26 files changed, 312 insertions, 119 deletions

diff --git a/crates/hir/src/has_source.rs b/crates/hir/src/has_source.rs
index 262002671..d57fad9ed 100644
--- a/crates/hir/src/has_source.rs
+++ b/crates/hir/src/has_source.rs
@@ -6,7 +6,7 @@ use hir_def::{
     src::{HasChildSource, HasSource as _},
     Lookup, VariantId,
 };
-use hir_expand::InFile;
+use hir_expand::{InFile, MacroDefKind};
 use syntax::ast;
 
 use crate::{
@@ -111,10 +111,17 @@ impl HasSource for TypeAlias {
     }
 }
 impl HasSource for MacroDef {
-    type Ast = ast::Macro;
+    type Ast = Either<ast::Macro, ast::Fn>;
     fn source(self, db: &dyn HirDatabase) -> Option<InFile<Self::Ast>> {
-        let ast_id = self.id.ast_id?;
-        Some(InFile { file_id: ast_id.file_id, value: ast_id.to_node(db.upcast()) })
+        Some(match &self.id.kind {
+            MacroDefKind::Declarative(id)
+            | MacroDefKind::BuiltIn(_, id)
+            | MacroDefKind::BuiltInDerive(_, id)
+            | MacroDefKind::BuiltInEager(_, id) => {
+                id.with_value(Either::Left(id.to_node(db.upcast())))
+            }
+            MacroDefKind::ProcMacro(_, id) => id.map(|_| Either::Right(id.to_node(db.upcast()))),
+        })
     }
 }
 impl HasSource for Impl {
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index b41a36a78..95cfde61c 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -1144,17 +1144,21 @@ impl MacroDef {
 
     /// XXX: this parses the file
     pub fn name(self, db: &dyn HirDatabase) -> Option<Name> {
-        self.source(db)?.value.name().map(|it| it.as_name())
+        match self.source(db)?.value {
+            Either::Left(it) => it.name().map(|it| it.as_name()),
+            Either::Right(it) => it.name().map(|it| it.as_name()),
+        }
     }
 
     /// Indicate it is a proc-macro
     pub fn is_proc_macro(&self) -> bool {
-        matches!(self.id.kind, MacroDefKind::ProcMacro(_))
+        matches!(self.id.kind, MacroDefKind::ProcMacro(..))
     }
 
     /// Indicate it is a derive macro
     pub fn is_derive_macro(&self) -> bool {
-        matches!(self.id.kind, MacroDefKind::ProcMacro(_) | MacroDefKind::BuiltInDerive(_))
+        // FIXME: wrong for `ProcMacro`
+        matches!(self.id.kind, MacroDefKind::ProcMacro(..) | MacroDefKind::BuiltInDerive(..))
     }
 }
 
diff --git a/crates/hir/src/semantics/source_to_def.rs b/crates/hir/src/semantics/source_to_def.rs
index c6ad5ecb5..762809fcd 100644
--- a/crates/hir/src/semantics/source_to_def.rs
+++ b/crates/hir/src/semantics/source_to_def.rs
@@ -195,12 +195,12 @@ impl SourceToDefCtx<'_, '_> {
         &mut self,
         src: InFile<ast::MacroRules>,
     ) -> Option<MacroDefId> {
-        let kind = MacroDefKind::Declarative;
+        let file_ast_id = self.db.ast_id_map(src.file_id).ast_id(&src.value);
+        let ast_id = AstId::new(src.file_id, file_ast_id.upcast());
+        let kind = MacroDefKind::Declarative(ast_id);
         let file_id = src.file_id.original_file(self.db.upcast());
         let krate = self.file_to_def(file_id).get(0).copied()?.krate();
-        let file_ast_id = self.db.ast_id_map(src.file_id).ast_id(&src.value);
-        let ast_id = Some(AstId::new(src.file_id, file_ast_id.upcast()));
-        Some(MacroDefId { krate, ast_id, kind, local_inner: false })
+        Some(MacroDefId { krate, kind, local_inner: false })
     }
 
     pub(super) fn find_container(&mut self, src: InFile<&SyntaxNode>) -> Option<ChildContainer> {
diff --git a/crates/hir_def/src/attr.rs b/crates/hir_def/src/attr.rs
index 739e3f5e3..1cab0e363 100644
--- a/crates/hir_def/src/attr.rs
+++ b/crates/hir_def/src/attr.rs
@@ -209,7 +209,7 @@ impl Attrs {
             },
             AttrDefId::TraitId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::MacroDefId(it) => {
-                it.ast_id.map_or_else(Default::default, |ast_id| attrs_from_ast(ast_id, db))
+                it.ast_id().map_or_else(Default::default, |ast_id| attrs_from_ast(ast_id, db))
             }
             AttrDefId::ImplId(it) => attrs_from_item_tree(it.lookup(db).id, db),
             AttrDefId::ConstId(it) => attrs_from_item_tree(it.lookup(db).id, db),
diff --git a/crates/hir_def/src/import_map.rs b/crates/hir_def/src/import_map.rs
index 369bc3350..960cabb5f 100644
--- a/crates/hir_def/src/import_map.rs
+++ b/crates/hir_def/src/import_map.rs
@@ -912,10 +912,10 @@ mod tests {
                 dep::fmt (t)
                 dep::format (f)
                 dep::Fmt (v)
-                dep::fmt::Display (t)
+                dep::Fmt (m)
                 dep::Fmt (t)
                 dep::fmt::Display::fmt (a)
-                dep::Fmt (m)
+                dep::fmt::Display (t)
             "#]],
         );
 
