10 files changed, 123 insertions, 53 deletions

diff --git a/crates/ra_hir/src/code_model/attrs.rs b/crates/ra_hir/src/code_model/attrs.rs
index 9e304217c..96da8c88c 100644
--- a/crates/ra_hir/src/code_model/attrs.rs
+++ b/crates/ra_hir/src/code_model/attrs.rs
@@ -5,10 +5,9 @@ use crate::{
     Adt, Const, Enum, EnumVariant, FieldSource, Function, HasSource, MacroDef, Module, Static,
     Struct, StructField, Trait, TypeAlias, Union,
 };
-use hir_def::attr::Attr;
+use hir_def::attr::{Attr, Attrs};
 use hir_expand::hygiene::Hygiene;
 use ra_syntax::ast;
-use std::sync::Arc;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub enum AttrDef {
@@ -37,17 +36,17 @@ impl_froms!(
     MacroDef
 );
 
-pub trait Attrs {
-    fn attrs(&self, db: &impl HirDatabase) -> Option<Arc<[Attr]>>;
+pub trait HasAttrs {
+    fn attrs(&self, db: &impl HirDatabase) -> Attrs;
 }
 
-pub(crate) fn attributes_query(
-    db: &(impl DefDatabase + AstDatabase),
-    def: AttrDef,
-) -> Option<Arc<[Attr]>> {
+pub(crate) fn attributes_query(db: &(impl DefDatabase + AstDatabase), def: AttrDef) -> Attrs {
     match def {
         AttrDef::Module(it) => {
-            let src = it.declaration_source(db)?;
+            let src = match it.declaration_source(db) {
+                Some(it) => it,
+                None => return Attrs::default(),
+            };
             let hygiene = Hygiene::new(db, src.file_id);
             Attr::from_attrs_owner(&src.value, &hygiene)
         }
@@ -57,7 +56,7 @@ pub(crate) fn attributes_query(
                 let hygiene = Hygiene::new(db, src.file_id);
                 Attr::from_attrs_owner(&named, &hygiene)
             }
-            FieldSource::Pos(..) => None,
+            FieldSource::Pos(..) => Attrs::default(),
         },
         AttrDef::Adt(it) => match it {
             Adt::Struct(it) => attrs_from_ast(it, db),
@@ -74,7 +73,7 @@ pub(crate) fn attributes_query(
     }
 }
 
-fn attrs_from_ast<T, D>(node: T, db: &D) -> Option<Arc<[Attr]>>
+fn attrs_from_ast<T, D>(node: T, db: &D) -> Attrs
 where
     T: HasSource,
     T::Ast: ast::AttrsOwner,
@@ -85,8 +84,8 @@ where
     Attr::from_attrs_owner(&src.value, &hygiene)
 }
 
-impl<T: Into<AttrDef> + Copy> Attrs for T {
-    fn attrs(&self, db: &impl HirDatabase) -> Option<Arc<[Attr]>> {
+impl<T: Into<AttrDef> + Copy> HasAttrs for T {
+    fn attrs(&self, db: &impl HirDatabase) -> Attrs {
         db.attrs((*self).into())
     }
 }
diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 689874331..1cfcb2fd2 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -2,7 +2,7 @@
 
 use std::sync::Arc;
 
-use hir_def::attr::Attr;
+use hir_def::attr::Attrs;
 use ra_db::salsa;
 use ra_syntax::SmolStr;
 
@@ -57,7 +57,7 @@ pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
     fn documentation(&self, def: crate::DocDef) -> Option<crate::Documentation>;
 
     #[salsa::invoke(crate::code_model::attrs::attributes_query)]
-    fn attrs(&self, def: crate::AttrDef) -> Option<Arc<[Attr]>>;
+    fn attrs(&self, def: crate::AttrDef) -> Attrs;
 }
 
 #[salsa::query_group(HirDatabaseStorage)]
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 8e532c36c..8535629ca 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -51,7 +51,7 @@ mod marks;
 
 pub use crate::{
     code_model::{
-        attrs::{AttrDef, Attrs},
+        attrs::{AttrDef, HasAttrs},
         docs::{DocDef, Docs, Documentation},
         src::{HasBodySource, HasSource},
         Adt, AssocItem, Const, ConstData, Container, Crate, CrateDependency, DefWithBody, Enum,
diff --git a/crates/ra_hir_def/src/attr.rs b/crates/ra_hir_def/src/attr.rs
index 0e961ca12..7a9d0fdf4 100644
--- a/crates/ra_hir_def/src/attr.rs
+++ b/crates/ra_hir_def/src/attr.rs
@@ -1,6 +1,6 @@
 //! A higher level attributes based on TokenTree, with also some shortcuts.
 
