13 files changed, 417 insertions, 171 deletions

diff --git a/crates/hir_def/src/adt.rs b/crates/hir_def/src/adt.rs
index eafa3abb6..236d6f1b7 100644
--- a/crates/hir_def/src/adt.rs
+++ b/crates/hir_def/src/adt.rs
@@ -3,6 +3,7 @@
 use std::sync::Arc;
 
 use arena::{map::ArenaMap, Arena};
+use base_db::CrateId;
 use either::Either;
 use hir_expand::{
     name::{AsName, Name},
@@ -66,8 +67,13 @@ pub enum ReprKind {
     Other,
 }
 
-fn repr_from_value(item_tree: &ItemTree, of: AttrOwner) -> Option<ReprKind> {
-    item_tree.attrs(of).by_key("repr").tt_values().find_map(parse_repr_tt)
+fn repr_from_value(
+    db: &dyn DefDatabase,
+    krate: CrateId,
+    item_tree: &ItemTree,
+    of: AttrOwner,
+) -> Option<ReprKind> {
+    item_tree.attrs(db, krate, of).by_key("repr").tt_values().find_map(parse_repr_tt)
 }
 
 fn parse_repr_tt(tt: &Subtree) -> Option<ReprKind> {
@@ -86,12 +92,13 @@ fn parse_repr_tt(tt: &Subtree) -> Option<ReprKind> {
 impl StructData {
     pub(crate) fn struct_data_query(db: &dyn DefDatabase, id: StructId) -> Arc<StructData> {
         let loc = id.lookup(db);
+        let krate = loc.container.module(db).krate;
         let item_tree = db.item_tree(loc.id.file_id);
-        let repr = repr_from_value(&item_tree, ModItem::from(loc.id.value).into());
+        let repr = repr_from_value(db, krate, &item_tree, ModItem::from(loc.id.value).into());
         let cfg_options = db.crate_graph()[loc.container.module(db).krate].cfg_options.clone();
 
         let strukt = &item_tree[loc.id.value];
-        let variant_data = lower_fields(&item_tree, &cfg_options, &strukt.fields, None);
+        let variant_data = lower_fields(db, krate, &item_tree, &cfg_options, &strukt.fields, None);
         Arc::new(StructData {
             name: strukt.name.clone(),
             variant_data: Arc::new(variant_data),
@@ -100,12 +107,13 @@ impl StructData {
     }
     pub(crate) fn union_data_query(db: &dyn DefDatabase, id: UnionId) -> Arc<StructData> {
         let loc = id.lookup(db);
+        let krate = loc.container.module(db).krate;
         let item_tree = db.item_tree(loc.id.file_id);
-        let repr = repr_from_value(&item_tree, ModItem::from(loc.id.value).into());
+        let repr = repr_from_value(db, krate, &item_tree, ModItem::from(loc.id.value).into());
         let cfg_options = db.crate_graph()[loc.container.module(db).krate].cfg_options.clone();
 
         let union = &item_tree[loc.id.value];
-        let variant_data = lower_fields(&item_tree, &cfg_options, &union.fields, None);
+        let variant_data = lower_fields(db, krate, &item_tree, &cfg_options, &union.fields, None);
 
         Arc::new(StructData {
             name: union.name.clone(),
@@ -118,16 +126,23 @@ impl StructData {
 impl EnumData {
     pub(crate) fn enum_data_query(db: &dyn DefDatabase, e: EnumId) -> Arc<EnumData> {
         let loc = e.lookup(db);
+        let krate = loc.container.module(db).krate;
         let item_tree = db.item_tree(loc.id.file_id);
-        let cfg_options = db.crate_graph()[loc.container.module(db).krate].cfg_options.clone();
+        let cfg_options = db.crate_graph()[krate].cfg_options.clone();
 
         let enum_ = &item_tree[loc.id.value];
         let mut variants = Arena::new();
         for var_id in enum_.variants.clone() {
-            if item_tree.attrs(var_id.into()).is_cfg_enabled(&cfg_options) {
+            if item_tree.attrs(db, krate, var_id.into()).is_cfg_enabled(&cfg_options) {
                 let var = &item_tree[var_id];
-                let var_data =
-                    lower_fields(&item_tree, &cfg_options, &var.fields, Some(enum_.visibility));
+                let var_data = lower_fields(
+                    db,
+                    krate,
+                    &item_tree,
+                    &cfg_options,
+                    &var.fields,
+                    Some(enum_.visibility),
+                );
 
                 variants.alloc(EnumVariantData {
                     name: var.name.clone(),
@@ -170,7 +185,7 @@ fn lower_enum(
         .variant_list()
         .into_iter()
         .flat_map(|it| it.variants())
-        .filter(|var| expander.is_cfg_enabled(var));
+        .filter(|var| expander.is_cfg_enabled(db, var));
     for var in variants {
         trace.alloc(
             || var.clone(),
@@ -262,7 +277,7 @@ fn lower_struct(
     match &ast.value {
         ast::StructKind::Tuple(fl) => {
             for (i, fd) in fl.fields().enumerate() {
-                if !expander.is_cfg_enabled(&fd) {
+                if !expander.is_cfg_enabled(db, &fd) {
                     continue;
                 }
 
@@ -279,7 +294,7 @@ fn lower_struct(
         }
         ast::StructKind::Record(fl) => {
             for fd in fl.fields() {
-                if !expander.is_cfg_enabled(&fd) {
+                if !expander.is_cfg_enabled(db, &fd) {
                     continue;
                 }
 
@@ -299,6 +314,8 @@ fn lower_struct(
 }
 
 fn lower_fields(
+    db: &dyn DefDatabase,
+    krate: CrateId,
     item_tree: &ItemTree,
     cfg_options: &CfgOptions,
     fields: &Fields,
@@ -308,7 +325,7 @@ fn lower_fields(
         Fields::Record(flds) => {
             let mut arena = Arena::new();
             for field_id in flds.clone() {
-                if item_tree.attrs(field_id.into()).is_cfg_enabled(cfg_options) {
+                if item_tree.attrs(db, krate, field_id.into()).is_cfg_enabled(cfg_options) {
                     arena.alloc(lower_field(item_tree, &item_tree[field_id], override_visibility));
                 }
             }
@@ -317,7 +334,7 @@ fn lower_fields(
         Fields::Tuple(flds) => {
             let mut arena = Arena::new();
             for field_id in flds.clone() {
-                if item_tree.attrs(field_id.into()).is_cfg_enabled(cfg_options) {
+                if item_tree.attrs(db, krate, field_id.into()).is_cfg_enabled(cfg_options) {
                     arena.alloc(lower_field(item_tree, &item_tree[field_id], override_visibility));
                 }
             }
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index c64b78445..042e119b1 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -2,22 +2,24 @@
 
 use std::{ops, sync::Arc};
 