@@ -926,9 +926,9 @@ mod tests {
             expect![[r#"
                 dep::fmt (t)
                 dep::Fmt (v)
+                dep::Fmt (m)
                 dep::Fmt (t)
                 dep::fmt::Display::fmt (a)
-                dep::Fmt (m)
             "#]],
         );
 
@@ -939,10 +939,10 @@ mod tests {
             expect![[r#"
                 dep::fmt (t)
                 dep::Fmt (v)
-                dep::fmt::Display (t)
+                dep::Fmt (m)
                 dep::Fmt (t)
                 dep::fmt::Display::fmt (a)
-                dep::Fmt (m)
+                dep::fmt::Display (t)
             "#]],
         );
     }
@@ -980,10 +980,10 @@ mod tests {
             expect![[r#"
                 dep::fmt (t)
                 dep::Fmt (v)
-                dep::fmt::Display (t)
+                dep::Fmt (m)
                 dep::Fmt (t)
                 dep::fmt::Display::fmt (a)
-                dep::Fmt (m)
+                dep::fmt::Display (t)
             "#]],
         );
 
@@ -994,9 +994,9 @@ mod tests {
             expect![[r#"
                 dep::fmt (t)
                 dep::Fmt (v)
+                dep::Fmt (m)
                 dep::Fmt (t)
                 dep::fmt::Display::fmt (a)
-                dep::Fmt (m)
             "#]],
         );
     }
@@ -1058,8 +1058,8 @@ mod tests {
             Query::new("".to_string()).limit(2),
             expect![[r#"
                 dep::fmt (t)
-                dep::Fmt (t)
                 dep::Fmt (m)
+                dep::Fmt (t)
                 dep::Fmt (v)
             "#]],
         );
diff --git a/crates/hir_def/src/item_scope.rs b/crates/hir_def/src/item_scope.rs
index aafd73b60..f3ebe7c72 100644
--- a/crates/hir_def/src/item_scope.rs
+++ b/crates/hir_def/src/item_scope.rs
@@ -252,7 +252,7 @@ impl ItemScope {
             .for_each(|vis| *vis = Visibility::Module(this_module));
 
         for (mac, vis) in self.macros.values_mut() {
-            if let MacroDefKind::ProcMacro(_) = mac.kind {
+            if let MacroDefKind::ProcMacro(..) = mac.kind {
                 // FIXME: Technically this is insufficient since reexports of proc macros are also
                 // forbidden. Practically nobody does that.
                 continue;
diff --git a/crates/hir_def/src/item_tree.rs b/crates/hir_def/src/item_tree.rs
index 5f5b7151a..ae2475b4e 100644
--- a/crates/hir_def/src/item_tree.rs
+++ b/crates/hir_def/src/item_tree.rs
@@ -115,6 +115,10 @@ impl ItemTree {
                     // still need to collect inner items.
                     ctx.lower_inner_items(stmt.syntax())
                 },
+                ast::Item(item) => {
+                    // Macros can expand to stmt and other item, and we add it as top level item
+                    ctx.lower_single_item(item)
+                },
                 _ => {
                     panic!("cannot create item tree from {:?} {}", syntax, syntax);
                 },
diff --git a/crates/hir_def/src/item_tree/lower.rs b/crates/hir_def/src/item_tree/lower.rs
index 3f558edd8..d3fe1ce1e 100644
--- a/crates/hir_def/src/item_tree/lower.rs
+++ b/crates/hir_def/src/item_tree/lower.rs
@@ -87,6 +87,14 @@ impl Ctx {
         self.tree
     }
 
+    pub(super) fn lower_single_item(mut self, item: ast::Item) -> ItemTree {
+        self.tree.top_level = self
+            .lower_mod_item(&item, false)
+            .map(|item| item.0)
+            .unwrap_or_else(|| Default::default());
+        self.tree
+    }
+
     pub(super) fn lower_inner_items(mut self, within: &SyntaxNode) -> ItemTree {
         self.collect_inner_items(within);
         self.tree
diff --git a/crates/hir_def/src/lib.rs b/crates/hir_def/src/lib.rs
index 6758411a0..21add086d 100644
--- a/crates/hir_def/src/lib.rs
+++ b/crates/hir_def/src/lib.rs
@@ -650,7 +650,7 @@ fn macro_call_as_call_id(
 ) -> Result<Result<MacroCallId, ErrorEmitted>, UnresolvedMacro> {
     let def: MacroDefId = resolver(call.path.clone()).ok_or(UnresolvedMacro)?;
 
-    let res = if let MacroDefKind::BuiltInEager(_) = def.kind {
+    let res = if let MacroDefKind::BuiltInEager(..) = def.kind {
         let macro_call = InFile::new(call.ast_id.file_id, call.ast_id.to_node(db.upcast()));
         let hygiene = Hygiene::new(db.upcast(), call.ast_id.file_id);
 
diff --git a/crates/hir_def/src/nameres.rs b/crates/hir_def/src/nameres.rs
index c97be584e..1ac326f97 100644
--- a/crates/hir_def/src/nameres.rs
+++ b/crates/hir_def/src/nameres.rs
@@ -53,11 +53,12 @@ mod path_resolution;
 
 #[cfg(test)]
 mod tests;
+mod proc_macro;
 
 use std::sync::Arc;
 
 use base_db::{CrateId, Edition, FileId};
-use hir_expand::{diagnostics::DiagnosticSink, name::Name, InFile};
+use hir_expand::{diagnostics::DiagnosticSink, name::Name, InFile, MacroDefId};
 use la_arena::Arena;
 use profile::Count;
 use rustc_hash::FxHashMap;
@@ -73,6 +74,8 @@ use crate::{
     AstId, BlockId, BlockLoc, LocalModuleId, ModuleDefId, ModuleId,
 };
 
