Add expansion infrastructure for derive macros

crates/ra_hir/src/code_model/src.rs

@@ -105,7 +105,10 @@ impl HasSource for TypeAlias {
 impl HasSource for MacroDef {
     type Ast = ast::MacroCall;
     fn source(self, db: &impl DefDatabase) -> InFile<ast::MacroCall> {
-        InFile { file_id: self.id.ast_id.file_id, value: self.id.ast_id.to_node(db) }
+        InFile {
+            file_id: self.id.ast_id.expect("MacroDef without ast_id").file_id,
+            value: self.id.ast_id.expect("MacroDef without ast_id").to_node(db),
+        }
     }
 }
 impl HasSource for ImplBlock {

crates/ra_hir/src/from_source.rs

@@ -152,9 +152,9 @@ impl FromSource for MacroDef {
 
         let module_src = ModuleSource::from_child_node(db, src.as_ref().map(|it| it.syntax()));
         let module = Module::from_definition(db, InFile::new(src.file_id, module_src))?;
-        let krate = module.krate().crate_id();
+        let krate = Some(module.krate().crate_id());
 
-        let ast_id = AstId::new(src.file_id, db.ast_id_map(src.file_id).ast_id(&src.value));
+        let ast_id = Some(AstId::new(src.file_id, db.ast_id_map(src.file_id).ast_id(&src.value)));
 
         let id: MacroDefId = MacroDefId { krate, ast_id, kind };
         Some(MacroDef { id })

crates/ra_hir/src/source_binder.rs

@@ -20,7 +20,8 @@ use hir_def::{
     AssocItemId, DefWithBodyId,
 };
 use hir_expand::{
-    hygiene::Hygiene, name::AsName, AstId, HirFileId, InFile, MacroCallId, MacroFileKind,
+    hygiene::Hygiene, name::AsName, AstId, HirFileId, InFile, MacroCallId, MacroCallKind,
+    MacroFileKind,
 };
 use ra_syntax::{
     ast::{self, AstNode},
@@ -456,7 +457,7 @@ impl SourceAnalyzer {
             db.ast_id_map(macro_call.file_id).ast_id(macro_call.value),
         );
         Some(Expansion {
-            macro_call_id: def.as_call_id(db, ast_id),
+            macro_call_id: def.as_call_id(db, MacroCallKind::FnLike(ast_id)),
             macro_file_kind: to_macro_file_kind(macro_call.value),
         })
     }

crates/ra_hir_def/src/attr.rs

@@ -61,7 +61,9 @@ impl Attrs {
                 AdtId::UnionId(it) => attrs_from_ast(it.lookup_intern(db).ast_id, db),
             },
             AttrDefId::TraitId(it) => attrs_from_ast(it.lookup_intern(db).ast_id, db),
-            AttrDefId::MacroDefId(it) => attrs_from_ast(it.ast_id, db),
+            AttrDefId::MacroDefId(it) => {
+                it.ast_id.map_or_else(Default::default, |ast_id| attrs_from_ast(ast_id, db))
+            }
             AttrDefId::ImplId(it) => attrs_from_ast(it.lookup_intern(db).ast_id, db),
             AttrDefId::ConstId(it) => attrs_from_loc(it.lookup(db), db),
             AttrDefId::StaticId(it) => attrs_from_loc(it.lookup(db), db),

crates/ra_hir_def/src/body.rs

@@ -6,7 +6,9 @@ pub mod scope;
 use std::{ops::Index, sync::Arc};
 
 use either::Either;
-use hir_expand::{hygiene::Hygiene, AstId, HirFileId, InFile, MacroDefId, MacroFileKind};
+use hir_expand::{
+    hygiene::Hygiene, AstId, HirFileId, InFile, MacroCallKind, MacroDefId, MacroFileKind,
+};
 use ra_arena::{map::ArenaMap, Arena};
 use ra_syntax::{ast, AstNode, AstPtr};
 use rustc_hash::FxHashMap;
@@ -46,7 +48,7 @@ impl Expander {
 
         if let Some(path) = macro_call.path().and_then(|path| self.parse_path(path)) {
             if let Some(def) = self.resolve_path_as_macro(db, &path) {
-                let call_id = def.as_call_id(db, ast_id);
+                let call_id = def.as_call_id(db, MacroCallKind::FnLike(ast_id));
                 let file_id = call_id.as_file(MacroFileKind::Expr);
                 if let Some(node) = db.parse_or_expand(file_id) {
                     if let Some(expr) = ast::Expr::cast(node) {

