5 files changed, 109 insertions, 22 deletions

diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
new file mode 100644
index 000000000..dca2f17ef
--- /dev/null
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -0,0 +1,26 @@
+//! Builtin macro
+use crate::{ast, name, AstId, BuiltinMacro, CrateId, MacroDefId};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum BuiltinExpander {
+    Line
+}
+
+impl BuiltinExpander {
+    pub fn expand(&self, _tt: &tt::Subtree) -> Result<tt::Subtree, mbe::ExpandError> {
+        Err(mbe::ExpandError::UnexpectedToken)
+    }
+}
+
+pub fn find_builtin_macro(
+    ident: &name::Name,
+    krate: CrateId,
+    ast_id: AstId<ast::MacroCall>,
+) -> Option<MacroDefId> {
+    // FIXME: Better registering method
+    if ident == &name::LINE {
+        Some(MacroDefId::BuiltinMacro(BuiltinMacro { expander: BuiltinExpander::Line, krate, ast_id }))
+    } else {
+        None
+    }
+}
diff --git a/crates/ra_hir_expand/src/db.rs b/crates/ra_hir_expand/src/db.rs
index b4dafe1d8..343c9e6bf 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, 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(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 {
+        MacroDefId::DeclarativeMacro(it) => {
+            let macro_call = it.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)))
+        }
+        MacroDefId::BuiltinMacro(it) => {
+            Some(Arc::new((TokenExpander::Builtin(it.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 {
diff --git a/crates/ra_hir_expand/src/hygiene.rs b/crates/ra_hir_expand/src/hygiene.rs
index 77428ec99..6b682d3ab 100644
--- a/crates/ra_hir_expand/src/hygiene.rs
+++ b/crates/ra_hir_expand/src/hygiene.rs
@@ -9,7 +9,7 @@ use crate::{
     db::AstDatabase,
     either::Either,
     name::{AsName, Name},
-    HirFileId, HirFileIdRepr,
+    HirFileId, HirFileIdRepr, MacroDefId,
 };
 
 #[derive(Debug)]
@@ -24,7 +24,10 @@ impl Hygiene {
             HirFileIdRepr::FileId(_) => None,
             HirFileIdRepr::MacroFile(macro_file) => {
                 let loc = db.lookup_intern_macro(macro_file.macro_call_id);
-                Some(loc.def.krate)
+                match loc.def {
+                    MacroDefId::DeclarativeMacro(it) => Some(it.krate),
+                    MacroDefId::BuiltinMacro(_) => None,
+                }
             }
         };
         Hygiene { def_crate }
diff --git a/crates/ra_hir_expand/src/lib.rs b/crates/ra_hir_expand/src/lib.rs
index 151d1d785..6b71738ee 100644
--- a/crates/ra_hir_expand/src/lib.rs
+++ b/crates/ra_hir_expand/src/lib.rs
@@ -10,6 +10,7 @@ pub mod either;
 pub mod name;
 pub mod hygiene;
 pub mod diagnostics;
+pub mod builtin_macro;
 
 use std::hash::{Hash, Hasher};
 use std::sync::Arc;
@@ -21,6 +22,7 @@ use ra_syntax::{
 };
 
 use crate::ast_id_map::FileAstId;
+use crate::builtin_macro::BuiltinExpander;
 
 /// Input to the analyzer is a set of files, where each file is identified by
 /// `FileId` and contains source code. However, another source of source code in
@@ -75,9 +77,15 @@ impl HirFileId {
             HirFileIdRepr::MacroFile(macro_file) => {
                 let loc: MacroCallLoc = db.lookup_intern_macro(macro_file.macro_call_id);
 
+                // FIXME: Do we support expansion information in builtin macro?
+                let macro_decl = match loc.def {
+                    MacroDefId::DeclarativeMacro(it) => (it),
+                    MacroDefId::BuiltinMacro(_) => return None,
+                };
+
                 let arg_start = loc.ast_id.to_node(db).token_tree()?.syntax().text_range().start();
                 let def_start =
-                    loc.def.ast_id.to_node(db).token_tree()?.syntax().text_range().start();
+                    macro_decl.ast_id.to_node(db).token_tree()?.syntax().text_range().start();
 
                 let macro_def = db.macro_def(loc.def)?;
                 let shift = macro_def.0.shift();
@@ -85,7 +93,7 @@ impl HirFileId {
                 let macro_arg = db.macro_arg(macro_file.macro_call_id)?;
 
                 let arg_start = (loc.ast_id.file_id, arg_start);
-                let def_start = (loc.def.ast_id.file_id, def_start);
+                let def_start = (macro_decl.ast_id.file_id, def_start);
 
                 Some(ExpansionInfo { arg_start, def_start, macro_arg, macro_def, exp_map, shift })
             }
@@ -119,9 +127,22 @@ impl salsa::InternKey for MacroCallId {
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct MacroDefId {
+pub enum MacroDefId {
+    DeclarativeMacro(DeclarativeMacro),
+    BuiltinMacro(BuiltinMacro),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct DeclarativeMacro {
+    pub krate: CrateId,
+    pub ast_id: AstId<ast::MacroCall>,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct BuiltinMacro {
     pub krate: CrateId,
     pub ast_id: AstId<ast::MacroCall>,
+    pub expander: BuiltinExpander,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -144,7 +165,7 @@ pub struct ExpansionInfo {
     pub(crate) def_start: (HirFileId, TextUnit),
     pub(crate) shift: u32,
 
-    pub(crate) macro_def: Arc<(mbe::MacroRules, mbe::TokenMap)>,
+    pub(crate) macro_def: Arc<(db::TokenExpander, mbe::TokenMap)>,
     pub(crate) macro_arg: Arc<(tt::Subtree, mbe::TokenMap)>,
     pub(crate) exp_map: Arc<mbe::RevTokenMap>,
 }
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index 720896ee8..1bf17d12b 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -140,3 +140,6 @@ pub const RESULT_TYPE: Name = Name::new_inline_ascii(6, b"Result");
 pub const OUTPUT_TYPE: Name = Name::new_inline_ascii(6, b"Output");
 pub const TARGET_TYPE: Name = Name::new_inline_ascii(6, b"Target");
 pub const BOX_TYPE: Name = Name::new_inline_ascii(3, b"Box");
+
+// Builtin Macros
+pub const LINE_MACRO: Name = Name::new_inline_ascii(4, b"line");