+use self::proc_macro::ProcMacroDef;
+
 /// Contains the results of (early) name resolution.
 ///
 /// A `DefMap` stores the module tree and the definitions that are in scope in every module after
@@ -95,6 +98,12 @@ pub struct DefMap {
     prelude: Option<ModuleId>,
     extern_prelude: FxHashMap<Name, ModuleDefId>,
 
+    /// Side table with additional proc. macro info, for use by name resolution in downstream
+    /// crates.
+    ///
+    /// (the primary purpose is to resolve derive helpers)
+    exported_proc_macros: FxHashMap<MacroDefId, ProcMacroDef>,
+
     edition: Edition,
     diagnostics: Vec<DefDiagnostic>,
 }
@@ -237,6 +246,7 @@ impl DefMap {
             krate,
             edition,
             extern_prelude: FxHashMap::default(),
+            exported_proc_macros: FxHashMap::default(),
             prelude: None,
             root,
             modules,
diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index d0fefb5af..dcedf7766 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -18,7 +18,6 @@ use hir_expand::{
 use hir_expand::{InFile, MacroCallLoc};
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::ast;
-use tt::{Leaf, TokenTree};
 
 use crate::{
     attr::Attrs,
@@ -42,6 +41,8 @@ use crate::{
     UnresolvedMacro,
 };
 
+use super::proc_macro::ProcMacroDef;
+
 const GLOB_RECURSION_LIMIT: usize = 100;
 const EXPANSION_DEPTH_LIMIT: usize = 128;
 const FIXED_POINT_LIMIT: usize = 8192;
@@ -353,24 +354,23 @@ impl DefCollector<'_> {
     /// use a dummy expander that always errors. This comes with the drawback of macros potentially
     /// going out of sync with what the build system sees (since we resolve using VFS state, but
     /// Cargo builds only on-disk files). We could and probably should add diagnostics for that.
-    fn resolve_proc_macro(&mut self, name: &Name) {
+    fn export_proc_macro(&mut self, def: ProcMacroDef, ast_id: AstId<ast::Fn>) {
         self.exports_proc_macros = true;
-        let macro_def = match self.proc_macros.iter().find(|(n, _)| n == name) {
+        let macro_def = match self.proc_macros.iter().find(|(n, _)| n == &def.name) {
             Some((_, expander)) => MacroDefId {
-                ast_id: None,
                 krate: self.def_map.krate,
-                kind: MacroDefKind::ProcMacro(*expander),
+                kind: MacroDefKind::ProcMacro(*expander, ast_id),
                 local_inner: false,
             },
             None => MacroDefId {
-                ast_id: None,
                 krate: self.def_map.krate,
-                kind: MacroDefKind::ProcMacro(ProcMacroExpander::dummy(self.def_map.krate)),
+                kind: MacroDefKind::ProcMacro(ProcMacroExpander::dummy(self.def_map.krate), ast_id),
                 local_inner: false,
             },
         };
 
-        self.define_proc_macro(name.clone(), macro_def);
+        self.define_proc_macro(def.name.clone(), macro_def);
+        self.def_map.exported_proc_macros.insert(macro_def, def);
     }
 
     /// Define a macro with `macro_rules`.
@@ -1118,7 +1118,8 @@ impl ModCollector<'_, '_> {
                 ModItem::Function(id) => {
                     let func = &self.item_tree[id];
 
-                    self.collect_proc_macro_def(&func.name, &attrs);
+                    let ast_id = InFile::new(self.file_id, func.ast_id);
+                    self.collect_proc_macro_def(&func.name, ast_id, &attrs);
 
                     def = Some(DefData {
                         id: FunctionLoc {
@@ -1385,28 +1386,11 @@ impl ModCollector<'_, '_> {
     }
 
     /// If `attrs` registers a procedural macro, collects its definition.
-    fn collect_proc_macro_def(&mut self, func_name: &Name, attrs: &Attrs) {
+    fn collect_proc_macro_def(&mut self, func_name: &Name, ast_id: AstId<ast::Fn>, attrs: &Attrs) {
         // FIXME: this should only be done in the root module of `proc-macro` crates, not everywhere
-        // FIXME: distinguish the type of macro
-        let macro_name = if attrs.by_key("proc_macro").exists()
-            || attrs.by_key("proc_macro_attribute").exists()
-        {
-            func_name.clone()
-        } else {
-            let derive = attrs.by_key("proc_macro_derive");
-            if let Some(arg) = derive.tt_values().next() {
-                if let [TokenTree::Leaf(Leaf::Ident(trait_name)), ..] = &*arg.token_trees {
-                    trait_name.as_name()
-                } else {
-                    log::trace!("malformed `#[proc_macro_derive]`: {}", arg);
-                    return;
-                }
-            } else {
-                return;
-            }
-        };
-
-        self.def_collector.resolve_proc_macro(&macro_name);
+        if let Some(proc_macro) = attrs.parse_proc_macro_decl(func_name) {
+            self.def_collector.export_proc_macro(proc_macro, ast_id);
+        }
     }
 
     fn collect_macro_rules(&mut self, id: FileItemTreeId<MacroRules>) {
@@ -1445,9 +1429,8 @@ impl ModCollector<'_, '_> {
 