crates/ra_hir_def/src/docs.rs

@@ -60,7 +60,7 @@ impl Documentation {
                 docs_from_ast(&src.value[it.local_id])
             }
             AttrDefId::TraitId(it) => docs_from_ast(&it.source(db).value),
-            AttrDefId::MacroDefId(it) => docs_from_ast(&it.ast_id.to_node(db)),
+            AttrDefId::MacroDefId(it) => docs_from_ast(&it.ast_id?.to_node(db)),
             AttrDefId::ConstId(it) => docs_from_ast(&it.lookup(db).source(db).value),
             AttrDefId::StaticId(it) => docs_from_ast(&it.lookup(db).source(db).value),
             AttrDefId::FunctionId(it) => docs_from_ast(&it.lookup(db).source(db).value),

crates/ra_hir_def/src/nameres/collector.rs

@@ -4,9 +4,10 @@
 //! resolves imports and expands macros.
 
 use hir_expand::{
+    builtin_derive::find_builtin_derive,
     builtin_macro::find_builtin_macro,
     name::{self, AsName, Name},
-    HirFileId, MacroCallId, MacroDefId, MacroDefKind, MacroFileKind,
+    HirFileId, MacroCallId, MacroCallKind, MacroDefId, MacroDefKind, MacroFileKind,
 };
 use ra_cfg::CfgOptions;
 use ra_db::{CrateId, FileId};
@@ -58,6 +59,7 @@ pub(super) fn collect_defs(db: &impl DefDatabase, mut def_map: CrateDefMap) -> C
         glob_imports: FxHashMap::default(),
         unresolved_imports: Vec::new(),
         unexpanded_macros: Vec::new(),
+        unexpanded_attribute_macros: Vec::new(),
         mod_dirs: FxHashMap::default(),
         macro_stack_monitor: MacroStackMonitor::default(),
         poison_macros: FxHashSet::default(),
@@ -102,6 +104,7 @@ struct DefCollector<'a, DB> {
     glob_imports: FxHashMap<LocalModuleId, Vec<(LocalModuleId, LocalImportId)>>,
     unresolved_imports: Vec<(LocalModuleId, LocalImportId, raw::ImportData)>,
     unexpanded_macros: Vec<(LocalModuleId, AstId<ast::MacroCall>, Path)>,
+    unexpanded_attribute_macros: Vec<(LocalModuleId, AstId<ast::ModuleItem>, Path)>,
     mod_dirs: FxHashMap<LocalModuleId, ModDir>,
 
     /// Some macro use `$tt:tt which mean we have to handle the macro perfectly
@@ -470,6 +473,8 @@ where
 
     fn resolve_macros(&mut self) -> ReachedFixedPoint {
         let mut macros = std::mem::replace(&mut self.unexpanded_macros, Vec::new());
+        let mut attribute_macros =
+            std::mem::replace(&mut self.unexpanded_attribute_macros, Vec::new());
         let mut resolved = Vec::new();
         let mut res = ReachedFixedPoint::Yes;
         macros.retain(|(module_id, ast_id, path)| {
@@ -482,7 +487,19 @@ where
             );
 
             if let Some(def) = resolved_res.resolved_def.take_macros() {
-                let call_id = def.as_call_id(self.db, *ast_id);
+                let call_id = def.as_call_id(self.db, MacroCallKind::FnLike(*ast_id));
+                resolved.push((*module_id, call_id, def));
+                res = ReachedFixedPoint::No;
+                return false;
+            }
+
+            true
+        });
+        attribute_macros.retain(|(module_id, ast_id, path)| {
+            let resolved_res = self.resolve_attribute_macro(path);
+
+            if let Some(def) = resolved_res {
+                let call_id = def.as_call_id(self.db, MacroCallKind::Attr(*ast_id));
                 resolved.push((*module_id, call_id, def));
                 res = ReachedFixedPoint::No;
                 return false;
@@ -492,6 +509,7 @@ where
         });
 
         self.unexpanded_macros = macros;
+        self.unexpanded_attribute_macros = attribute_macros;
 
         for (module_id, macro_call_id, macro_def_id) in resolved {
             self.collect_macro_expansion(module_id, macro_call_id, macro_def_id);
@@ -500,6 +518,20 @@ where
         res
     }
 