+use base_db::CrateId;
 use cfg::{CfgExpr, CfgOptions};
 use either::Either;
-use hir_expand::{hygiene::Hygiene, AstId, InFile};
+use hir_expand::{hygiene::Hygiene, name::AsName, AstId, InFile};
 use itertools::Itertools;
 use mbe::ast_to_token_tree;
 use syntax::{
     ast::{self, AstNode, AttrsOwner},
     match_ast, AstToken, SmolStr, SyntaxNode,
 };
+use test_utils::mark;
 use tt::Subtree;
 
 use crate::{
     db::DefDatabase,
     item_tree::{ItemTreeId, ItemTreeNode},
     nameres::ModuleSource,
-    path::ModPath,
+    path::{ModPath, PathKind},
     src::HasChildSource,
     AdtId, AttrDefId, Lookup,
 };
@@ -38,12 +40,16 @@ impl From<Documentation> for String {
     }
 }
 
+/// Syntactical attributes, without filtering of `cfg_attr`s.
 #[derive(Default, Debug, Clone, PartialEq, Eq)]
-pub struct Attrs {
+pub(crate) struct RawAttrs {
     entries: Option<Arc<[Attr]>>,
 }
 
-impl ops::Deref for Attrs {
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct Attrs(RawAttrs);
+
+impl ops::Deref for RawAttrs {
     type Target = [Attr];
 
     fn deref(&self) -> &[Attr] {
@@ -54,19 +60,147 @@ impl ops::Deref for Attrs {
     }
 }
 
+impl ops::Deref for Attrs {
+    type Target = [Attr];
+
+    fn deref(&self) -> &[Attr] {
+        match &self.0.entries {
+            Some(it) => &*it,
+            None => &[],
+        }
+    }
+}
+
+impl RawAttrs {
+    pub(crate) const EMPTY: Self = Self { entries: None };
+
+    pub(crate) fn new(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Self {
+        let attrs: Vec<_> = collect_attrs(owner).collect();
+        let entries = if attrs.is_empty() {
+            // Avoid heap allocation
+            None
+        } else {
+            Some(
+                attrs
+                    .into_iter()
+                    .enumerate()
+                    .flat_map(|(i, attr)| match attr {
+                        Either::Left(attr) => Attr::from_src(attr, hygiene).map(|attr| (i, attr)),
+                        Either::Right(comment) => comment.doc_comment().map(|doc| {
+                            (
+                                i,
+                                Attr {
+                                    index: 0,
+                                    input: Some(AttrInput::Literal(SmolStr::new(doc))),
+                                    path: ModPath::from(hir_expand::name!(doc)),
+                                },
+                            )
+                        }),
+                    })
+                    .map(|(i, attr)| Attr { index: i as u32, ..attr })
+                    .collect(),
+            )
+        };
+        Self { entries }
+    }
+
+    fn from_attrs_owner(db: &dyn DefDatabase, owner: InFile<&dyn AttrsOwner>) -> Self {
+        let hygiene = Hygiene::new(db.upcast(), owner.file_id);
+        Self::new(owner.value, &hygiene)
+    }
+
+    pub(crate) fn merge(&self, other: Self) -> Self {
+        match (&self.entries, &other.entries) {
+            (None, None) => Self::EMPTY,
+            (Some(entries), None) | (None, Some(entries)) => {
+                Self { entries: Some(entries.clone()) }
+            }
+            (Some(a), Some(b)) => {
+                Self { entries: Some(a.iter().chain(b.iter()).cloned().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()
+            .filter_map(|attr| {
+                let attr = attr.clone();
+                let is_cfg_attr =
+                    attr.path.as_ident().map_or(false, |name| *name == hir_expand::name![cfg_attr]);
+                if !is_cfg_attr {
+                    return Some(attr);
+                }
+
+                let subtree = match &attr.input {
+                    Some(AttrInput::TokenTree(it)) => it,
+                    _ => return Some(attr),
+                };
+
+                // Input subtree is: `(cfg, attr)`
+                // Split it up into a `cfg` and an `attr` subtree.
+                // FIXME: There should be a common API for this.
+                let mut saw_comma = false;
+                let (mut cfg, attr): (Vec<_>, Vec<_>) =
+                    subtree.clone().token_trees.into_iter().partition(|tree| {
+                        if saw_comma {
+                            return false;
+                        }
+
+                        match tree {
+                            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                                saw_comma = true;
+                            }
+                            _ => {}
+                        }
+
+                        true
+                    });
+                cfg.pop(); // `,` ends up in here
+
+                let attr = Subtree { delimiter: None, token_trees: attr };
+                let cfg = Subtree { delimiter: subtree.delimiter, token_trees: cfg };
+                let cfg = CfgExpr::parse(&cfg);
+
+                let cfg_options = &crate_graph[krate].cfg_options;
+                if cfg_options.check(&cfg) == Some(false) {
+                    None
+                } else {
+                    mark::hit!(cfg_attr_active);
+
+                    let attr = ast::Attr::parse(&format!("#[{}]", attr)).ok()?;
+                    let hygiene = Hygiene::new_unhygienic(); // FIXME
+                    Attr::from_src(attr, &hygiene)
+                }
+            })
+            .collect();
+
+        Attrs(RawAttrs { entries: Some(new_attrs) })
+    }
+}
+
 impl Attrs {
-    pub const EMPTY: Attrs = Attrs { entries: None };
+    pub const EMPTY: Self = Self(RawAttrs::EMPTY);
 
