1 files changed, 50 insertions, 16 deletions

diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index b4dafe1d8..5eadee9c2 100644
--- a/crates/ra_hir_expand/src/db.rs
+++ b/crates/ra_hir_expand/src/db.rs
@@ -9,10 +9,37 @@ use ra_prof::profile;
 use ra_syntax::{AstNode, Parse, SyntaxNode};
 
 use crate::{
-    ast_id_map::AstIdMap, HirFileId, HirFileIdRepr, MacroCallId, MacroCallLoc, MacroDefId,
-    MacroFile, MacroFileKind,
+    ast_id_map::AstIdMap, BuiltinExpander, HirFileId, HirFileIdRepr, MacroCallId, MacroCallLoc,
+    MacroDefId, MacroDefKind, MacroFile, MacroFileKind,
 };
 
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub enum TokenExpander {
+    MacroRules(mbe::MacroRules),
+    Builtin(BuiltinExpander),
+}
+
+impl TokenExpander {
+    pub fn expand(
+        &self,
+        db: &dyn AstDatabase,
+        id: MacroCallId,
+        tt: &tt::Subtree,
+    ) -> Result<tt::Subtree, mbe::ExpandError> {
+        match self {
+            TokenExpander::MacroRules(it) => it.expand(tt),
+            TokenExpander::Builtin(it) => it.expand(db, id, tt),
+        }
+    }
+
+    pub fn shift(&self) -> u32 {
+        match self {
+            TokenExpander::MacroRules(it) => it.shift(),
+            TokenExpander::Builtin(_) => 0,
+        }
+    }
+}
+
 // FIXME: rename to ExpandDatabase
 #[salsa::query_group(AstDatabaseStorage)]
 pub trait AstDatabase: SourceDatabase {
@@ -24,7 +51,7 @@ pub trait AstDatabase: SourceDatabase {
     #[salsa::interned]
     fn intern_macro(&self, macro_call: MacroCallLoc) -> MacroCallId;
     fn macro_arg(&self, id: MacroCallId) -> Option<Arc<(tt::Subtree, mbe::TokenMap)>>;
-    fn macro_def(&self, id: MacroDefId) -> Option<Arc<(mbe::MacroRules, mbe::TokenMap)>>;
+    fn macro_def(&self, id: MacroDefId) -> Option<Arc<(TokenExpander, mbe::TokenMap)>>;
     fn parse_macro(
         &self,
         macro_file: MacroFile,
@@ -41,18 +68,25 @@ pub(crate) fn ast_id_map(db: &dyn AstDatabase, file_id: HirFileId) -> Arc<AstIdM
 pub(crate) fn macro_def(
     db: &dyn AstDatabase,
     id: MacroDefId,
-) -> Option<Arc<(mbe::MacroRules, mbe::TokenMap)>> {
-    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);
-        None
-    })?;
-    let rules = MacroRules::parse(&tt).ok().or_else(|| {
-        log::warn!("fail on macro_def parse: {:#?}", tt);
-        None
-    })?;
-    Some(Arc::new((rules, tmap)))
+) -> Option<Arc<(TokenExpander, mbe::TokenMap)>> {
+    match id.kind {
+        MacroDefKind::Declarative => {
+            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);
+                None
+            })?;
+            let rules = MacroRules::parse(&tt).ok().or_else(|| {
+                log::warn!("fail on macro_def parse: {:#?}", tt);
+                None
+            })?;
+            Some(Arc::new((TokenExpander::MacroRules(rules), tmap)))
+        }
+        MacroDefKind::BuiltIn(expander) => {
+            Some(Arc::new((TokenExpander::Builtin(expander.clone()), mbe::TokenMap::default())))
+        }
+    }
 }
 
 pub(crate) fn macro_arg(
@@ -74,7 +108,7 @@ pub(crate) fn macro_expand(
     let macro_arg = db.macro_arg(id).ok_or("Fail to args in to tt::TokenTree")?;
 
     let macro_rules = db.macro_def(loc.def).ok_or("Fail to find macro definition")?;
-    let tt = macro_rules.0.expand(&macro_arg.0).map_err(|err| format!("{:?}", err))?;
+    let tt = macro_rules.0.expand(db, id, &macro_arg.0).map_err(|err| format!("{:?}", err))?;
     // Set a hard limit for the expanded tt
     let count = tt.count();
     if count > 65536 {