Support $crate in item and expr place.

crates/ra_assists/src/assists/auto_import.rs

@@ -512,7 +512,7 @@ pub fn collect_hir_path_segments(path: &hir::Path) -> Option<Vec<SmolStr>> {
         hir::PathKind::Plain => {}
         hir::PathKind::Self_ => ps.push("self".into()),
         hir::PathKind::Super => ps.push("super".into()),
-        hir::PathKind::Type(_) => return None,
+        hir::PathKind::Type(_) | hir::PathKind::DollarCrate(_) => return None,
     }
     for s in path.segments.iter() {
         ps.push(s.name.to_string().into());

crates/ra_hir/src/expr/lower.rs

@@ -272,8 +272,11 @@ where
                 self.alloc_expr(Expr::Match { expr, arms }, syntax_ptr)
             }
             ast::Expr::PathExpr(e) => {
-                let path =
+                let path = e
-                    e.path().and_then(Path::from_ast).map(Expr::Path).unwrap_or(Expr::Missing);
+                    .path()
+                    .and_then(|path| self.parse_path(path))
+                    .map(Expr::Path)
+                    .unwrap_or(Expr::Missing);
                 self.alloc_expr(path, syntax_ptr)
             }
             ast::Expr::ContinueExpr(_e) => {
@@ -295,7 +298,7 @@ where
                 self.alloc_expr(Expr::Return { expr }, syntax_ptr)
             }
             ast::Expr::RecordLit(e) => {
-                let path = e.path().and_then(Path::from_ast);
+                let path = e.path().and_then(|path| self.parse_path(path));
                 let mut field_ptrs = Vec::new();
                 let record_lit = if let Some(nfl) = e.record_field_list() {
                     let fields = nfl
@@ -459,7 +462,7 @@ where
                     .ast_id(&e)
                     .with_file_id(self.current_file_id);
 
-                if let Some(path) = e.path().and_then(Path::from_ast) {
+                if let Some(path) = e.path().and_then(|path| self.parse_path(path)) {
                     if let Some(def) = self.resolver.resolve_path_as_macro(self.db, &path) {
                         let call_id = MacroCallLoc { def: def.id, ast_id }.id(self.db);
                         let file_id = call_id.as_file(MacroFileKind::Expr);
@@ -529,7 +532,7 @@ where
                 Pat::Bind { name, mode: annotation, subpat }
             }
             ast::Pat::TupleStructPat(p) => {
-                let path = p.path().and_then(Path::from_ast);
+                let path = p.path().and_then(|path| self.parse_path(path));
                 let args = p.args().map(|p| self.collect_pat(p)).collect();
                 Pat::TupleStruct { path, args }
             }
@@ -539,7 +542,7 @@ where
                 Pat::Ref { pat, mutability }
             }
             ast::Pat::PathPat(p) => {
-                let path = p.path().and_then(Path::from_ast);
+                let path = p.path().and_then(|path| self.parse_path(path));
                 path.map(Pat::Path).unwrap_or(Pat::Missing)
             }
             ast::Pat::TuplePat(p) => {
@@ -548,7 +551,7 @@ where
             }
             ast::Pat::PlaceholderPat(_) => Pat::Wild,
             ast::Pat::RecordPat(p) => {
-                let path = p.path().and_then(Path::from_ast);
+                let path = p.path().and_then(|path| self.parse_path(path));
                 let record_field_pat_list =
                     p.record_field_pat_list().expect("every struct should have a field list");
                 let mut fields: Vec<_> = record_field_pat_list
@@ -589,6 +592,10 @@ where
             self.missing_pat()
         }
     }
+
+    fn parse_path(&mut self, path: ast::Path) -> Option<Path> {
+        Path::from_src(Source { ast: path, file_id: self.current_file_id }, self.db)
+    }
 }
 
 impl From<ast::BinOp> for BinaryOp {

crates/ra_hir/src/generics.rs

@@ -132,6 +132,7 @@ impl GenericParams {
     fn fill_params(&mut self, params: ast::TypeParamList, start: u32) {
         for (idx, type_param) in params.type_params().enumerate() {
             let name = type_param.name().map_or_else(Name::missing, |it| it.as_name());
+            // FIXME: Use `Path::from_src`
             let default = type_param.default_type().and_then(|t| t.path()).and_then(Path::from_ast);
 
             let param = GenericParam { idx: idx as u32 + start, name: name.clone(), default };