     pub(crate) fn attrs_query(db: &dyn DefDatabase, def: AttrDefId) -> Attrs {
-        match def {
+        let raw_attrs = match def {
             AttrDefId::ModuleId(module) => {
                 let def_map = db.crate_def_map(module.krate);
                 let mod_data = &def_map[module.local_id];
                 match mod_data.declaration_source(db) {
                     Some(it) => {
-                        Attrs::from_attrs_owner(db, it.as_ref().map(|it| it as &dyn AttrsOwner))
+                        RawAttrs::from_attrs_owner(db, it.as_ref().map(|it| it as &dyn AttrsOwner))
                     }
-                    None => Attrs::from_attrs_owner(
+                    None => RawAttrs::from_attrs_owner(
                         db,
                         mod_data.definition_source(db).as_ref().map(|src| match src {
                             ModuleSource::SourceFile(file) => file as &dyn AttrsOwner,
@@ -78,14 +212,14 @@ impl Attrs {
             AttrDefId::FieldId(it) => {
                 let src = it.parent.child_source(db);
                 match &src.value[it.local_id] {
-                    Either::Left(_tuple) => Attrs::default(),
-                    Either::Right(record) => Attrs::from_attrs_owner(db, src.with_value(record)),
+                    Either::Left(_tuple) => RawAttrs::default(),
+                    Either::Right(record) => RawAttrs::from_attrs_owner(db, src.with_value(record)),
                 }
             }
             AttrDefId::EnumVariantId(var_id) => {
                 let src = var_id.parent.child_source(db);
                 let src = src.as_ref().map(|it| &it[var_id.local_id]);
-                Attrs::from_attrs_owner(db, src.map(|it| it as &dyn AttrsOwner))
+                RawAttrs::from_attrs_owner(db, src.map(|it| it as &dyn AttrsOwner))
             }
             AttrDefId::AdtId(it) => match it {
                 AdtId::StructId(it) => attrs_from_item_tree(it.lookup(db).id, db),
@@ -101,55 +235,9 @@ impl Attrs {
             AttrDefId::StaticId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::FunctionId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::TypeAliasId(it) => attrs_from_item_tree(it.lookup(db).id, db),
-        }
-    }
-
-    pub fn from_attrs_owner(db: &dyn DefDatabase, owner: InFile<&dyn AttrsOwner>) -> Attrs {
-        let hygiene = Hygiene::new(db.upcast(), owner.file_id);
-        Attrs::new(owner.value, &hygiene)
-    }
-
-    pub(crate) fn new(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Attrs {
-        let (inner_attrs, inner_docs) = inner_attributes(owner.syntax())
-            .map_or((None, None), |(attrs, docs)| ((Some(attrs), Some(docs))));
-
-        let outer_attrs = owner.attrs().filter(|attr| attr.excl_token().is_none());
-        let attrs = outer_attrs
-            .chain(inner_attrs.into_iter().flatten())
-            .map(|attr| (attr.syntax().text_range().start(), Attr::from_src(attr, hygiene)));
-
-        let outer_docs =
-            ast::CommentIter::from_syntax_node(owner.syntax()).filter(ast::Comment::is_outer);
-        let docs = outer_docs.chain(inner_docs.into_iter().flatten()).map(|docs_text| {
-            (
-                docs_text.syntax().text_range().start(),
-                docs_text.doc_comment().map(|doc| Attr {
-                    input: Some(AttrInput::Literal(SmolStr::new(doc))),
-                    path: ModPath::from(hir_expand::name!(doc)),
-                }),
-            )
-        });
-        // sort here by syntax node offset because the source can have doc attributes and doc strings be interleaved
-        let attrs: Vec<_> = docs.chain(attrs).sorted_by_key(|&(offset, _)| offset).collect();
-        let entries = if attrs.is_empty() {
-            // Avoid heap allocation
-            None
-        } else {
-            Some(attrs.into_iter().flat_map(|(_, attr)| attr).collect())
         };
-        Attrs { entries }
-    }
 
-    pub fn merge(&self, other: Attrs) -> Attrs {
-        match (&self.entries, &other.entries) {
-            (None, None) => Attrs { entries: None },
-            (Some(entries), None) | (None, Some(entries)) => {
-                Attrs { entries: Some(entries.clone()) }
-            }
-            (Some(a), Some(b)) => {
-                Attrs { entries: Some(a.iter().chain(b.iter()).cloned().collect()) }
-            }
-        }
+        raw_attrs.filter(db, def.krate(db))
     }
 
     pub fn by_key(&self, key: &'static str) -> AttrQuery<'_> {
@@ -157,7 +245,6 @@ impl Attrs {
     }
 
     pub fn cfg(&self) -> Option<CfgExpr> {
-        // FIXME: handle cfg_attr :-)
         let mut cfgs = self.by_key("cfg").tt_values().map(CfgExpr::parse).collect::<Vec<_>>();
         match cfgs.len() {
             0 => None,
@@ -228,6 +315,7 @@ fn inner_attributes(
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Attr {
+    index: u32,
     pub(crate) path: ModPath,
     pub(crate) input: Option<AttrInput>,
 }
@@ -254,7 +342,59 @@ impl Attr {
         } else {
             None
         };
-        Some(Attr { path, input })
+        Some(Attr { index: 0, path, input })
+    }
+
+    /// Maps this lowered `Attr` back to its original syntax node.
+    ///
+    /// `owner` must be the original owner of the attribute.
+    ///
+    /// Note that the returned syntax node might be a `#[cfg_attr]`, or a doc comment, instead of
+    /// the attribute represented by `Attr`.
+    pub fn to_src(&self, owner: &dyn AttrsOwner) -> Either<ast::Attr, ast::Comment> {
+        collect_attrs(owner).nth(self.index as usize).unwrap_or_else(|| {
+            panic!("cannot find `Attr` at index {} in {}", self.index, owner.syntax())
+        })
+    }
+
+    /// Parses this attribute as a `#[derive]`, returns an iterator that yields all contained paths
+    /// to derive macros.
+    ///
+    /// Returns `None` when the attribute is not a well-formed `#[derive]` attribute.
+    pub(crate) fn parse_derive(&self) -> Option<impl Iterator<Item = ModPath>> {
+        if self.path.as_ident() != Some(&hir_expand::name![derive]) {
+            return None;
+        }
+
+        match &self.input {
+            Some(AttrInput::TokenTree(args)) => {
+                let mut counter = 0;
+                let paths = args
+                    .token_trees
+                    .iter()
+                    .group_by(move |tt| {
+                        match tt {
+                            tt::TokenTree::Leaf(tt::Leaf::Punct(p)) if p.char == ',' => {
+                                counter += 1;
+                            }
+                            _ => {}
+                        }
+                        counter
+                    })
+                    .into_iter()
+                    .map(|(_, tts)| {
+                        let segments = tts.filter_map(|tt| match tt {
+                            tt::TokenTree::Leaf(tt::Leaf::Ident(id)) => Some(id.as_name()),
+                            _ => None,
+                        });
+                        ModPath::from_segments(PathKind::Plain, segments)
+                    })
+                    .collect::<Vec<_>>();
+
+                Some(paths.into_iter())
+            }
+            _ => None,
+        }
     }
 }
 