-use std::sync::Arc;
+use std::{ops, sync::Arc};
 
 use hir_expand::hygiene::Hygiene;
 use mbe::ast_to_token_tree;
@@ -13,6 +13,28 @@ use tt::Subtree;
 
 use crate::path::Path;
 
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct Attrs {
+    entries: Option<Arc<[Attr]>>,
+}
+
+impl ops::Deref for Attrs {
+    type Target = [Attr];
+
+    fn deref(&self) -> &[Attr] {
+        match &self.entries {
+            Some(it) => &*it,
+            None => &[],
+        }
+    }
+}
+
+impl Attrs {
+    pub fn has_atom(&self, atom: &str) -> bool {
+        self.iter().any(|it| it.is_simple_atom(atom))
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Attr {
     pub(crate) path: Path,
@@ -43,13 +65,15 @@ impl Attr {
         Some(Attr { path, input })
     }
 
-    pub fn from_attrs_owner(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Option<Arc<[Attr]>> {
+    pub fn from_attrs_owner(owner: &dyn AttrsOwner, hygiene: &Hygiene) -> Attrs {
         let mut attrs = owner.attrs().peekable();
-        if attrs.peek().is_none() {
+        let entries = if attrs.peek().is_none() {
             // Avoid heap allocation
-            return None;
-        }
-        Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).collect())
+            None
+        } else {
+            Some(attrs.flat_map(|ast| Attr::from_src(ast, hygiene)).collect())
+        };
+        Attrs { entries }
     }
 
     pub fn is_simple_atom(&self, name: &str) -> bool {
diff --git a/crates/ra_hir_def/src/nameres/collector.rs b/crates/ra_hir_def/src/nameres/collector.rs
index aae3dcadf..7902293e8 100644
--- a/crates/ra_hir_def/src/nameres/collector.rs
+++ b/crates/ra_hir_def/src/nameres/collector.rs
@@ -12,7 +12,7 @@ use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 
 use crate::{
-    attr::Attr,
+    attr::Attrs,
     db::DefDatabase2,
     nameres::{
         diagnostics::DefDiagnostic, mod_resolution::ModDir, path_resolution::ReachedFixedPoint,
@@ -549,7 +549,7 @@ where
         // `#[macro_use] extern crate` is hoisted to imports macros before collecting
         // any other items.
         for item in items {
-            if self.is_cfg_enabled(item.attrs()) {
+            if self.is_cfg_enabled(&item.attrs) {
                 if let raw::RawItemKind::Import(import_id) = item.kind {
                     let import = self.raw_items[import_id].clone();
                     if import.is_extern_crate && import.is_macro_use {
@@ -560,10 +560,10 @@ where
         }
 
         for item in items {
-            if self.is_cfg_enabled(item.attrs()) {
+            if self.is_cfg_enabled(&item.attrs) {
                 match item.kind {
                     raw::RawItemKind::Module(m) => {
-                        self.collect_module(&self.raw_items[m], item.attrs())
+                        self.collect_module(&self.raw_items[m], &item.attrs)
                     }
                     raw::RawItemKind::Import(import_id) => self
                         .def_collector
@@ -585,9 +585,9 @@ where
         }
     }
 
-    fn collect_module(&mut self, module: &raw::ModuleData, attrs: &[Attr]) {
+    fn collect_module(&mut self, module: &raw::ModuleData, attrs: &Attrs) {
         let path_attr = self.path_attr(attrs);
-        let is_macro_use = self.is_macro_use(attrs);
+        let is_macro_use = attrs.has_atom("macro_use");
         match module {
             // inline module, just recurse
             raw::ModuleData::Definition { name, items, ast_id } => {
@@ -779,17 +779,13 @@ where
         }
     }
 