         // Case 2: normal `macro_rules!` macro
         let macro_id = MacroDefId {
-            ast_id: Some(ast_id),
             krate: self.def_collector.def_map.krate,
-            kind: MacroDefKind::Declarative,
+            kind: MacroDefKind::Declarative(ast_id),
             local_inner: is_local_inner,
         };
         self.def_collector.define_macro(self.module_id, mac.name.clone(), macro_id, is_export);
diff --git a/crates/hir_def/src/nameres/proc_macro.rs b/crates/hir_def/src/nameres/proc_macro.rs
new file mode 100644
index 000000000..156598f19
--- /dev/null
+++ b/crates/hir_def/src/nameres/proc_macro.rs
@@ -0,0 +1,71 @@
+//! Nameres-specific procedural macro data and helpers.
+
+use hir_expand::name::{AsName, Name};
+use tt::{Leaf, TokenTree};
+
+use crate::attr::Attrs;
+
+#[derive(Debug, PartialEq, Eq)]
+pub(super) struct ProcMacroDef {
+    pub(super) name: Name,
+    pub(super) kind: ProcMacroKind,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub(super) enum ProcMacroKind {
+    CustomDerive { helpers: Box<[Name]> },
+    FnLike,
+    Attr,
+}
+
+impl Attrs {
+    #[rustfmt::skip]
+    pub(super) fn parse_proc_macro_decl(&self, func_name: &Name) -> Option<ProcMacroDef> {
+        if self.by_key("proc_macro").exists() {
+            Some(ProcMacroDef { name: func_name.clone(), kind: ProcMacroKind::FnLike })
+        } else if self.by_key("proc_macro_attribute").exists() {
+            Some(ProcMacroDef { name: func_name.clone(), kind: ProcMacroKind::Attr })
+        } else if self.by_key("proc_macro_derive").exists() {
+            let derive = self.by_key("proc_macro_derive").tt_values().next().unwrap();
+
+            match &*derive.token_trees {
+                // `#[proc_macro_derive(Trait)]`
+                [TokenTree::Leaf(Leaf::Ident(trait_name))] => Some(ProcMacroDef {
+                    name: trait_name.as_name(),
+                    kind: ProcMacroKind::CustomDerive { helpers: Box::new([]) },
+                }),
+
+                // `#[proc_macro_derive(Trait, attibutes(helper1, helper2, ...))]`
+                [
+                    TokenTree::Leaf(Leaf::Ident(trait_name)),
+                    TokenTree::Leaf(Leaf::Punct(comma)),
+                    TokenTree::Leaf(Leaf::Ident(attributes)),
+                    TokenTree::Subtree(helpers)
+                ] if comma.char == ',' && attributes.text == "attributes" =>
+                {
+                    let helpers = helpers.token_trees.iter()
+                        .filter(|tt| !matches!(tt, TokenTree::Leaf(Leaf::Punct(comma)) if comma.char == ','))
+                        .map(|tt| {
+                            match tt {
+                                TokenTree::Leaf(Leaf::Ident(helper)) => Some(helper.as_name()),
+                                _ => None
+                            }
+                        })
+                        .collect::<Option<Box<[_]>>>()?;
+
+                    Some(ProcMacroDef {
+                        name: trait_name.as_name(),
+                        kind: ProcMacroKind::CustomDerive { helpers },
+                    })
+                }
+
+                _ => {
+                    log::trace!("malformed `#[proc_macro_derive]`: {}", derive);
+                    None
+                }
+            }
+        } else {
+            None
+        }
+    }
+}
diff --git a/crates/hir_def/src/nameres/tests/macros.rs b/crates/hir_def/src/nameres/tests/macros.rs
index f65a655bf..d59d3c0db 100644
--- a/crates/hir_def/src/nameres/tests/macros.rs
+++ b/crates/hir_def/src/nameres/tests/macros.rs
@@ -1,4 +1,5 @@
 use super::*;
+use crate::nameres::proc_macro::{ProcMacroDef, ProcMacroKind};
 
 #[test]
 fn macro_rules_are_globally_visible() {
@@ -790,3 +791,28 @@ fn proc_macro_censoring() {
         "#]],
     );
 }
+
+#[test]
+fn collects_derive_helpers() {
+    let def_map = compute_crate_def_map(
+        r"
+        struct TokenStream;
+
+        #[proc_macro_derive(AnotherTrait, attributes(helper_attr))]
+        pub fn derive_macro_2(_item: TokenStream) -> TokenStream {
+            TokenStream
+        }
+        ",
+    );
+
+    assert_eq!(def_map.exported_proc_macros.len(), 1);
+    match def_map.exported_proc_macros.values().next() {
+        Some(ProcMacroDef { kind: ProcMacroKind::CustomDerive { helpers }, .. }) => {
+            match &**helpers {
+                [attr] => assert_eq!(attr.to_string(), "helper_attr"),
+                _ => unreachable!(),
+            }
+        }
+        _ => unreachable!(),
+    }
+}
diff --git a/crates/hir_expand/src/builtin_derive.rs b/crates/hir_expand/src/builtin_derive.rs
index 5e908b223..60fd2ebdd 100644
--- a/crates/hir_expand/src/builtin_derive.rs
+++ b/crates/hir_expand/src/builtin_derive.rs
@@ -61,8 +61,7 @@ pub fn find_builtin_derive(
     let expander = BuiltinDeriveExpander::find_by_name(ident)?;
     Some(MacroDefId {
         krate,
-        ast_id: Some(ast_id),
-        kind: MacroDefKind::BuiltInDerive(expander),
+        kind: MacroDefKind::BuiltInDerive(expander, ast_id),
         local_inner: false,
     })
 }
@@ -268,14 +267,13 @@ fn partial_ord_expand(
 mod tests {
     use base_db::{fixture::WithFixture, CrateId, SourceDatabase};
     use expect_test::{expect, Expect};
-    use name::{known, Name};
+    use name::AsName;
 
     use crate::{test_db::TestDB, AstId, MacroCallId, MacroCallKind, MacroCallLoc};
 
     use super::*;
 