+    fn resolve_attribute_macro(&self, path: &Path) -> Option<MacroDefId> {
+        // FIXME this is currently super hacky, just enough to support the
+        // built-in derives
+        if let Some(name) = path.as_ident() {
+            // FIXME this should actually be handled with the normal name
+            // resolution; the std lib defines built-in stubs for the derives,
+            // but these are new-style `macro`s, which we don't support yet
+            if let Some(def_id) = find_builtin_derive(name) {
+                return Some(def_id);
+            }
+        }
+        None
+    }
+
     fn collect_macro_expansion(
         &mut self,
         module_id: LocalModuleId,
@@ -587,7 +619,9 @@ where
                         .def_collector
                         .unresolved_imports
                         .push((self.module_id, import_id, self.raw_items[import_id].clone())),
-                    raw::RawItemKind::Def(def) => self.define_def(&self.raw_items[def]),
+                    raw::RawItemKind::Def(def) => {
+                        self.define_def(&self.raw_items[def], &item.attrs)
+                    }
                     raw::RawItemKind::Macro(mac) => self.collect_macro(&self.raw_items[mac]),
                     raw::RawItemKind::Impl(imp) => {
                         let module = ModuleId {
@@ -682,10 +716,16 @@ where
         res
     }
 
-    fn define_def(&mut self, def: &raw::DefData) {
+    fn define_def(&mut self, def: &raw::DefData, attrs: &Attrs) {
         let module = ModuleId { krate: self.def_collector.def_map.krate, local_id: self.module_id };
         let ctx = LocationCtx::new(self.def_collector.db, module, self.file_id);
 
+        // 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, def);
+
         let name = def.name.clone();
         let def: PerNs = match def.kind {
             raw::DefKind::Function(ast_id) => {
@@ -736,6 +776,23 @@ where
         self.def_collector.update(self.module_id, None, &[(name, resolution)])
     }
 
+    fn collect_derives(&mut self, attrs: &Attrs, def: &raw::DefData) {
+        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 = Path::from_tt_ident(ident);
+
+                let ast_id = AstId::new(self.file_id, def.kind.ast_id());
+                self.def_collector.unexpanded_attribute_macros.push((self.module_id, ast_id, path));
+            }
+        }
+    }
+
     fn collect_macro(&mut self, mac: &raw::MacroData) {
         let ast_id = AstId::new(self.file_id, mac.ast_id);
 
@@ -759,8 +816,8 @@ where
         if is_macro_rules(&mac.path) {
             if let Some(name) = &mac.name {
                 let macro_id = MacroDefId {
-                    ast_id,
+                    ast_id: Some(ast_id),
-                    krate: self.def_collector.def_map.krate,
+                    krate: Some(self.def_collector.def_map.krate),
                     kind: MacroDefKind::Declarative,
                 };
                 self.def_collector.define_macro(self.module_id, name.clone(), macro_id, mac.export);
@@ -773,7 +830,8 @@ where
         if let Some(macro_def) = mac.path.as_ident().and_then(|name| {
             self.def_collector.def_map[self.module_id].scope.get_legacy_macro(&name)
         }) {
-            let macro_call_id = macro_def.as_call_id(self.def_collector.db, ast_id);
+            let macro_call_id =
+                macro_def.as_call_id(self.def_collector.db, MacroCallKind::FnLike(ast_id));
 
             self.def_collector.collect_macro_expansion(self.module_id, macro_call_id, macro_def);
             return;
@@ -829,6 +887,7 @@ mod tests {
             glob_imports: FxHashMap::default(),
             unresolved_imports: Vec::new(),
             unexpanded_macros: Vec::new(),
+            unexpanded_attribute_macros: Vec::new(),
             mod_dirs: FxHashMap::default(),
             macro_stack_monitor: monitor,
             poison_macros: FxHashSet::default(),

crates/ra_hir_def/src/nameres/raw.rs

@@ -184,6 +184,21 @@ pub(super) enum DefKind {
     TypeAlias(FileAstId<ast::TypeAliasDef>),
 }
 
+impl DefKind {
+    pub fn ast_id(&self) -> FileAstId<ast::ModuleItem> {
+        match self {
+            DefKind::Function(it) => it.upcast(),
+            DefKind::Struct(it) => it.upcast(),
+            DefKind::Union(it) => it.upcast(),
+            DefKind::Enum(it) => it.upcast(),
+            DefKind::Const(it) => it.upcast(),
+            DefKind::Static(it) => it.upcast(),
+            DefKind::Trait(it) => it.upcast(),
+            DefKind::TypeAlias(it) => it.upcast(),
+        }
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub(super) struct Macro(RawId);
 impl_arena_id!(Macro);