@@ -283,7 +423,7 @@ impl<'a> AttrQuery<'a> {
         self.attrs().next().is_some()
     }
 
-    fn attrs(self) -> impl Iterator<Item = &'a Attr> {
+    pub(crate) fn attrs(self) -> impl Iterator<Item = &'a Attr> {
         let key = self.key;
         self.attrs
             .iter()
@@ -291,16 +431,36 @@ impl<'a> AttrQuery<'a> {
     }
 }
 
-fn attrs_from_ast<N>(src: AstId<N>, db: &dyn DefDatabase) -> Attrs
+fn attrs_from_ast<N>(src: AstId<N>, db: &dyn DefDatabase) -> RawAttrs
 where
     N: ast::AttrsOwner,
 {
     let src = InFile::new(src.file_id, src.to_node(db.upcast()));
-    Attrs::from_attrs_owner(db, src.as_ref().map(|it| it as &dyn AttrsOwner))
+    RawAttrs::from_attrs_owner(db, src.as_ref().map(|it| it as &dyn AttrsOwner))
 }
 
-fn attrs_from_item_tree<N: ItemTreeNode>(id: ItemTreeId<N>, db: &dyn DefDatabase) -> Attrs {
+fn attrs_from_item_tree<N: ItemTreeNode>(id: ItemTreeId<N>, db: &dyn DefDatabase) -> RawAttrs {
     let tree = db.item_tree(id.file_id);
     let mod_item = N::id_to_mod_item(id.value);
-    tree.attrs(mod_item.into()).clone()
+    tree.raw_attrs(mod_item.into()).clone()
+}
+
+fn collect_attrs(owner: &dyn AttrsOwner) -> impl Iterator<Item = Either<ast::Attr, ast::Comment>> {
+    let (inner_attrs, inner_docs) = inner_attributes(owner.syntax())
+        .map_or((None, None), |(attrs, docs)| ((Some(attrs), Some(docs))));
+
+    let outer_attrs = owner.attrs().filter(|attr| attr.excl_token().is_none());
+    let attrs = outer_attrs
+        .chain(inner_attrs.into_iter().flatten())
+        .map(|attr| (attr.syntax().text_range().start(), Either::Left(attr)));
+
+    let outer_docs =
+        ast::CommentIter::from_syntax_node(owner.syntax()).filter(ast::Comment::is_outer);
+    let docs = outer_docs
+        .chain(inner_docs.into_iter().flatten())
+        .map(|docs_text| (docs_text.syntax().text_range().start(), Either::Right(docs_text)));
+    // sort here by syntax node offset because the source can have doc attributes and doc strings be interleaved
+    let attrs: Vec<_> = docs.chain(attrs).sorted_by_key(|&(offset, _)| offset).collect();
+
+    attrs.into_iter().map(|(_, attr)| attr)
 }
diff --git a/crates/hir_def/src/body.rs b/crates/hir_def/src/body.rs
index c5d6f5fb0..998b82601 100644
--- a/crates/hir_def/src/body.rs
+++ b/crates/hir_def/src/body.rs
@@ -24,7 +24,7 @@ use test_utils::mark;
 pub(crate) use lower::LowerCtx;
 
 use crate::{
-    attr::Attrs,
+    attr::{Attrs, RawAttrs},
     db::DefDatabase,
     expr::{Expr, ExprId, Pat, PatId},
     item_scope::BuiltinShadowMode,
@@ -40,6 +40,7 @@ use crate::{
 pub(crate) struct CfgExpander {
     cfg_options: CfgOptions,
     hygiene: Hygiene,
+    krate: CrateId,
 }
 
 pub(crate) struct Expander {
@@ -65,15 +66,15 @@ impl CfgExpander {
     ) -> CfgExpander {
         let hygiene = Hygiene::new(db.upcast(), current_file_id);
         let cfg_options = db.crate_graph()[krate].cfg_options.clone();
-        CfgExpander { cfg_options, hygiene }
+        CfgExpander { cfg_options, hygiene, krate }
     }
 
-    pub(crate) fn parse_attrs(&self, owner: &dyn ast::AttrsOwner) -> Attrs {
-        Attrs::new(owner, &self.hygiene)
+    pub(crate) fn parse_attrs(&self, db: &dyn DefDatabase, owner: &dyn ast::AttrsOwner) -> Attrs {
+        RawAttrs::new(owner, &self.hygiene).filter(db, self.krate)
     }
 
-    pub(crate) fn is_cfg_enabled(&self, owner: &dyn ast::AttrsOwner) -> bool {
-        let attrs = self.parse_attrs(owner);
+    pub(crate) fn is_cfg_enabled(&self, db: &dyn DefDatabase, owner: &dyn ast::AttrsOwner) -> bool {
+        let attrs = self.parse_attrs(db, owner);
         attrs.is_cfg_enabled(&self.cfg_options)
     }
 }
@@ -189,8 +190,8 @@ impl Expander {
         InFile { file_id: self.current_file_id, value }
     }
 
-    pub(crate) fn parse_attrs(&self, owner: &dyn ast::AttrsOwner) -> Attrs {
-        self.cfg_expander.parse_attrs(owner)
+    pub(crate) fn parse_attrs(&self, db: &dyn DefDatabase, owner: &dyn ast::AttrsOwner) -> Attrs {
+        self.cfg_expander.parse_attrs(db, owner)
     }
 
     pub(crate) fn cfg_options(&self) -> &CfgOptions {
diff --git a/crates/hir_def/src/body/lower.rs b/crates/hir_def/src/body/lower.rs
index 3b3d74987..0f404be1b 100644
--- a/crates/hir_def/src/body/lower.rs
+++ b/crates/hir_def/src/body/lower.rs
@@ -963,7 +963,7 @@ impl ExprCollector<'_> {
     /// Returns `None` (and emits diagnostics) when `owner` if `#[cfg]`d out, and `Some(())` when
     /// not.
     fn check_cfg(&mut self, owner: &dyn ast::AttrsOwner) -> Option<()> {
-        match self.expander.parse_attrs(owner).cfg() {
+        match self.expander.parse_attrs(self.db, owner).cfg() {
             Some(cfg) => {
                 if self.expander.cfg_options().check(&cfg) != Some(false) {
                     return Some(());
diff --git a/crates/hir_def/src/data.rs b/crates/hir_def/src/data.rs
index dd3a906af..e7b7724f7 100644
--- a/crates/hir_def/src/data.rs
+++ b/crates/hir_def/src/data.rs
@@ -35,6 +35,7 @@ pub struct FunctionData {
 impl FunctionData {
     pub(crate) fn fn_data_query(db: &dyn DefDatabase, func: FunctionId) -> Arc<FunctionData> {
         let loc = func.lookup(db);
+        let krate = loc.container.module(db).krate;
         let item_tree = db.item_tree(loc.id.file_id);
         let func = &item_tree[loc.id.value];
 