-    fn expand_builtin_derive(ra_fixture: &str, name: Name) -> String {
-        let expander = BuiltinDeriveExpander::find_by_name(&name).unwrap();
+    fn expand_builtin_derive(ra_fixture: &str) -> String {
         let fixture = format!(
             r#"//- /main.rs crate:main deps:core
 $0
@@ -288,19 +286,34 @@ $0
 
         let (db, file_pos) = TestDB::with_position(&fixture);
         let file_id = file_pos.file_id;
+        let ast_id_map = db.ast_id_map(file_id.into());
         let parsed = db.parse(file_id);
-        let items: Vec<_> =
-            parsed.syntax_node().descendants().filter_map(ast::Item::cast).collect();
+        let macros: Vec<_> =
+            parsed.syntax_node().descendants().filter_map(ast::Macro::cast).collect();
+        let items: Vec<_> = parsed
+            .syntax_node()
+            .descendants()
+            .filter(|node| !ast::Macro::can_cast(node.kind()))
+            .filter_map(ast::Item::cast)
+            .collect();
+
+        assert_eq!(macros.len(), 1, "test must contain exactly 1 macro definition");
+        assert_eq!(items.len(), 1, "test must contain exactly 1 item");
+
+        let macro_ast_id = AstId::new(file_id.into(), ast_id_map.ast_id(&macros[0]));
+        let name = match &macros[0] {
+            ast::Macro::MacroRules(rules) => rules.name().unwrap().as_name(),
+            ast::Macro::MacroDef(def) => def.name().unwrap().as_name(),
+        };
 
-        let ast_id_map = db.ast_id_map(file_id.into());
+        let expander = BuiltinDeriveExpander::find_by_name(&name).unwrap();
 
         let attr_id = AstId::new(file_id.into(), ast_id_map.ast_id(&items[0]));
 
         let loc = MacroCallLoc {
             def: MacroDefId {
                 krate: CrateId(0),
-                ast_id: None,
-                kind: MacroDefKind::BuiltInDerive(expander),
+                kind: MacroDefKind::BuiltInDerive(expander, macro_ast_id),
                 local_inner: false,
             },
             krate: CrateId(0),
@@ -315,8 +328,8 @@ $0
         parsed.text().to_string()
     }
 
-    fn check_derive(ra_fixture: &str, name: Name, expected: Expect) {
-        let expanded = expand_builtin_derive(ra_fixture, name);
+    fn check_derive(ra_fixture: &str, expected: Expect) {
+        let expanded = expand_builtin_derive(ra_fixture);
         expected.assert_eq(&expanded);
     }
 
@@ -324,10 +337,10 @@ $0
     fn test_copy_expand_simple() {
         check_derive(
             r#"
+            macro Copy {}
             #[derive(Copy)]
             struct Foo;
             "#,
-            known::Copy,
             expect![["impl< >core::marker::CopyforFoo< >{}"]],
         );
     }
@@ -336,10 +349,10 @@ $0
     fn test_copy_expand_with_type_params() {
         check_derive(
             r#"
+            macro Copy {}
             #[derive(Copy)]
             struct Foo<A, B>;
             "#,
-            known::Copy,
             expect![["impl<T0:core::marker::Copy,T1:core::marker::Copy>core::marker::CopyforFoo<T0,T1>{}"]],
         );
     }
@@ -348,10 +361,10 @@ $0
     fn test_copy_expand_with_lifetimes() {
         check_derive(
             r#"
+            macro Copy {}
             #[derive(Copy)]
             struct Foo<A, B, 'a, 'b>;
             "#,
-            known::Copy,
             // We currently just ignore lifetimes
             expect![["impl<T0:core::marker::Copy,T1:core::marker::Copy>core::marker::CopyforFoo<T0,T1>{}"]],
         );
@@ -361,10 +374,10 @@ $0
     fn test_clone_expand() {
         check_derive(
             r#"
+            macro Clone {}
             #[derive(Clone)]
             struct Foo<A, B>;
             "#,
-            known::Clone,
             expect![["impl<T0:core::clone::Clone,T1:core::clone::Clone>core::clone::CloneforFoo<T0,T1>{}"]],
         );
     }
diff --git a/crates/hir_expand/src/builtin_macro.rs b/crates/hir_expand/src/builtin_macro.rs
index fce09a9e7..8529b43b6 100644
--- a/crates/hir_expand/src/builtin_macro.rs
+++ b/crates/hir_expand/src/builtin_macro.rs
@@ -71,14 +71,12 @@ pub fn find_builtin_macro(
     match kind {
         Either::Left(kind) => Some(MacroDefId {
             krate,
-            ast_id: Some(ast_id),
-            kind: MacroDefKind::BuiltIn(kind),
+            kind: MacroDefKind::BuiltIn(kind, ast_id),
             local_inner: false,
         }),
         Either::Right(kind) => Some(MacroDefId {
             krate,
-            ast_id: Some(ast_id),
-            kind: MacroDefKind::BuiltInEager(kind),
+            kind: MacroDefKind::BuiltInEager(kind, ast_id),
             local_inner: false,
         }),
     }
@@ -512,6 +510,7 @@ mod tests {
         let macro_call = macro_calls.pop().unwrap();
 
         let expander = find_by_name(&macro_rules.name().unwrap().as_name()).unwrap();
+        let ast_id = AstId::new(file_id.into(), ast_id_map.ast_id(&macro_rules));
 
         let krate = CrateId(0);
         let file_id = match expander {
@@ -519,8 +518,7 @@ mod tests {
                 // the first one should be a macro_rules
                 let def = MacroDefId {
                     krate: CrateId(0),
-                    ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_rules))),
-                    kind: MacroDefKind::BuiltIn(expander),
+                    kind: MacroDefKind::BuiltIn(expander, ast_id),
                     local_inner: false,
                 };
 