crates/ra_hir_def/src/nameres/tests/macros.rs

@@ -600,3 +600,27 @@ fn macro_dollar_crate_is_correct_in_indirect_deps() {
         ⋮bar: t v
     "###);
 }
+
+#[test]
+fn expand_derive() {
+    let map = compute_crate_def_map(
+        "
+        //- /main.rs
+        #[derive(Clone)]
+        struct Foo;
+        ",
+    );
+    assert_eq!(map.modules[map.root].impls.len(), 1);
+}
+
+#[test]
+fn expand_multiple_derive() {
+    let map = compute_crate_def_map(
+        "
+        //- /main.rs
+        #[derive(Copy, Clone)]
+        struct Foo;
+        ",
+    );
+    assert_eq!(map.modules[map.root].impls.len(), 2);
+}

crates/ra_hir_def/src/path.rs

@@ -199,6 +199,11 @@ impl Path {
         name_ref.as_name().into()
     }
 
+    /// Converts an `tt::Ident` into a single-identifier `Path`.
+    pub(crate) fn from_tt_ident(ident: &tt::Ident) -> Path {
+        ident.as_name().into()
+    }
+
     /// `true` is this path is a single identifier, like `foo`
     pub fn is_ident(&self) -> bool {
         self.kind == PathKind::Plain && self.segments.len() == 1

crates/ra_hir_expand/src/ast_id_map.rs

@@ -39,6 +39,16 @@ impl<N: AstNode> Hash for FileAstId<N> {
     }
 }
 
+impl<N: AstNode> FileAstId<N> {
+    // Can't make this a From implementation because of coherence
+    pub fn upcast<M: AstNode>(self) -> FileAstId<M>
+    where
+        M: From<N>,
+    {
+        FileAstId { raw: self.raw, _ty: PhantomData }
+    }
+}
+
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 struct ErasedFileAstId(RawId);
 impl_arena_id!(ErasedFileAstId);
@@ -53,7 +63,7 @@ impl AstIdMap {
     pub(crate) fn from_source(node: &SyntaxNode) -> AstIdMap {
         assert!(node.parent().is_none());
         let mut res = AstIdMap { arena: Arena::default() };
-        // By walking the tree in bread-first order we make sure that parents
+        // By walking the tree in breadth-first order we make sure that parents
         // get lower ids then children. That is, adding a new child does not
         // change parent's id. This means that, say, adding a new function to a
         // trait does not change ids of top-level items, which helps caching.

crates/ra_hir_expand/src/builtin_derive.rs

@@ -0,0 +1,64 @@
+//! Builtin derives.
+use crate::db::AstDatabase;
+use crate::{name, MacroCallId, MacroDefId, MacroDefKind};
+
+use crate::quote;
+
+macro_rules! register_builtin {
+    ( $(($name:ident, $kind: ident) => $expand:ident),* ) => {
+        #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+        pub enum BuiltinDeriveExpander {
+            $($kind),*
+        }
+
+        impl BuiltinDeriveExpander {
+            pub fn expand(
+                &self,
+                db: &dyn AstDatabase,
+                id: MacroCallId,
+                tt: &tt::Subtree,
+            ) -> Result<tt::Subtree, mbe::ExpandError> {
+                let expander = match *self {
+                    $( BuiltinDeriveExpander::$kind => $expand, )*
+                };
+                expander(db, id, tt)
+            }
+        }
+
+        pub fn find_builtin_derive(ident: &name::Name) -> Option<MacroDefId> {
+            let kind = match ident {
+                 $( id if id == &name::$name => BuiltinDeriveExpander::$kind, )*
+                 _ => return None,
+            };
+
+            Some(MacroDefId { krate: None, ast_id: None, kind: MacroDefKind::BuiltInDerive(kind) })
+        }
+    };
+}
+
+register_builtin! {
+    (COPY_TRAIT, Copy) => copy_expand,
+    (CLONE_TRAIT, Clone) => clone_expand
+}
+
+fn copy_expand(
+    _db: &dyn AstDatabase,
+    _id: MacroCallId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    let expanded = quote! {
+        impl Copy for Foo {}
+    };
+    Ok(expanded)
+}
+
+fn clone_expand(
+    _db: &dyn AstDatabase,
+    _id: MacroCallId,
+    _tt: &tt::Subtree,
+) -> Result<tt::Subtree, mbe::ExpandError> {
+    let expanded = quote! {
+        impl Clone for Foo {}
+    };
+    Ok(expanded)
+}

crates/ra_hir_expand/src/builtin_macro.rs

@@ -39,7 +39,7 @@ macro_rules! register_builtin {
                  _ => return None,
             };
 