@@ -42,7 +43,7 @@ impl FunctionData {
             name: func.name.clone(),
             params: func.params.to_vec(),
             ret_type: func.ret_type.clone(),
-            attrs: item_tree.attrs(ModItem::from(loc.id.value).into()).clone(),
+            attrs: item_tree.attrs(db, krate, ModItem::from(loc.id.value).into()).clone(),
             has_self_param: func.has_self_param,
             has_body: func.has_body,
             is_unsafe: func.is_unsafe,
@@ -233,7 +234,7 @@ fn collect_items(
         match item {
             AssocItem::Function(id) => {
                 let item = &item_tree[id];
-                let attrs = item_tree.attrs(ModItem::from(id).into());
+                let attrs = item_tree.attrs(db, module.krate, ModItem::from(id).into());
                 if !attrs.is_cfg_enabled(&cfg_options) {
                     continue;
                 }
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index b8e09e3af..100dbf5d6 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -12,7 +12,8 @@ use std::{
 };
 
 use arena::{Arena, Idx, RawId};
-use ast::{AstNode, AttrsOwner, NameOwner, StructKind};
+use ast::{AstNode, NameOwner, StructKind};
+use base_db::CrateId;
 use either::Either;
 use hir_expand::{
     ast_id_map::FileAstId,
@@ -26,7 +27,7 @@ use syntax::{ast, match_ast};
 use test_utils::mark;
 
 use crate::{
-    attr::Attrs,
+    attr::{Attrs, RawAttrs},
     db::DefDatabase,
     generics::GenericParams,
     path::{path, AssociatedTypeBinding, GenericArgs, ImportAlias, ModPath, Path, PathKind},
@@ -67,7 +68,7 @@ impl GenericParamsId {
 #[derive(Debug, Eq, PartialEq)]
 pub struct ItemTree {
     top_level: SmallVec<[ModItem; 1]>,
-    attrs: FxHashMap<AttrOwner, Attrs>,
+    attrs: FxHashMap<AttrOwner, RawAttrs>,
     inner_items: FxHashMap<FileAstId<ast::Item>, SmallVec<[ModItem; 1]>>,
 
     data: Option<Box<ItemTreeData>>,
@@ -88,7 +89,7 @@ impl ItemTree {
         let mut item_tree = match_ast! {
             match syntax {
                 ast::SourceFile(file) => {
-                    top_attrs = Some(Attrs::new(&file, &hygiene));
+                    top_attrs = Some(RawAttrs::new(&file, &hygiene));
                     ctx.lower_module_items(&file)
                 },
                 ast::MacroItems(items) => {
@@ -180,12 +181,16 @@ impl ItemTree {
     }
 
     /// Returns the inner attributes of the source file.
-    pub fn top_level_attrs(&self) -> &Attrs {
-        self.attrs.get(&AttrOwner::TopLevel).unwrap_or(&Attrs::EMPTY)
+    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)
     }
 
-    pub fn attrs(&self, of: AttrOwner) -> &Attrs {
-        self.attrs.get(&of).unwrap_or(&Attrs::EMPTY)
+    pub(crate) fn raw_attrs(&self, of: AttrOwner) -> &RawAttrs {
+        self.attrs.get(&of).unwrap_or(&RawAttrs::EMPTY)
+    }
+
+    pub fn attrs(&self, db: &dyn DefDatabase, krate: CrateId, of: AttrOwner) -> Attrs {
+        self.raw_attrs(of).clone().filter(db, krate)
     }
 
     /// Returns the lowered inner items that `ast` corresponds to.
@@ -490,7 +495,6 @@ pub struct Import {
     pub alias: Option<ImportAlias>,
     pub visibility: RawVisibilityId,
     pub is_glob: bool,
-    pub is_prelude: bool,
     /// AST ID of the `use` or `extern crate` item this import was derived from. Note that many
     /// `Import`s can map to the same `use` item.
     pub ast_id: FileAstId<ast::Use>,
@@ -506,8 +510,6 @@ pub struct ExternCrate {
     pub name: Name,
     pub alias: Option<ImportAlias>,
     pub visibility: RawVisibilityId,
-    /// Whether this is a `#[macro_use] extern crate ...`.
-    pub is_macro_use: bool,
     pub ast_id: FileAstId<ast::ExternCrate>,
 }
 
diff --git a/crates/hir_def/src/item_tree/lower.rs b/crates/hir_def/src/item_tree/lower.rs
index 7de385ee8..3b206ef85 100644
--- a/crates/hir_def/src/item_tree/lower.rs
+++ b/crates/hir_def/src/item_tree/lower.rs
@@ -10,7 +10,6 @@ use syntax::{
 };
 
 use crate::{
-    attr::Attrs,
     generics::{GenericParams, TypeParamData, TypeParamProvenance},
     type_ref::LifetimeRef,
 };
@@ -105,7 +104,7 @@ impl Ctx {
             | ast::Item::MacroDef(_) => {}
         };
 
-        let attrs = Attrs::new(item, &self.hygiene);
+        let attrs = RawAttrs::new(item, &self.hygiene);
         let items = match item {
             ast::Item::Struct(ast) => self.lower_struct(ast).map(Into::into),
             ast::Item::Union(ast) => self.lower_union(ast).map(Into::into),
@@ -138,7 +137,7 @@ impl Ctx {
         items
     }
 