@@ -540,8 +538,7 @@ mod tests {
                 // the first one should be a macro_rules
                 let def = MacroDefId {
                     krate,
-                    ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_rules))),
-                    kind: MacroDefKind::BuiltInEager(expander),
+                    kind: MacroDefKind::BuiltInEager(expander, ast_id),
                     local_inner: false,
                 };
 
diff --git a/crates/hir_expand/src/db.rs b/crates/hir_expand/src/db.rs
index a3070f1f9..2748e25cf 100644
--- a/crates/hir_expand/src/db.rs
+++ b/crates/hir_expand/src/db.rs
@@ -130,8 +130,8 @@ fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdMap> {
 
 fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
     match id.kind {
-        MacroDefKind::Declarative => {
-            let macro_rules = match id.ast_id?.to_node(db) {
+        MacroDefKind::Declarative(ast_id) => {
+            let macro_rules = match ast_id.to_node(db) {
                 syntax::ast::Macro::MacroRules(mac) => mac,
                 syntax::ast::Macro::MacroDef(_) => return None,
             };
@@ -150,14 +150,14 @@ fn macro_def(db: &dyn AstDatabase, id: MacroDefId) -> Option<Arc<(TokenExpander,
             };
             Some(Arc::new((TokenExpander::MacroRules(rules), tmap)))
         }
-        MacroDefKind::BuiltIn(expander) => {
+        MacroDefKind::BuiltIn(expander, _) => {
             Some(Arc::new((TokenExpander::Builtin(expander), mbe::TokenMap::default())))
         }
-        MacroDefKind::BuiltInDerive(expander) => {
+        MacroDefKind::BuiltInDerive(expander, _) => {
             Some(Arc::new((TokenExpander::BuiltinDerive(expander), mbe::TokenMap::default())))
         }
-        MacroDefKind::BuiltInEager(_) => None,
-        MacroDefKind::ProcMacro(expander) => {
+        MacroDefKind::BuiltInEager(..) => None,
+        MacroDefKind::ProcMacro(expander, ..) => {
             Some(Arc::new((TokenExpander::ProcMacro(expander), mbe::TokenMap::default())))
         }
     }
@@ -269,7 +269,7 @@ fn expand_proc_macro(
     };
 
     let expander = match loc.def.kind {
-        MacroDefKind::ProcMacro(expander) => expander,
+        MacroDefKind::ProcMacro(expander, ..) => expander,
         _ => unreachable!(),
     };
 
diff --git a/crates/hir_expand/src/eager.rs b/crates/hir_expand/src/eager.rs
index dc618a9ee..04f374a29 100644
--- a/crates/hir_expand/src/eager.rs
+++ b/crates/hir_expand/src/eager.rs
@@ -140,7 +140,7 @@ pub fn expand_eager_macro(
     let subtree =
         diagnostic_sink.option(to_subtree(&result), || err("failed to parse macro result"))?;
 
-    if let MacroDefKind::BuiltInEager(eager) = def.kind {
+    if let MacroDefKind::BuiltInEager(eager, _) = def.kind {
         let res = eager.expand(db, arg_id, &subtree);
 
         let (subtree, fragment) = diagnostic_sink.expand_result_option(res)?;
@@ -193,7 +193,7 @@ fn eager_macro_recur(
         let def = diagnostic_sink
             .option_with(|| macro_resolver(child.path()?), || err("failed to resolve macro"))?;
         let insert = match def.kind {
-            MacroDefKind::BuiltInEager(_) => {
+            MacroDefKind::BuiltInEager(..) => {
                 let id: MacroCallId = expand_eager_macro(
                     db,
                     krate,
@@ -206,10 +206,10 @@ fn eager_macro_recur(
                 db.parse_or_expand(id.as_file())
                     .expect("successful macro expansion should be parseable")
             }
-            MacroDefKind::Declarative
-            | MacroDefKind::BuiltIn(_)
-            | MacroDefKind::BuiltInDerive(_)
-            | MacroDefKind::ProcMacro(_) => {
+            MacroDefKind::Declarative(_)
+            | MacroDefKind::BuiltIn(..)
+            | MacroDefKind::BuiltInDerive(..)
+            | MacroDefKind::ProcMacro(..) => {
                 let res = lazy_expand(db, &def, curr.with_value(child.clone()), krate);
                 let val = diagnostic_sink.expand_result_option(res)?;
 
diff --git a/crates/hir_expand/src/hygiene.rs b/crates/hir_expand/src/hygiene.rs
index 87cad326d..20cda1683 100644
--- a/crates/hir_expand/src/hygiene.rs
+++ b/crates/hir_expand/src/hygiene.rs
@@ -145,7 +145,7 @@ fn make_hygiene_info(
 ) -> Option<HygieneInfo> {
     let arg_tt = loc.kind.arg(db)?;
 