-    fn is_cfg_enabled(&self, attrs: &[Attr]) -> bool {
+    fn is_cfg_enabled(&self, attrs: &Attrs) -> bool {
         attrs.iter().all(|attr| attr.is_cfg_enabled(&self.def_collector.cfg_options) != Some(false))
     }
 
-    fn path_attr<'a>(&self, attrs: &'a [Attr]) -> Option<&'a SmolStr> {
+    fn path_attr<'a>(&self, attrs: &'a Attrs) -> Option<&'a SmolStr> {
         attrs.iter().find_map(|attr| attr.as_path())
     }
-
-    fn is_macro_use<'a>(&self, attrs: &'a [Attr]) -> bool {
-        attrs.iter().any(|attr| attr.is_simple_atom("macro_use"))
-    }
 }
 
 fn is_macro_rules(path: &Path) -> bool {
diff --git a/crates/ra_hir_def/src/nameres/raw.rs b/crates/ra_hir_def/src/nameres/raw.rs
index 7c68fd638..55a9634f8 100644
--- a/crates/ra_hir_def/src/nameres/raw.rs
+++ b/crates/ra_hir_def/src/nameres/raw.rs
@@ -16,7 +16,12 @@ use ra_syntax::{
 };
 use test_utils::tested_by;
 
-use crate::{attr::Attr, db::DefDatabase2, path::Path, FileAstId, HirFileId, ModuleSource, Source};
+use crate::{
+    attr::{Attr, Attrs},
+    db::DefDatabase2,
+    path::Path,
+    FileAstId, HirFileId, ModuleSource, Source,
+};
 
 /// `RawItems` is a set of top-level items in a file (except for impls).
 ///
@@ -129,21 +134,12 @@ impl Index<Impl> for RawItems {
     }
 }
 
-// Avoid heap allocation on items without attributes.
-type Attrs = Option<Arc<[Attr]>>;
-
 #[derive(Debug, PartialEq, Eq, Clone)]
 pub(super) struct RawItem {
-    attrs: Attrs,
+    pub(super) attrs: Attrs,
     pub(super) kind: RawItemKind,
 }
 
-impl RawItem {
-    pub(super) fn attrs(&self) -> &[Attr] {
-        self.attrs.as_ref().map_or(&[], |it| &*it)
-    }
-}
-
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub(super) enum RawItemKind {
     Module(Module),
diff --git a/crates/ra_hir_expand/src/builtin_macro.rs b/crates/ra_hir_expand/src/builtin_macro.rs
index 97fb0cb55..9628666d4 100644
--- a/crates/ra_hir_expand/src/builtin_macro.rs
+++ b/crates/ra_hir_expand/src/builtin_macro.rs
@@ -11,6 +11,7 @@ use crate::quote;
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum BuiltinExpander {
     Line,
+    Stringify,
 }
 
 impl BuiltinExpander {
@@ -22,6 +23,7 @@ impl BuiltinExpander {
     ) -> Result<tt::Subtree, mbe::ExpandError> {
         match self {
             BuiltinExpander::Line => line_expand(db, id, tt),
+            BuiltinExpander::Stringify => stringify_expand(db, id, tt),
         }
     }
 }
@@ -34,6 +36,8 @@ pub fn find_builtin_macro(
     // FIXME: Better registering method
     if ident == &name::LINE_MACRO {
         Some(MacroDefId { krate, ast_id, kind: MacroDefKind::BuiltIn(BuiltinExpander::Line) })
+    } else if ident == &name::STRINGIFY_MACRO {
+        Some(MacroDefId { krate, ast_id, kind: MacroDefKind::BuiltIn(BuiltinExpander::Stringify) })
     } else {
         None
     }
@@ -78,3 +82,26 @@ fn line_expand(
 