-    fn add_attrs(&mut self, item: AttrOwner, attrs: Attrs) {
+    fn add_attrs(&mut self, item: AttrOwner, attrs: RawAttrs) {
         match self.tree.attrs.entry(item) {
             Entry::Occupied(mut entry) => {
                 *entry.get_mut() = entry.get().merge(attrs);
@@ -205,7 +204,7 @@ impl Ctx {
         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(), Attrs::new(&field, &self.hygiene));
+                self.add_attrs(idx.into(), RawAttrs::new(&field, &self.hygiene));
             }
         }
         let end = self.next_field_idx();
@@ -225,7 +224,7 @@ impl Ctx {
         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(), Attrs::new(&field, &self.hygiene));
+            self.add_attrs(idx.into(), RawAttrs::new(&field, &self.hygiene));
         }
         let end = self.next_field_idx();
         IdRange::new(start..end)
@@ -270,7 +269,7 @@ impl Ctx {
         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(), Attrs::new(&variant, &self.hygiene));
+                self.add_attrs(idx.into(), RawAttrs::new(&variant, &self.hygiene));
             }
         }
         let end = self.next_variant_idx();
@@ -438,7 +437,7 @@ impl Ctx {
             self.with_inherited_visibility(visibility, |this| {
                 list.assoc_items()
                     .filter_map(|item| {
-                        let attrs = Attrs::new(&item, &this.hygiene);
+                        let attrs = RawAttrs::new(&item, &this.hygiene);
                         this.collect_inner_items(item.syntax());
                         this.lower_assoc_item(&item).map(|item| {
                             this.add_attrs(ModItem::from(item).into(), attrs);
@@ -475,7 +474,7 @@ impl Ctx {
             .filter_map(|item| {
                 self.collect_inner_items(item.syntax());
                 let assoc = self.lower_assoc_item(&item)?;
-                let attrs = Attrs::new(&item, &self.hygiene);
+                let attrs = RawAttrs::new(&item, &self.hygiene);
                 self.add_attrs(ModItem::from(assoc).into(), attrs);
                 Some(assoc)
             })
@@ -486,8 +485,6 @@ impl Ctx {
     }
 
     fn lower_use(&mut self, use_item: &ast::Use) -> Vec<FileItemTreeId<Import>> {
-        // FIXME: cfg_attr
-        let is_prelude = use_item.has_atom_attr("prelude_import");
         let visibility = self.lower_visibility(use_item);
         let ast_id = self.source_ast_id_map.ast_id(use_item);
 
@@ -503,7 +500,6 @@ impl Ctx {
                     alias,
                     visibility,
                     is_glob,
-                    is_prelude,
                     ast_id,
                     index: imports.len(),
                 })));
@@ -523,10 +519,8 @@ impl Ctx {
         });
         let visibility = self.lower_visibility(extern_crate);
         let ast_id = self.source_ast_id_map.ast_id(extern_crate);
-        // FIXME: cfg_attr
-        let is_macro_use = extern_crate.has_atom_attr("macro_use");
 
-        let res = ExternCrate { name, alias, visibility, is_macro_use, ast_id };
+        let res = ExternCrate { name, alias, visibility, ast_id };
         Some(id(self.data().extern_crates.alloc(res)))
     }
 
@@ -560,7 +554,7 @@ impl Ctx {
             list.extern_items()
                 .filter_map(|item| {
                     self.collect_inner_items(item.syntax());
-                    let attrs = Attrs::new(&item, &self.hygiene);
+                    let attrs = RawAttrs::new(&item, &self.hygiene);
                     let id: ModItem = match item {
                         ast::ExternItem::Fn(ast) => {
                             let func_id = self.lower_function(&ast)?;
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 7e2199a9c..ba09a9126 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -425,6 +425,16 @@ impl HasModule for AdtId {
     }
 }
 
+impl HasModule for VariantId {
+    fn module(&self, db: &dyn db::DefDatabase) -> ModuleId {
+        match self {
+            VariantId::EnumVariantId(it) => it.parent.lookup(db).container.module(db),
+            VariantId::StructId(it) => it.lookup(db).container.module(db),
+            VariantId::UnionId(it) => it.lookup(db).container.module(db),
+        }
+    }
+}
+
 impl HasModule for DefWithBodyId {
     fn module(&self, db: &dyn db::DefDatabase) -> ModuleId {
         match self {
@@ -465,6 +475,26 @@ impl HasModule for StaticLoc {
     }
 }
 
+impl AttrDefId {
+    pub fn krate(&self, db: &dyn db::DefDatabase) -> CrateId {
+        match self {
+            AttrDefId::ModuleId(it) => it.krate,
+            AttrDefId::FieldId(it) => it.parent.module(db).krate,
+            AttrDefId::AdtId(it) => it.module(db).krate,
+            AttrDefId::FunctionId(it) => it.lookup(db).module(db).krate,
+            AttrDefId::EnumVariantId(it) => it.parent.lookup(db).container.module(db).krate,
+            AttrDefId::StaticId(it) => it.lookup(db).module(db).krate,
+            AttrDefId::ConstId(it) => it.lookup(db).module(db).krate,
+            AttrDefId::TraitId(it) => it.lookup(db).container.module(db).krate,
+            AttrDefId::TypeAliasId(it) => it.lookup(db).module(db).krate,
+            AttrDefId::ImplId(it) => it.lookup(db).container.module(db).krate,
+            // FIXME: `MacroDefId` should store the defining module, then this can implement
+            // `HasModule`
+            AttrDefId::MacroDefId(it) => it.krate,
+        }
+    }
+}
+
 /// A helper trait for converting to MacroCallId
 pub trait AsMacroCall {
     fn as_call_id(
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 1936348fb..a636ec77d 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -136,23 +136,35 @@ struct Import {
 }
 
 impl Import {
-    fn from_use(tree: &ItemTree, id: ItemTreeId<item_tree::Import>) -> Self {
+    fn from_use(
+        db: &dyn DefDatabase,
+        krate: CrateId,
+        tree: &ItemTree,
+        id: ItemTreeId<item_tree::Import>,
+    ) -> Self {
         let it = &tree[id.value];
+        let attrs = &tree.attrs(db, krate, ModItem::from(id.value).into());
         let visibility = &tree[it.visibility];
         Self {
             path: it.path.clone(),
             alias: it.alias.clone(),
             visibility: visibility.clone(),
             is_glob: it.is_glob,
-            is_prelude: it.is_prelude,
+            is_prelude: attrs.by_key("prelude_import").exists(),
             is_extern_crate: false,
             is_macro_use: false,
             source: ImportSource::Import(id),
         }
     }
 