-    let def_offset = loc.def.ast_id.and_then(|id| {
+    let def_offset = loc.def.ast_id().and_then(|id| {
         let def_tt = match id.to_node(db) {
             ast::Macro::MacroRules(mac) => mac.token_tree()?.syntax().text_range().start(),
             ast::Macro::MacroDef(_) => return None,
@@ -176,13 +176,13 @@ impl HygieneFrame {
                     let loc = db.lookup_intern_macro(id);
                     let info = make_hygiene_info(db, macro_file, &loc);
                     match loc.def.kind {
-                        MacroDefKind::Declarative => {
+                        MacroDefKind::Declarative(_) => {
                             (info, Some(loc.def.krate), loc.def.local_inner)
                         }
-                        MacroDefKind::BuiltIn(_) => (info, Some(loc.def.krate), false),
-                        MacroDefKind::BuiltInDerive(_) => (info, None, false),
-                        MacroDefKind::BuiltInEager(_) => (info, None, false),
-                        MacroDefKind::ProcMacro(_) => (info, None, false),
+                        MacroDefKind::BuiltIn(..) => (info, Some(loc.def.krate), false),
+                        MacroDefKind::BuiltInDerive(..) => (info, None, false),
+                        MacroDefKind::BuiltInEager(..) => (info, None, false),
+                        MacroDefKind::ProcMacro(..) => (info, None, false),
                     }
                 }
             },
diff --git a/crates/hir_expand/src/lib.rs b/crates/hir_expand/src/lib.rs
index 7532d00b8..0a379651f 100644
--- a/crates/hir_expand/src/lib.rs
+++ b/crates/hir_expand/src/lib.rs
@@ -143,7 +143,7 @@ impl HirFileId {
 
                 let arg_tt = loc.kind.arg(db)?;
 
-                let def = loc.def.ast_id.and_then(|id| {
+                let def = loc.def.ast_id().and_then(|id| {
                     let def_tt = match id.to_node(db) {
                         ast::Macro::MacroRules(mac) => mac.token_tree()?,
                         ast::Macro::MacroDef(_) => return None,
@@ -180,7 +180,7 @@ impl HirFileId {
                 };
                 let loc: MacroCallLoc = db.lookup_intern_macro(lazy_id);
                 let item = match loc.def.kind {
-                    MacroDefKind::BuiltInDerive(_) => loc.kind.node(db),
+                    MacroDefKind::BuiltInDerive(..) => loc.kind.node(db),
                     _ => return None,
                 };
                 Some(item.with_value(ast::Item::cast(item.value.clone())?))
@@ -224,7 +224,6 @@ impl From<EagerMacroId> for MacroCallId {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct MacroDefId {
     pub krate: CrateId,
-    pub ast_id: Option<AstId<ast::Macro>>,
     pub kind: MacroDefKind,
 
     pub local_inner: bool,
@@ -239,16 +238,27 @@ impl MacroDefId {
     ) -> LazyMacroId {
         db.intern_macro(MacroCallLoc { def: self, krate, kind })
     }
+
+    pub fn ast_id(&self) -> Option<AstId<ast::Macro>> {
+        let id = match &self.kind {
+            MacroDefKind::Declarative(id) => id,
+            MacroDefKind::BuiltIn(_, id) => id,
+            MacroDefKind::BuiltInDerive(_, id) => id,
+            MacroDefKind::BuiltInEager(_, id) => id,
+            MacroDefKind::ProcMacro(..) => return None,
+        };
+        Some(*id)
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum MacroDefKind {
-    Declarative,
-    BuiltIn(BuiltinFnLikeExpander),
+    Declarative(AstId<ast::Macro>),
+    BuiltIn(BuiltinFnLikeExpander, AstId<ast::Macro>),
     // FIXME: maybe just Builtin and rename BuiltinFnLikeExpander to BuiltinExpander
-    BuiltInDerive(BuiltinDeriveExpander),
-    BuiltInEager(EagerExpander),
-    ProcMacro(ProcMacroExpander),
+    BuiltInDerive(BuiltinDeriveExpander, AstId<ast::Macro>),
+    BuiltInEager(EagerExpander, AstId<ast::Macro>),
+    ProcMacro(ProcMacroExpander, AstId<ast::Fn>),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
diff --git a/crates/hir_ty/src/diagnostics/decl_check.rs b/crates/hir_ty/src/diagnostics/decl_check.rs
index bfe239793..33a0f4d7d 100644
--- a/crates/hir_ty/src/diagnostics/decl_check.rs
+++ b/crates/hir_ty/src/diagnostics/decl_check.rs
@@ -102,7 +102,7 @@ impl<'a, 'b> DeclValidator<'a, 'b> {
         let db = self.db;
         for block_def_map in body.block_scopes.iter().filter_map(|block| db.block_def_map(*block)) {
             for (_, module) in block_def_map.modules() {
-                for (def_id, _) in module.scope.values() {
+                for def_id in module.scope.declarations() {
                     let mut validator = DeclValidator::new(self.db, self.krate, self.sink);
                     validator.validate_item(def_id);
                 }
@@ -902,4 +902,17 @@ extern {
             "#,
         );
     }
+
+    #[test]
+    fn infinite_loop_inner_items() {
+        check_diagnostics(
+            r#"
+fn qualify() {
+    mod foo {
+        use super::*;
+    }
+}
+            "#,
+        )
+    }
 }
diff --git a/crates/hir_ty/src/tests/macros.rs b/crates/hir_ty/src/tests/macros.rs
index af4f8bb11..c1e605740 100644
--- a/crates/hir_ty/src/tests/macros.rs
+++ b/crates/hir_ty/src/tests/macros.rs
@@ -232,6 +232,28 @@ fn expr_macro_expanded_in_stmts() {
 }
 
