
     let mod_path = Interned::new(ModPath::from_segments(kind, segments));
-    return Some(Path { type_anchor, mod_path, generic_args: generic_args.into() });
+    return Some(Path {
+        type_anchor,
+        mod_path,
+        generic_args: if generic_args.is_empty() { None } else { Some(generic_args.into()) },
+    });
 
     fn qualifier(path: &ast::Path) -> Option<ast::Path> {
         if let Some(q) = path.qualifier() {
@@ -173,7 +200,7 @@ pub(super) fn lower_generic_args(
                             .map(|it| Interned::new(TypeBound::from_ast(lower_ctx, it)))
                             .collect()
                     } else {
-                        Vec::new()
+                        Box::default()
                     };
                     bindings.push(AssociatedTypeBinding { name, args, type_ref, bounds });
                 }
@@ -194,7 +221,12 @@ pub(super) fn lower_generic_args(
     if args.is_empty() && bindings.is_empty() {
         return None;
     }
-    Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: false })
+    Some(GenericArgs {
+        args: args.into_boxed_slice(),
+        has_self_type: false,
+        bindings: bindings.into_boxed_slice(),
+        desugared_from_fn: false,
+    })
 }
 
 /// Collect `GenericArgs` from the parts of a fn-like path, i.e. `Fn(X, Y)
@@ -204,33 +236,30 @@ fn lower_generic_args_from_fn_path(
     params: Option<ast::ParamList>,
     ret_type: Option<ast::RetType>,
 ) -> Option<GenericArgs> {
-    let mut args = Vec::new();
-    let mut bindings = Vec::new();
     let params = params?;
     let mut param_types = Vec::new();
     for param in params.params() {
         let type_ref = TypeRef::from_ast_opt(ctx, param.ty());
         param_types.push(type_ref);
     }
-    let arg = GenericArg::Type(TypeRef::Tuple(param_types));
-    args.push(arg);
-    if let Some(ret_type) = ret_type {
+    let args = Box::new([GenericArg::Type(TypeRef::Tuple(param_types))]);
+    let bindings = if let Some(ret_type) = ret_type {
         let type_ref = TypeRef::from_ast_opt(ctx, ret_type.ty());
-        bindings.push(AssociatedTypeBinding {
+        Box::new([AssociatedTypeBinding {
             name: name![Output],
             args: None,
             type_ref: Some(type_ref),
-            bounds: Vec::new(),
-        });
+            bounds: Box::default(),
+        }])
     } else {
         // -> ()
         let type_ref = TypeRef::Tuple(Vec::new());
-        bindings.push(AssociatedTypeBinding {
+        Box::new([AssociatedTypeBinding {
             name: name![Output],
             args: None,
             type_ref: Some(type_ref),
-            bounds: Vec::new(),
-        });
-    }
+            bounds: Box::default(),
+        }])
+    };
     Some(GenericArgs { args, has_self_type: false, bindings, desugared_from_fn: true })
 }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs b/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs
index befd0c5ff..2d45c8c8d 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/pretty.rs
@@ -3,10 +3,10 @@
 use std::fmt::{self, Write};
 
 use hir_expand::mod_path::PathKind;
+use intern::Interned;
 use itertools::Itertools;
 
 use crate::{
-    intern::Interned,
     path::{GenericArg, GenericArgs, Path},
     type_ref::{Mutability, TraitBoundModifier, TypeBound, TypeRef},
 };
@@ -71,7 +71,7 @@ pub(crate) fn print_generic_args(generics: &GenericArgs, buf: &mut dyn Write) ->
         first = false;
         print_generic_arg(arg, buf)?;
     }
-    for binding in &generics.bindings {
+    for binding in generics.bindings.iter() {
         if !first {
             write!(buf, ", ")?;
         }
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/resolver.rs b/src/tools/rust-analyzer/crates/hir-def/src/resolver.rs
index 1ef7f9577..86958e3da 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/resolver.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/resolver.rs
@@ -4,6 +4,7 @@ use std::{hash::BuildHasherDefault, sync::Arc};
 use base_db::CrateId;
 use hir_expand::name::{name, Name};
 use indexmap::IndexMap;
+use intern::Interned;
 use rustc_hash::FxHashSet;
 use smallvec::{smallvec, SmallVec};
 
@@ -13,7 +14,6 @@ use crate::{
     db::DefDatabase,
     expr::{ExprId, LabelId, PatId},
     generics::{GenericParams, TypeOrConstParamData},
-    intern::Interned,
     item_scope::{BuiltinShadowMode, BUILTIN_SCOPE},
     nameres::DefMap,
     path::{ModPath, PathKind},
diff --git a/src/tools/rust-analyzer/crates/hir-def/src/type_ref.rs b/src/tools/rust-analyzer/crates/hir-def/src/type_ref.rs
index f8bb78ddc..9652b01b9 100644
--- a/src/tools/rust-analyzer/crates/hir-def/src/type_ref.rs
+++ b/src/tools/rust-analyzer/crates/hir-def/src/type_ref.rs
@@ -7,13 +7,13 @@ use hir_expand::{
     name::{AsName, Name},
     AstId,
 };
+use intern::Interned;
 use syntax::ast::{self, HasName};
 
 use crate::{
     body::LowerCtx,
     builtin_type::{BuiltinInt, BuiltinType, BuiltinUint},
     expr::Literal,
-    intern::Interned,
     path::Path,
 };
 
@@ -240,7 +240,7 @@ impl TypeRef {
                 TypeRef::DynTrait(type_bounds_from_ast(ctx, inner.type_bound_list()))
             }
             ast::Type::MacroType(mt) => match mt.macro_call() {
-                Some(mc) => ctx.ast_id(ctx.db, &mc).map(TypeRef::Macro).unwrap_or(TypeRef::Error),
+                Some(mc) => ctx.ast_id(&mc).map(TypeRef::Macro).unwrap_or(TypeRef::Error),
                 None => TypeRef::Error,
             },
         }
@@ -292,7 +292,7 @@ impl TypeRef {
             }
             for segment in path.segments().iter() {
                 if let Some(args_and_bindings) = segment.args_and_bindings {
-                    for arg in &args_and_bindings.args {
+                    for arg in args_and_bindings.args.iter() {
                         match arg {
                             crate::path::GenericArg::Type(type_ref) => {
                                 go(type_ref, f);
@@ -301,11 +301,11 @@ impl TypeRef {
                             | crate::path::GenericArg::Lifetime(_) => {}
                         }
                     }
-                    for binding in &args_and_bindings.bindings {
+                    for binding in args_and_bindings.bindings.iter() {
                         if let Some(type_ref) = &binding.type_ref {
                             go(type_ref, f);
                         }
-                        for bound in &binding.bounds {
+                        for bound in binding.bounds.iter() {
                             match bound.as_ref() {
                                 TypeBound::Path(path, _) | TypeBound::ForLifetime(_, path) => {
                                     go_path(path, f)