crates/ra_hir/src/ids.rs

@@ -58,6 +58,17 @@ impl HirFileId {
         }
     }
 
+    /// Get the crate which the macro lives in, if it is a macro file.
+    pub(crate) fn macro_crate(self, db: &impl AstDatabase) -> Option<Crate> {
+        match self.0 {
+            HirFileIdRepr::File(_) => None,
+            HirFileIdRepr::Macro(macro_file) => {
+                let loc = macro_file.macro_call_id.loc(db);
+                Some(loc.def.krate)
+            }
+        }
+    }
+
     pub(crate) fn parse_or_expand_query(
         db: &impl AstDatabase,
         file_id: HirFileId,

crates/ra_hir/src/impl_block.rs

@@ -218,7 +218,10 @@ impl ModuleImplBlocks {
                 ast::ItemOrMacro::Macro(macro_call) => {
                     //FIXME: we should really cut down on the boilerplate required to process a macro
                     let ast_id = db.ast_id_map(file_id).ast_id(&macro_call).with_file_id(file_id);
-                    if let Some(path) = macro_call.path().and_then(Path::from_ast) {
+                    if let Some(path) = macro_call
+                        .path()
+                        .and_then(|path| Path::from_src(Source { ast: path, file_id }, db))
+                    {
                         if let Some(def) = self.module.resolver(db).resolve_path_as_macro(db, &path)
                         {
                             let call_id = MacroCallLoc { def: def.id, ast_id }.id(db);

crates/ra_hir/src/marks.rs

@@ -14,4 +14,6 @@ test_utils::marks!(
     macro_rules_from_other_crates_are_visible_with_macro_use
     prelude_is_macro_use
     coerce_merge_fail_fallback
+    macro_dollar_crate_self
+    macro_dollar_crate_other
 );

crates/ra_hir/src/nameres.rs

@@ -332,6 +332,20 @@ impl CrateDefMap {
     ) -> ResolvePathResult {
         let mut segments = path.segments.iter().enumerate();
         let mut curr_per_ns: PerNs = match path.kind {
+            PathKind::DollarCrate(krate) => {
+                if krate == self.krate {
+                    tested_by!(macro_dollar_crate_self);
+                    PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
+                } else {
+                    match krate.root_module(db) {
+                        Some(module) => {
+                            tested_by!(macro_dollar_crate_other);
+                            PerNs::types(module.into())
+                        }
+                        None => return ResolvePathResult::empty(ReachedFixedPoint::No),
+                    }
+                }
+            }
             PathKind::Crate => {
                 PerNs::types(Module { krate: self.krate, module_id: self.root }.into())
             }

crates/ra_hir/src/nameres/raw.rs

@@ -9,7 +9,7 @@ use test_utils::tested_by;
 
 use crate::{
     db::{AstDatabase, DefDatabase},
-    AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path,
+    AsName, AstIdMap, Either, FileAstId, HirFileId, ModuleSource, Name, Path, Source,
 };
 
 /// `RawItems` is a set of top-level items in a file (except for impls).
@@ -71,6 +71,8 @@ impl RawItems {
             raw_items: RawItems::default(),
             source_ast_id_map: db.ast_id_map(file_id),
             source_map: ImportSourceMap::default(),
+            file_id,
+            db,
         };
         if let Some(node) = db.parse_or_expand(file_id) {
             if let Some(source_file) = ast::SourceFile::cast(node.clone()) {
@@ -192,13 +194,15 @@ pub(super) struct MacroData {
     pub(super) export: bool,
 }
 
-struct RawItemsCollector {
+struct RawItemsCollector<DB> {
     raw_items: RawItems,
     source_ast_id_map: Arc<AstIdMap>,
     source_map: ImportSourceMap,
+    file_id: HirFileId,
+    db: DB,
 }
 
-impl RawItemsCollector {
+impl<DB: AstDatabase> RawItemsCollector<&'_ DB> {
     fn process_module(&mut self, current_module: Option<Module>, body: impl ast::ModuleItemOwner) {
         for item_or_macro in body.items_with_macros() {
             match item_or_macro {
@@ -300,17 +304,21 @@ impl RawItemsCollector {
     fn add_use_item(&mut self, current_module: Option<Module>, use_item: ast::UseItem) {
         let is_prelude = use_item.has_atom_attr("prelude_import");
 