 #[test]
+fn recursive_inner_item_macro_rules() {
+    check_infer(
+        r#"
+        macro_rules! mac {
+            () => { mac!($)};
+            ($x:tt) => { macro_rules! blub { () => { 1 }; } };
+        }
+        fn foo() {
+            mac!();
+            let a = blub!();
+        }
+        "#,
+        expect![[r#"
+            !0..1 '1': i32
+            !0..7 'mac!($)': {unknown}
+            107..143 '{     ...!(); }': ()
+            129..130 'a': i32
+        "#]],
+    );
+}
+
+#[test]
 fn infer_type_value_macro_having_same_name() {
     check_infer(
         r#"
diff --git a/crates/ide/src/display/navigation_target.rs b/crates/ide/src/display/navigation_target.rs
index c086de163..364be260c 100644
--- a/crates/ide/src/display/navigation_target.rs
+++ b/crates/ide/src/display/navigation_target.rs
@@ -339,10 +339,14 @@ impl TryToNav for hir::Field {
 impl TryToNav for hir::MacroDef {
     fn try_to_nav(&self, db: &RootDatabase) -> Option<NavigationTarget> {
         let src = self.source(db)?;
-        log::debug!("nav target {:#?}", src.value.syntax());
+        let name_owner: &dyn ast::NameOwner = match &src.value {
+            Either::Left(it) => it,
+            Either::Right(it) => it,
+        };
+        log::debug!("nav target {:#?}", name_owner.syntax());
         let mut res = NavigationTarget::from_named(
             db,
-            src.as_ref().map(|it| it as &dyn ast::NameOwner),
+            src.as_ref().with_value(name_owner),
             SymbolKind::Macro,
         );
         res.docs = self.docs(db);
diff --git a/crates/ide/src/goto_definition.rs b/crates/ide/src/goto_definition.rs
index 598b47e41..473d48c2f 100644
--- a/crates/ide/src/goto_definition.rs
+++ b/crates/ide/src/goto_definition.rs
@@ -1176,4 +1176,21 @@ fn foo() { A { a$0: }; }
 "#,
         )
     }
+
+    #[test]
+    fn goto_proc_macro() {
+        check(
+            r#"
+//- /main.rs crate:main deps:mac
+use mac::fn_macro;
+
+fn_macro$0!();
+
+//- /mac.rs crate:mac
+#[proc_macro]
+fn fn_macro() {}
+ //^^^^^^^^
+            "#,
+        )
+    }
 }
diff --git a/crates/ide/src/hover.rs b/crates/ide/src/hover.rs
index 15d309d7d..a3fb17c0a 100644
--- a/crates/ide/src/hover.rs
+++ b/crates/ide/src/hover.rs
@@ -331,10 +331,16 @@ fn hover_for_definition(
 ) -> Option<Markup> {
     let mod_path = definition_mod_path(db, &def);
     return match def {
-        Definition::Macro(it) => {
-            let label = macro_label(&it.source(db)?.value);
-            from_def_source_labeled(db, it, Some(label), mod_path)
-        }
+        Definition::Macro(it) => match &it.source(db)?.value {
+            Either::Left(mac) => {
+                let label = macro_label(&mac);
+                from_def_source_labeled(db, it, Some(label), mod_path)
+            }
+            Either::Right(_) => {
+                // FIXME
+                None
+            }
+        },
         Definition::Field(def) => from_hir_fmt(db, def, mod_path),
         Definition::ModuleDef(it) => match it {
             ModuleDef::Module(it) => from_hir_fmt(db, it, mod_path),
diff --git a/crates/ide_completion/src/render/macro_.rs b/crates/ide_completion/src/render/macro_.rs
index 3fa21ba7c..7578ad50b 100644
--- a/crates/ide_completion/src/render/macro_.rs
+++ b/crates/ide_completion/src/render/macro_.rs
@@ -91,7 +91,7 @@ impl<'a> MacroRender<'a> {
     }
 
     fn detail(&self) -> Option<String> {
-        let ast_node = self.macro_.source(self.ctx.db())?.value;
+        let ast_node = self.macro_.source(self.ctx.db())?.value.left()?;
         Some(macro_label(&ast_node))
     }
 }
diff --git a/docs/user/manual.adoc b/docs/user/manual.adoc
index f4c37353c..dba2197de 100644
--- a/docs/user/manual.adoc
+++ b/docs/user/manual.adoc
@@ -384,11 +384,9 @@ If the LSP binary is not available, GNOME Builder can install it when opening a
 
 === Eclipse IDE
 
-Prerequisites: You have installed the <<rust-analyzer-language-server-binary,`rust-analyzer` binary>>.
-
 Support for Rust development in the Eclipse IDE is provided by link:https://github.com/eclipse/corrosion[Eclipse Corrosion].
-While it currently uses RLS as default, you can successfully configure it so the IDE will use `rust-analyzer` instead.
-To do so, with an Eclipse IDE where Corrosion is installed, just go to __Window > Preferences > Rust__ and edit the __Path to Rust Language Server__ entry to reference the path to `rust-analyzer`.
+If available in PATH or in some standard location, `rust-analyzer` is detected and powers editing of Rust files without further configuration.
+If `rust-analyzer` is not detected, Corrosion will prompt you for configuration of your Rust toolchain and language server with a link to the __Window > Preferences > Rust__ preference page; from here a button allows to download and configure `rust-analyzer`, but you can also reference another installation.
 You'll need to close and reopen all .rs and Cargo files, or to restart the IDE, for this change to take effect.
 
 == Configuration