-            Some(MacroDefId { krate, ast_id, kind: MacroDefKind::BuiltIn(kind) })
+            Some(MacroDefId { krate: Some(krate), ast_id: Some(ast_id), kind: MacroDefKind::BuiltIn(kind) })
         }
     };
 }
@@ -82,10 +82,9 @@ fn line_expand(
     _tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
     let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
 
-    let arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+    let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
-    let arg_start = arg.syntax().text_range().start();
+    let arg_start = arg.text_range().start();
 
     let file = id.as_file(MacroFileKind::Expr);
     let line_num = to_line_number(db, file, arg_start);
@@ -103,11 +102,10 @@ fn stringify_expand(
     _tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
     let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
 
     let macro_content = {
-        let arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+        let arg = loc.kind.arg(db).ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
-        let macro_args = arg.syntax().clone();
+        let macro_args = arg.clone();
         let text = macro_args.text();
         let without_parens = TextUnit::of_char('(')..text.len() - TextUnit::of_char(')');
         text.slice(without_parens).to_string()
@@ -148,7 +146,10 @@ fn column_expand(
     _tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
     let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
+    let macro_call = match loc.kind {
+        crate::MacroCallKind::FnLike(ast_id) => ast_id.to_node(db),
+        _ => panic!("column macro called as attr"),
+    };
 
     let _arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
     let col_start = macro_call.syntax().text_range().start();
@@ -164,15 +165,10 @@ fn column_expand(
 }
 
 fn file_expand(
-    db: &dyn AstDatabase,
+    _db: &dyn AstDatabase,
-    id: MacroCallId,
+    _id: MacroCallId,
     _tt: &tt::Subtree,
 ) -> Result<tt::Subtree, mbe::ExpandError> {
-    let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
-
-    let _ = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
-
     // FIXME: RA purposefully lacks knowledge of absolute file names
     // so just return "".
     let file_name = "";
@@ -207,7 +203,7 @@ fn compile_error_expand(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::{test_db::TestDB, MacroCallLoc};
+    use crate::{test_db::TestDB, MacroCallKind, MacroCallLoc};
     use ra_db::{fixture::WithFixture, SourceDatabase};
 
     fn expand_builtin_macro(s: &str, expander: BuiltinFnLikeExpander) -> String {
@@ -220,14 +216,17 @@ mod tests {
 
         // the first one should be a macro_rules
         let def = MacroDefId {
-            krate: CrateId(0),
+            krate: Some(CrateId(0)),
-            ast_id: AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0])),
+            ast_id: Some(AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[0]))),
             kind: MacroDefKind::BuiltIn(expander),
         };
 
         let loc = MacroCallLoc {
             def,
-            ast_id: AstId::new(file_id.into(), ast_id_map.ast_id(&macro_calls[1])),
+            kind: MacroCallKind::FnLike(AstId::new(
+                file_id.into(),
+                ast_id_map.ast_id(&macro_calls[1]),
+            )),
         };
 
         let id = db.intern_macro(loc);

crates/ra_hir_expand/src/db.rs

@@ -9,14 +9,15 @@ use ra_prof::profile;
 use ra_syntax::{AstNode, Parse, SyntaxNode};
 
 use crate::{
-    ast_id_map::AstIdMap, BuiltinFnLikeExpander, HirFileId, HirFileIdRepr, MacroCallId,
+    ast_id_map::AstIdMap, BuiltinDeriveExpander, BuiltinFnLikeExpander, HirFileId, HirFileIdRepr,
-    MacroCallLoc, MacroDefId, MacroDefKind, MacroFile, MacroFileKind,
+    MacroCallId, MacroCallLoc, MacroDefId, MacroDefKind, MacroFile, MacroFileKind,
 };
 
 #[derive(Debug, Clone, Eq, PartialEq)]
 pub enum TokenExpander {
     MacroRules(mbe::MacroRules),
     Builtin(BuiltinFnLikeExpander),
+    BuiltinDerive(BuiltinDeriveExpander),
 }
 
 impl TokenExpander {
@@ -29,6 +30,7 @@ impl TokenExpander {
         match self {
             TokenExpander::MacroRules(it) => it.expand(tt),
             TokenExpander::Builtin(it) => it.expand(db, id, tt),
+            TokenExpander::BuiltinDerive(it) => it.expand(db, id, tt),
         }
     }
 
@@ -36,6 +38,7 @@ impl TokenExpander {
         match self {
             TokenExpander::MacroRules(it) => it.map_id_down(id),
             TokenExpander::Builtin(..) => id,
+            TokenExpander::BuiltinDerive(..) => id,
         }
     }
 