-    fn from_extern_crate(tree: &ItemTree, id: ItemTreeId<item_tree::ExternCrate>) -> Self {
+    fn from_extern_crate(
+        db: &dyn DefDatabase,
+        krate: CrateId,
+        tree: &ItemTree,
+        id: ItemTreeId<item_tree::ExternCrate>,
+    ) -> Self {
         let it = &tree[id.value];
+        let attrs = &tree.attrs(db, krate, ModItem::from(id.value).into());
         let visibility = &tree[it.visibility];
         Self {
             path: ModPath::from_segments(PathKind::Plain, iter::once(it.name.clone())),
@@ -161,7 +173,7 @@ impl Import {
             is_glob: false,
             is_prelude: false,
             is_extern_crate: true,
-            is_macro_use: it.is_macro_use,
+            is_macro_use: attrs.by_key("macro_use").exists(),
             source: ImportSource::ExternCrate(id),
         }
     }
@@ -221,17 +233,20 @@ impl DefCollector<'_> {
         let item_tree = self.db.item_tree(file_id.into());
         let module_id = self.def_map.root;
         self.def_map.modules[module_id].origin = ModuleOrigin::CrateRoot { definition: file_id };
-        let mut root_collector = ModCollector {
-            def_collector: &mut *self,
-            macro_depth: 0,
-            module_id,
-            file_id: file_id.into(),
-            item_tree: &item_tree,
-            mod_dir: ModDir::root(),
-        };
-        if item_tree.top_level_attrs().cfg().map_or(true, |cfg| root_collector.is_cfg_enabled(&cfg))
+        if item_tree
+            .top_level_attrs(self.db, self.def_map.krate)
+            .cfg()
+            .map_or(true, |cfg| self.cfg_options.check(&cfg) != Some(false))
         {
-            root_collector.collect(item_tree.top_level_items());
+            ModCollector {
+                def_collector: &mut *self,
+                macro_depth: 0,
+                module_id,
+                file_id: file_id.into(),
+                item_tree: &item_tree,
+                mod_dir: ModDir::root(),
+            }
+            .collect(item_tree.top_level_items());
         }
 
         // main name resolution fixed-point loop.
@@ -905,6 +920,8 @@ struct ModCollector<'a, 'b> {
 
 impl ModCollector<'_, '_> {
     fn collect(&mut self, items: &[ModItem]) {
+        let krate = self.def_collector.def_map.krate;
+
         // Note: don't assert that inserted value is fresh: it's simply not true
         // for macros.
         self.def_collector.mod_dirs.insert(self.module_id, self.mod_dir.clone());
@@ -921,11 +938,16 @@ impl ModCollector<'_, '_> {
         // `#[macro_use] extern crate` is hoisted to imports macros before collecting
         // any other items.
         for item in items {
-            let attrs = self.item_tree.attrs((*item).into());
+            let attrs = self.item_tree.attrs(self.def_collector.db, krate, (*item).into());
             if attrs.cfg().map_or(true, |cfg| self.is_cfg_enabled(&cfg)) {
                 if let ModItem::ExternCrate(id) = item {
                     let import = self.item_tree[*id].clone();
-                    if import.is_macro_use {
+                    let attrs = self.item_tree.attrs(
+                        self.def_collector.db,
+                        krate,
+                        ModItem::from(*id).into(),
+                    );
+                    if attrs.by_key("macro_use").exists() {
                         self.def_collector.import_macros_from_extern_crate(self.module_id, &import);
                     }
                 }
@@ -933,7 +955,7 @@ impl ModCollector<'_, '_> {
         }
 
         for &item in items {
-            let attrs = self.item_tree.attrs(item.into());
+            let attrs = self.item_tree.attrs(self.def_collector.db, krate, item.into());
             if let Some(cfg) = attrs.cfg() {
                 if !self.is_cfg_enabled(&cfg) {
                     self.emit_unconfigured_diagnostic(item, &cfg);
@@ -946,11 +968,13 @@ impl ModCollector<'_, '_> {
 
             let mut def = None;
             match item {
-                ModItem::Mod(m) => self.collect_module(&self.item_tree[m], attrs),
+                ModItem::Mod(m) => self.collect_module(&self.item_tree[m], &attrs),
                 ModItem::Import(import_id) => {
                     self.def_collector.unresolved_imports.push(ImportDirective {
                         module_id: self.module_id,
                         import: Import::from_use(
+                            self.def_collector.db,
+                            krate,
                             &self.item_tree,
                             InFile::new(self.file_id, import_id),
                         ),
@@ -961,6 +985,8 @@ impl ModCollector<'_, '_> {
                     self.def_collector.unresolved_imports.push(ImportDirective {
                         module_id: self.module_id,
                         import: Import::from_extern_crate(
+                            self.def_collector.db,
+                            krate,
                             &self.item_tree,
                             InFile::new(self.file_id, import_id),
                         ),
@@ -975,7 +1001,11 @@ impl ModCollector<'_, '_> {
 
                     // "Macro 2.0" is not currently supported by rust-analyzer, but libcore uses it
                     // to define builtin macros, so we support at least that part.
-                    let attrs = self.item_tree.attrs(ModItem::from(id).into());
+                    let attrs = self.item_tree.attrs(
+                        self.def_collector.db,
+                        krate,
+                        ModItem::from(id).into(),
+                    );
                     if attrs.by_key("rustc_builtin_macro").exists() {
                         let krate = self.def_collector.def_map.krate;
                         let macro_id = find_builtin_macro(&mac.name, krate, ast_id)
@@ -1012,7 +1042,7 @@ impl ModCollector<'_, '_> {
                 ModItem::Function(id) => {
                     let func = &self.item_tree[id];
 
-                    self.collect_proc_macro_def(&func.name, attrs);
+                    self.collect_proc_macro_def(&func.name, &attrs);
 
                     def = Some(DefData {
                         id: FunctionLoc {
@@ -1032,7 +1062,7 @@ impl ModCollector<'_, '_> {
                     // FIXME: check attrs to see if this is an attribute macro invocation;
                     // in which case we don't add the invocation, just a single attribute
                     // macro invocation
-                    self.collect_derives(attrs, it.ast_id.upcast());
+                    self.collect_derives(&attrs, it.ast_id.upcast());
 
                     def = Some(DefData {
                         id: StructLoc { container, id: ItemTreeId::new(self.file_id, id) }
@@ -1049,7 +1079,7 @@ impl ModCollector<'_, '_> {
                     // FIXME: check attrs to see if this is an attribute macro invocation;
                     // in which case we don't add the invocation, just a single attribute
                     // macro invocation
-                    self.collect_derives(attrs, it.ast_id.upcast());
+                    self.collect_derives(&attrs, it.ast_id.upcast());
 
                     def = Some(DefData {
                         id: UnionLoc { container, id: ItemTreeId::new(self.file_id, id) }
@@ -1066,7 +1096,7 @@ impl ModCollector<'_, '_> {
                     // FIXME: check attrs to see if this is an attribute macro invocation;
                     // in which case we don't add the invocation, just a single attribute
                     // macro invocation
-                    self.collect_derives(attrs, it.ast_id.upcast());
+                    self.collect_derives(&attrs, it.ast_id.upcast());
 