-        Path::expand_use_item(&use_item, |path, use_tree, is_glob, alias| {
+        Path::expand_use_item(
-            let import_data = ImportData {
+            Source { ast: use_item, file_id: self.file_id },
-                path,
+            self.db,
-                alias,
+            |path, use_tree, is_glob, alias| {
-                is_glob,
+                let import_data = ImportData {
-                is_prelude,
+                    path,
-                is_extern_crate: false,
+                    alias,
-                is_macro_use: false,
+                    is_glob,
-            };
+                    is_prelude,
-            self.push_import(current_module, import_data, Either::A(AstPtr::new(use_tree)));
+                    is_extern_crate: false,
-        })
+                    is_macro_use: false,
+                };
+                self.push_import(current_module, import_data, Either::A(AstPtr::new(use_tree)));
+            },
+        )
     }
 
     fn add_extern_crate_item(
@@ -335,7 +343,10 @@ impl RawItemsCollector {
     }
 
     fn add_macro(&mut self, current_module: Option<Module>, m: ast::MacroCall) {
-        let path = match m.path().and_then(Path::from_ast) {
+        let path = match m
+            .path()
+            .and_then(|path| Path::from_src(Source { ast: path, file_id: self.file_id }, self.db))
+        {
             Some(it) => it,
             _ => return,
         };

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

@@ -515,3 +515,108 @@ fn path_qualified_macros() {
         ⋮not_found: _
     "###);
 }
+
+#[test]
+fn macro_dollar_crate_is_correct_in_item() {
+    covers!(macro_dollar_crate_self);
+    covers!(macro_dollar_crate_other);
+    let map = def_map_with_crate_graph(
+        "
+        //- /main.rs
+        #[macro_use]
+        extern crate foo;
+
+        #[macro_use]
+        mod m {
+            macro_rules! current {
+                () => {
+                    use $crate::Foo as FooSelf;
+                }
+            }
+        }
+
+        struct Foo;
+
+        current!();
+        not_current1!();
+        foo::not_current2!();
+
+        //- /lib.rs
+        mod m {
+            #[macro_export]
+            macro_rules! not_current1 {
+                () => {
+                    use $crate::Bar;
+                }
+            }
+        }
+
+        #[macro_export]
+        macro_rules! not_current2 {
+            () => {
+                use $crate::Baz;
+            }
+        }
+
+        struct Bar;
+        struct Baz;
+        ",
+        crate_graph! {
+            "main": ("/main.rs", ["foo"]),
+            "foo": ("/lib.rs", []),
+        },
+    );
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮Bar: t v
+        ⋮Baz: t v
+        ⋮Foo: t v
+        ⋮FooSelf: t v
+        ⋮foo: t
+        ⋮m: t
+        ⋮
+        ⋮crate::m
+    "###);
+}
+
+#[test]
+fn macro_dollar_crate_is_correct_in_indirect_deps() {
+    covers!(macro_dollar_crate_other);
+    // From std
+    let map = def_map_with_crate_graph(
+        r#"
+        //- /main.rs
+        foo!();
+
+        //- /std.rs
+        #[prelude_import]
+        use self::prelude::*;
+
+        pub use core::foo;
+
+        mod prelude {}
+
+        #[macro_use]
+        mod std_macros;
+
+        //- /core.rs
+        #[macro_export]
+        macro_rules! foo {
+            () => {
+                use $crate::bar;
+            }
+        }
+
+        pub struct bar;
+        "#,
+        crate_graph! {
+            "main": ("/main.rs", ["std"]),
+            "std": ("/std.rs", ["core"]),
+            "core": ("/core.rs", []),
+        },
+    );
+    assert_snapshot!(map, @r###"
+        ⋮crate
+        ⋮bar: t v
+    "###);
+}

crates/ra_hir/src/path.rs

@@ -5,7 +5,7 @@ use ra_syntax::{
     AstNode,
 };
 
-use crate::{name, type_ref::TypeRef, AsName, Name};
+use crate::{db::AstDatabase, name, type_ref::TypeRef, AsName, Crate, Name, Source};
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct Path {
@@ -52,16 +52,19 @@ pub enum PathKind {
     Abs,
     // Type based path like `<T>::foo`
     Type(Box<TypeRef>),
+    // `$crate` from macro expansion
+    DollarCrate(Crate),
 }
 
 impl Path {
     /// Calls `cb` with all paths, represented by this use item.
     pub fn expand_use_item(
-        item: &ast::UseItem,
+        item_src: Source<ast::UseItem>,
+        db: &impl AstDatabase,
         mut cb: impl FnMut(Path, &ast::UseTree, bool, Option<Name>),
     ) {
-        if let Some(tree) = item.use_tree() {
+        if let Some(tree) = item_src.ast.use_tree() {
-            expand_use_tree(None, tree, &mut cb);
+            expand_use_tree(None, tree, &|| item_src.file_id.macro_crate(db), &mut cb);
         }
     }
 