@@ -43,6 +46,7 @@ impl TokenExpander {
         match self {
             TokenExpander::MacroRules(it) => it.map_id_up(id),
             TokenExpander::Builtin(..) => (id, mbe::Origin::Def),
+            TokenExpander::BuiltinDerive(..) => (id, mbe::Origin::Def),
         }
     }
 }
@@ -76,7 +80,7 @@ pub(crate) fn macro_def(
 ) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
     match id.kind {
         MacroDefKind::Declarative => {
-            let macro_call = id.ast_id.to_node(db);
+            let macro_call = id.ast_id?.to_node(db);
             let arg = macro_call.token_tree()?;
             let (tt, tmap) = mbe::ast_to_token_tree(&arg).or_else(|| {
                 log::warn!("fail on macro_def to token tree: {:#?}", arg);
@@ -91,6 +95,10 @@ pub(crate) fn macro_def(
         MacroDefKind::BuiltIn(expander) => {
             Some(Arc::new((TokenExpander::Builtin(expander.clone()), mbe::TokenMap::default())))
         }
+        MacroDefKind::BuiltInDerive(expander) => Some(Arc::new((
+            TokenExpander::BuiltinDerive(expander.clone()),
+            mbe::TokenMap::default(),
+        ))),
     }
 }
 
@@ -99,9 +107,8 @@ pub(crate) fn macro_arg(
     id: MacroCallId,
 ) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>> {
     let loc = db.lookup_intern_macro(id);
-    let macro_call = loc.ast_id.to_node(db);
+    let arg = loc.kind.arg(db)?;
-    let arg = macro_call.token_tree()?;
+    let (tt, tmap) = mbe::syntax_node_to_token_tree(&arg)?;
-    let (tt, tmap) = mbe::ast_to_token_tree(&arg)?;
     Some(Arc::new((tt, tmap)))
 }
 

crates/ra_hir_expand/src/hygiene.rs

@@ -25,8 +25,9 @@ impl Hygiene {
             HirFileIdRepr::MacroFile(macro_file) => {
                 let loc = db.lookup_intern_macro(macro_file.macro_call_id);
                 match loc.def.kind {
-                    MacroDefKind::Declarative => Some(loc.def.krate),
+                    MacroDefKind::Declarative => loc.def.krate,
                     MacroDefKind::BuiltIn(_) => None,
+                    MacroDefKind::BuiltInDerive(_) => None,
                 }
             }
         };

crates/ra_hir_expand/src/lib.rs

@@ -9,6 +9,7 @@ pub mod ast_id_map;
 pub mod name;
 pub mod hygiene;
 pub mod diagnostics;
+pub mod builtin_derive;
 pub mod builtin_macro;
 pub mod quote;
 
@@ -23,6 +24,7 @@ use ra_syntax::{
 };
 
 use crate::ast_id_map::FileAstId;
+use crate::builtin_derive::BuiltinDeriveExpander;
 use crate::builtin_macro::BuiltinFnLikeExpander;
 
 #[cfg(test)]
@@ -69,7 +71,7 @@ impl HirFileId {
             HirFileIdRepr::FileId(file_id) => file_id,
             HirFileIdRepr::MacroFile(macro_file) => {
                 let loc = db.lookup_intern_macro(macro_file.macro_call_id);
-                loc.ast_id.file_id.original_file(db)
+                loc.kind.file_id().original_file(db)
             }
         }
     }
@@ -81,8 +83,8 @@ impl HirFileId {
             HirFileIdRepr::MacroFile(macro_file) => {
                 let loc: MacroCallLoc = db.lookup_intern_macro(macro_file.macro_call_id);
 
-                let arg_tt = loc.ast_id.to_node(db).token_tree()?;
+                let arg_tt = loc.kind.arg(db)?;
-                let def_tt = loc.def.ast_id.to_node(db).token_tree()?;
+                let def_tt = loc.def.ast_id?.to_node(db).token_tree()?;
 
                 let macro_def = db.macro_def(loc.def)?;
                 let (parse, exp_map) = db.parse_macro(macro_file)?;
@@ -90,8 +92,8 @@ impl HirFileId {
 