                     def = Some(DefData {
                         id: EnumLoc { container, id: ItemTreeId::new(self.file_id, id) }
@@ -1259,20 +1289,20 @@ impl ModCollector<'_, '_> {
     }
 
     fn collect_derives(&mut self, attrs: &Attrs, ast_id: FileAstId<ast::Item>) {
-        for derive_subtree in attrs.by_key("derive").tt_values() {
-            // for #[derive(Copy, Clone)], `derive_subtree` is the `(Copy, Clone)` subtree
-            for tt in &derive_subtree.token_trees {
-                let ident = match &tt {
-                    tt::TokenTree::Leaf(tt::Leaf::Ident(ident)) => ident,
-                    tt::TokenTree::Leaf(tt::Leaf::Punct(_)) => continue, // , is ok
-                    _ => continue, // anything else would be an error (which we currently ignore)
-                };
-                let path = ModPath::from_tt_ident(ident);
-
-                let ast_id = AstIdWithPath::new(self.file_id, ast_id, path);
-                self.def_collector
-                    .unexpanded_attribute_macros
-                    .push(DeriveDirective { module_id: self.module_id, ast_id });
+        for derive in attrs.by_key("derive").attrs() {
+            match derive.parse_derive() {
+                Some(derive_macros) => {
+                    for path in derive_macros {
+                        let ast_id = AstIdWithPath::new(self.file_id, ast_id, path);
+                        self.def_collector
+                            .unexpanded_attribute_macros
+                            .push(DeriveDirective { module_id: self.module_id, ast_id });
+                    }
+                }
+                None => {
+                    // FIXME: diagnose
+                    log::debug!("malformed derive: {:?}", derive);
+                }
             }
         }
     }
@@ -1303,8 +1333,9 @@ impl ModCollector<'_, '_> {
     }
 
     fn collect_macro_rules(&mut self, id: FileItemTreeId<MacroRules>) {
+        let krate = self.def_collector.def_map.krate;
         let mac = &self.item_tree[id];
-        let attrs = self.item_tree.attrs(ModItem::from(id).into());
+        let attrs = self.item_tree.attrs(self.def_collector.db, krate, ModItem::from(id).into());
         let ast_id = InFile::new(self.file_id, mac.ast_id.upcast());
 
         let export_attr = attrs.by_key("macro_export");
diff --git a/crates/hir_def/src/nameres/tests.rs b/crates/hir_def/src/nameres/tests.rs
index a4d1fb8f3..c459fa66d 100644
--- a/crates/hir_def/src/nameres/tests.rs
+++ b/crates/hir_def/src/nameres/tests.rs
@@ -13,8 +13,8 @@ use test_utils::mark;
 
 use crate::{db::DefDatabase, nameres::*, test_db::TestDB};
 
-fn compute_crate_def_map(fixture: &str) -> Arc<CrateDefMap> {
-    let db = TestDB::with_files(fixture);
+fn compute_crate_def_map(ra_fixture: &str) -> Arc<CrateDefMap> {
+    let db = TestDB::with_files(ra_fixture);
     let krate = db.crate_graph().iter().next().unwrap();
     db.crate_def_map(krate)
 }
diff --git a/crates/hir_def/src/nameres/tests/diagnostics.rs b/crates/hir_def/src/nameres/tests/diagnostics.rs
index 1a7b98831..58d69d3c6 100644
--- a/crates/hir_def/src/nameres/tests/diagnostics.rs
+++ b/crates/hir_def/src/nameres/tests/diagnostics.rs
@@ -1,4 +1,5 @@
 use base_db::fixture::WithFixture;
+use test_utils::mark;
 
 use crate::test_db::TestDB;
 
@@ -119,3 +120,20 @@ fn inactive_item() {
         "#,
     );
 }
+
+/// Tests that `cfg` attributes behind `cfg_attr` is handled properly.
+#[test]
+fn inactive_via_cfg_attr() {
+    mark::check!(cfg_attr_active);
+    check_diagnostics(
+        r#"
+        //- /lib.rs
+          #[cfg_attr(not(never), cfg(no))] fn f() {}
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+
+          #[cfg_attr(not(never), cfg(not(no)))] fn f() {}
+
+          #[cfg_attr(never, cfg(no))] fn g() {}
+        "#,
+    );
+}
diff --git a/crates/hir_def/src/nameres/tests/macros.rs b/crates/hir_def/src/nameres/tests/macros.rs
index 6fe2ee78a..f9bf5bc72 100644
--- a/crates/hir_def/src/nameres/tests/macros.rs
+++ b/crates/hir_def/src/nameres/tests/macros.rs
@@ -632,11 +632,11 @@ pub struct bar;
 #[test]
 fn expand_derive() {
     let map = compute_crate_def_map(
-        "
+        r#"
         //- /main.rs crate:main deps:core
-        use core::*;
+        use core::Copy;
 
-        #[derive(Copy, Clone)]
+        #[derive(Copy, core::Clone)]
         struct Foo;
 
         //- /core.rs crate:core
@@ -645,7 +645,7 @@ fn expand_derive() {
 
         #[rustc_builtin_macro]
         pub macro Clone {}
-        ",
+        "#,
     );
     assert_eq!(map.modules[map.root].scope.impls().len(), 2);
 }
diff --git a/crates/hir_def/src/path.rs b/crates/hir_def/src/path.rs
index 00a69a8a6..e2bf85bbc 100644
--- a/crates/hir_def/src/path.rs
+++ b/crates/hir_def/src/path.rs
@@ -9,11 +9,8 @@ use std::{
 
 use crate::{body::LowerCtx, type_ref::LifetimeRef};
 use base_db::CrateId;
-use hir_expand::{
-    hygiene::Hygiene,
-    name::{AsName, Name},
-};
-use syntax::ast::{self};
+use hir_expand::{hygiene::Hygiene, name::Name};
+use syntax::ast;
 
 use crate::{
     type_ref::{TypeBound, TypeRef},
@@ -56,11 +53,6 @@ impl ModPath {
         ModPath { kind, segments }
     }
 
-    /// Converts an `tt::Ident` into a single-identifier `Path`.
-    pub(crate) fn from_tt_ident(ident: &tt::Ident) -> ModPath {
-        ident.as_name().into()
-    }
-
     /// Calls `cb` with all paths, represented by this use item.
     pub(crate) fn expand_use_item(
         item_src: InFile<ast::Use>,