     Ok(expanded)
 }
+
+fn stringify_expand(
+    db: &dyn AstDatabase,
+    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_content = {
+        let arg = macro_call.token_tree().ok_or_else(|| mbe::ExpandError::UnexpectedToken)?;
+        let macro_args = arg.syntax().clone();
+        let text = macro_args.text();
+        let without_parens = TextUnit::of_char('(')..text.len() - TextUnit::of_char(')');
+        text.slice(without_parens).to_string()
+    };
+
+    let expanded = quote! {
+        #macro_content
+    };
+
+    Ok(expanded)
+}
diff --git a/crates/ra_hir_expand/src/name.rs b/crates/ra_hir_expand/src/name.rs
index 1bf17d12b..c3f7e77a5 100644
--- a/crates/ra_hir_expand/src/name.rs
+++ b/crates/ra_hir_expand/src/name.rs
@@ -143,3 +143,4 @@ 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");
+pub const STRINGIFY_MACRO: Name = Name::new_inline_ascii(9, b"stringify");
diff --git a/crates/ra_ide_api/src/completion/presentation.rs b/crates/ra_ide_api/src/completion/presentation.rs
index b20329459..bd464d193 100644
--- a/crates/ra_ide_api/src/completion/presentation.rs
+++ b/crates/ra_ide_api/src/completion/presentation.rs
@@ -1,6 +1,6 @@
 //! This modules takes care of rendering various definitions as completion items.
 
-use hir::{db::HirDatabase, Attrs, Docs, HasSource, HirDisplay, ScopeDef, Ty, TypeWalk};
+use hir::{db::HirDatabase, Docs, HasAttrs, HasSource, HirDisplay, ScopeDef, Ty, TypeWalk};
 use join_to_string::join;
 use ra_syntax::ast::NameOwner;
 use test_utils::tested_by;
@@ -285,11 +285,8 @@ impl Completions {
     }
 }
 
-fn is_deprecated(node: impl Attrs, db: &impl HirDatabase) -> bool {
-    match node.attrs(db) {
-        None => false,
-        Some(attrs) => attrs.iter().any(|x| x.is_simple_atom("deprecated")),
-    }
+fn is_deprecated(node: impl HasAttrs, db: &impl HirDatabase) -> bool {
+    node.attrs(db).has_atom("deprecated")
 }
 
 fn has_non_default_type_params(def: hir::GenericDef, db: &db::RootDatabase) -> bool {
diff --git a/crates/ra_ide_api/src/expand_macro.rs b/crates/ra_ide_api/src/expand_macro.rs
index 7dbf33a16..673301b10 100644
--- a/crates/ra_ide_api/src/expand_macro.rs
+++ b/crates/ra_ide_api/src/expand_macro.rs
@@ -40,7 +40,7 @@ fn expand_macro_recur(
     let analyzer = hir::SourceAnalyzer::new(db, source, None);
     let expansion = analyzer.expand(db, macro_call)?;
     let macro_file_id = expansion.file_id();
-    let expanded: SyntaxNode = db.parse_or_expand(macro_file_id)?;
+    let mut expanded: SyntaxNode = db.parse_or_expand(macro_file_id)?;
 
     let children = expanded.descendants().filter_map(ast::MacroCall::cast);
     let mut replaces = FxHashMap::default();
@@ -49,7 +49,14 @@ fn expand_macro_recur(
         let node = hir::Source::new(macro_file_id, &child);
         let new_node = expand_macro_recur(db, source, node)?;
 
-        replaces.insert(child.syntax().clone().into(), new_node.into());
+        // Replace the whole node if it is root
+        // `replace_descendants` will not replace the parent node
+        // but `SyntaxNode::descendants include itself
+        if expanded == *child.syntax() {
+            expanded = new_node;
+        } else {
+            replaces.insert(child.syntax().clone().into(), new_node.into());
+        }
     }
 
     Some(replace_descendants(&expanded, &replaces))
@@ -217,4 +224,27 @@ fn some_thing() -> u32 {
 }
 "###);
     }
+
+    #[test]
+    fn macro_expand_match_ast_inside_let_statement() {
+        let res = check_expand_macro(
+            r#"
+        //- /lib.rs
+        macro_rules! match_ast {
+            (match $node:ident { $($tt:tt)* }) => { match_ast!(match ($node) { $($tt)* }) };        
+            (match ($node:expr) {}) => {{}};
+        }        
+
+        fn main() {        
+            let p = f(|it| {
+                let res = mat<|>ch_ast! { match c {}};
+                Some(res)
+            })?;
+        }
+        "#,
+        );
+
+        assert_eq!(res.name, "match_ast");
+        assert_snapshot!(res.expansion, @r###"{}"###);
+    }
 }