                 Some(ExpansionInfo {
                     expanded: InFile::new(self, parse.syntax_node()),
-                    arg: InFile::new(loc.ast_id.file_id, arg_tt),
+                    arg: InFile::new(loc.kind.file_id(), arg_tt),
-                    def: InFile::new(loc.ast_id.file_id, def_tt),
+                    def: InFile::new(loc.def.ast_id?.file_id, def_tt),
                     macro_arg,
                     macro_def,
                     exp_map,
@@ -129,18 +131,20 @@ impl salsa::InternKey for MacroCallId {
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct MacroDefId {
-    pub krate: CrateId,
+    // FIXME: krate and ast_id are currently optional because we don't have a
-    pub ast_id: AstId<ast::MacroCall>,
+    // definition location for built-in derives. There is one, though: the
+    // standard library defines them. The problem is that it uses the new
+    // `macro` syntax for this, which we don't support yet. As soon as we do
+    // (which will probably require touching this code), we can instead use
+    // that (and also remove the hacks for resolving built-in derives).
+    pub krate: Option<CrateId>,
+    pub ast_id: Option<AstId<ast::MacroCall>>,
     pub kind: MacroDefKind,
 }
 
 impl MacroDefId {
-    pub fn as_call_id(
+    pub fn as_call_id(self, db: &dyn db::AstDatabase, kind: MacroCallKind) -> MacroCallId {
-        self,
+        db.intern_macro(MacroCallLoc { def: self, kind })
-        db: &dyn db::AstDatabase,
-        ast_id: AstId<ast::MacroCall>,
-    ) -> MacroCallId {
-        db.intern_macro(MacroCallLoc { def: self, ast_id })
     }
 }
 
@@ -148,12 +152,38 @@ impl MacroDefId {
 pub enum MacroDefKind {
     Declarative,
     BuiltIn(BuiltinFnLikeExpander),
+    // FIXME: maybe just Builtin and rename BuiltinFnLikeExpander to BuiltinExpander
+    BuiltInDerive(BuiltinDeriveExpander),
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct MacroCallLoc {
     pub(crate) def: MacroDefId,
-    pub(crate) ast_id: AstId<ast::MacroCall>,
+    pub(crate) kind: MacroCallKind,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub enum MacroCallKind {
+    FnLike(AstId<ast::MacroCall>),
+    Attr(AstId<ast::ModuleItem>),
+}
+
+impl MacroCallKind {
+    pub fn file_id(&self) -> HirFileId {
+        match self {
+            MacroCallKind::FnLike(ast_id) => ast_id.file_id,
+            MacroCallKind::Attr(ast_id) => ast_id.file_id,
+        }
+    }
+
+    pub fn arg(&self, db: &dyn db::AstDatabase) -> Option<SyntaxNode> {
+        match self {
+            MacroCallKind::FnLike(ast_id) => {
+                Some(ast_id.to_node(db).token_tree()?.syntax().clone())
+            }
+            MacroCallKind::Attr(ast_id) => Some(ast_id.to_node(db).syntax().clone()),
+        }
+    }
 }
 
 impl MacroCallId {
@@ -167,7 +197,7 @@ impl MacroCallId {
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ExpansionInfo {
     expanded: InFile<SyntaxNode>,
-    arg: InFile<ast::TokenTree>,
+    arg: InFile<SyntaxNode>,
     def: InFile<ast::TokenTree>,
 
     macro_def: Arc<(db::TokenExpander, mbe::TokenMap)>,
@@ -178,8 +208,7 @@ pub struct ExpansionInfo {
 impl ExpansionInfo {
     pub fn map_token_down(&self, token: InFile<&SyntaxToken>) -> Option<InFile<SyntaxToken>> {
         assert_eq!(token.file_id, self.arg.file_id);
-        let range =
+        let range = token.value.text_range().checked_sub(self.arg.value.text_range().start())?;
-            token.value.text_range().checked_sub(self.arg.value.syntax().text_range().start())?;
         let token_id = self.macro_arg.1.token_by_range(range)?;
         let token_id = self.macro_def.0.map_id_down(token_id);
 
@@ -195,15 +224,14 @@ impl ExpansionInfo {
 
         let (token_id, origin) = self.macro_def.0.map_id_up(token_id);
         let (token_map, tt) = match origin {
-            mbe::Origin::Call => (&self.macro_arg.1, &self.arg),
+            mbe::Origin::Call => (&self.macro_arg.1, self.arg.clone()),
-            mbe::Origin::Def => (&self.macro_def.1, &self.def),
+            mbe::Origin::Def => {
+                (&self.macro_def.1, self.def.as_ref().map(|tt| tt.syntax().clone()))
+            }
         };
 
         let range = token_map.range_by_token(token_id)?;
-        let token = algo::find_covering_element(
+        let token = algo::find_covering_element(&tt.value, range + tt.value.text_range().start())
-            tt.value.syntax(),
-            range + tt.value.syntax().text_range().start(),
-        )
             .into_token()?;
         Some(tt.with_value(token))
     }

crates/ra_hir_expand/src/name.rs

@@ -83,6 +83,12 @@ impl AsName for ast::Name {
     }
 }
 
+impl AsName for tt::Ident {
+    fn as_name(&self) -> Name {
+        Name::resolve(&self.text)
+    }
+}
+
 impl AsName for ast::FieldKind {
     fn as_name(&self) -> Name {
         match self {
@@ -153,3 +159,7 @@ pub const COLUMN_MACRO: Name = Name::new_inline_ascii(6, b"column");
 pub const COMPILE_ERROR_MACRO: Name = Name::new_inline_ascii(13, b"compile_error");
 pub const LINE_MACRO: Name = Name::new_inline_ascii(4, b"line");
 pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(9, b"stringify");
+
+// Builtin derives
+pub const COPY_TRAIT: Name = Name::new_inline_ascii(4, b"Copy");
+pub const CLONE_TRAIT: Name = Name::new_inline_ascii(5, b"Clone");

crates/ra_mbe/src/syntax_bridge.rs

@@ -2,7 +2,7 @@
 
 use ra_parser::{FragmentKind, ParseError, TreeSink};
 use ra_syntax::{
-    ast, AstNode, AstToken, NodeOrToken, Parse, SmolStr, SyntaxKind, SyntaxKind::*, SyntaxNode,
+    ast, AstToken, NodeOrToken, Parse, SmolStr, SyntaxKind, SyntaxKind::*, SyntaxNode,
     SyntaxTreeBuilder, TextRange, TextUnit, T,
 };
 use std::iter::successors;
@@ -20,7 +20,7 @@ pub struct TokenMap {
 
 /// Convert the syntax tree (what user has written) to a `TokenTree` (what macro
 /// will consume).
-pub fn ast_to_token_tree(ast: &ast::TokenTree) -> Option<(tt::Subtree, TokenMap)> {
+pub fn ast_to_token_tree(ast: &impl ast::AstNode) -> Option<(tt::Subtree, TokenMap)> {
     syntax_node_to_token_tree(ast.syntax())
 }
 
@@ -208,13 +208,8 @@ impl Convertor {
                     } else if token.kind().is_trivia() {
                         continue;
                     } else if token.kind().is_punct() {
-                        assert!(
+                        // we need to pull apart joined punctuation tokens
-                            token.text().len() == 1,
+                        let last_spacing = match child_iter.peek() {
-                            "Input ast::token punct must be single char."
-                        );
-                        let char = token.text().chars().next().unwrap();
-
-                        let spacing = match child_iter.peek() {
                             Some(NodeOrToken::Token(token)) => {
                                 if token.kind().is_punct() {
                                     tt::Spacing::Joint
@@ -224,8 +219,12 @@ impl Convertor {
                             }
                             _ => tt::Spacing::Alone,
                         };
-
+                        let spacing_iter = std::iter::repeat(tt::Spacing::Joint)
+                            .take(token.text().len() - 1)
+                            .chain(std::iter::once(last_spacing));
+                        for (char, spacing) in token.text().chars().zip(spacing_iter) {
                             token_trees.push(tt::Leaf::from(tt::Punct { char, spacing }).into());
+                        }
                     } else {
                         let child: tt::TokenTree =
                             if token.kind() == T![true] || token.kind() == T![false] {
@@ -389,7 +388,10 @@ mod tests {
     use super::*;
     use crate::tests::{create_rules, expand};
     use ra_parser::TokenSource;
-    use ra_syntax::algo::{insert_children, InsertPosition};
+    use ra_syntax::{
+        algo::{insert_children, InsertPosition},
+        ast::AstNode,
+    };
 
     #[test]
     fn convert_tt_token_source() {
@@ -491,4 +493,12 @@ mod tests {
 
         assert_eq!(tt.delimiter, tt::Delimiter::Brace);
     }
+
+    #[test]
+    fn test_token_tree_multi_char_punct() {
+        let source_file = ast::SourceFile::parse("struct Foo { a: x::Y }").ok().unwrap();
+        let struct_def = source_file.syntax().descendants().find_map(ast::StructDef::cast).unwrap();
+        let tt = ast_to_token_tree(&struct_def).unwrap().0;
+        token_tree_to_syntax_node(&tt, FragmentKind::Item).unwrap();
+    }
 }