@@ -76,7 +79,19 @@ impl Path {
     }
 
     /// Converts an `ast::Path` to `Path`. Works with use trees.
-    pub fn from_ast(mut path: ast::Path) -> Option<Path> {
+    /// DEPRECATED: It does not handle `$crate` from macro call.
+    pub fn from_ast(path: ast::Path) -> Option<Path> {
+        Path::parse(path, &|| None)
+    }
+
+    /// Converts an `ast::Path` to `Path`. Works with use trees.
+    /// It correctly handles `$crate` based path from macro call.
+    pub fn from_src(source: Source<ast::Path>, db: &impl AstDatabase) -> Option<Path> {
+        let file_id = source.file_id;
+        Path::parse(source.ast, &|| file_id.macro_crate(db))
+    }
+
+    fn parse(mut path: ast::Path, macro_crate: &impl Fn() -> Option<Crate>) -> Option<Path> {
         let mut kind = PathKind::Plain;
         let mut segments = Vec::new();
         loop {
@@ -88,6 +103,13 @@ impl Path {
 
             match segment.kind()? {
                 ast::PathSegmentKind::Name(name) => {
+                    if name.text() == "$crate" {
+                        if let Some(macro_crate) = macro_crate() {
+                            kind = PathKind::DollarCrate(macro_crate);
+                            break;
+                        }
+                    }
+
                     let args = segment
                         .type_arg_list()
                         .and_then(GenericArgs::from_ast)
@@ -113,7 +135,7 @@ impl Path {
                         }
                         // <T as Trait<A>>::Foo desugars to Trait<Self=T, A>::Foo
                         Some(trait_ref) => {
-                            let path = Path::from_ast(trait_ref.path()?)?;
+                            let path = Path::parse(trait_ref.path()?, macro_crate)?;
                             kind = path.kind;
                             let mut prefix_segments = path.segments;
                             prefix_segments.reverse();
@@ -264,6 +286,7 @@ impl From<Name> for Path {
 fn expand_use_tree(
     prefix: Option<Path>,
     tree: ast::UseTree,
+    macro_crate: &impl Fn() -> Option<Crate>,
     cb: &mut impl FnMut(Path, &ast::UseTree, bool, Option<Name>),
 ) {
     if let Some(use_tree_list) = tree.use_tree_list() {
@@ -272,13 +295,13 @@ fn expand_use_tree(
             None => prefix,
             // E.g. `use something::{inner}` (prefix is `None`, path is `something`)
             // or `use something::{path::{inner::{innerer}}}` (prefix is `something::path`, path is `inner`)
-            Some(path) => match convert_path(prefix, path) {
+            Some(path) => match convert_path(prefix, path, macro_crate) {
                 Some(it) => Some(it),
                 None => return, // FIXME: report errors somewhere
             },
         };
         for child_tree in use_tree_list.use_trees() {
-            expand_use_tree(prefix.clone(), child_tree, cb);
+            expand_use_tree(prefix.clone(), child_tree, macro_crate, cb);
         }
     } else {
         let alias = tree.alias().and_then(|a| a.name()).map(|a| a.as_name());
@@ -295,7 +318,7 @@ fn expand_use_tree(
                     }
                 }
             }
-            if let Some(path) = convert_path(prefix, ast_path) {
+            if let Some(path) = convert_path(prefix, ast_path, macro_crate) {
                 let is_glob = tree.has_star();
                 cb(path, &tree, is_glob, alias)
             }
@@ -305,12 +328,29 @@ fn expand_use_tree(
     }
 }
 
-fn convert_path(prefix: Option<Path>, path: ast::Path) -> Option<Path> {
+fn convert_path(
-    let prefix =
+    prefix: Option<Path>,
-        if let Some(qual) = path.qualifier() { Some(convert_path(prefix, qual)?) } else { prefix };
+    path: ast::Path,
+    macro_crate: &impl Fn() -> Option<Crate>,
+) -> Option<Path> {
+    let prefix = if let Some(qual) = path.qualifier() {
+        Some(convert_path(prefix, qual, macro_crate)?)
+    } else {
+        prefix
+    };
+
     let segment = path.segment()?;
     let res = match segment.kind()? {
         ast::PathSegmentKind::Name(name) => {
+            if name.text() == "$crate" {
+                if let Some(krate) = macro_crate() {
+                    return Some(Path::from_simple_segments(
+                        PathKind::DollarCrate(krate),
+                        iter::empty(),
+                    ));
+                }
+            }
+
             // no type args in use
             let mut res = prefix
                 .unwrap_or_else(|| Path { kind: PathKind::Plain, segments: Vec::with_capacity(1) });

crates/ra_hir/src/source_binder.rs

@@ -203,6 +203,7 @@ impl SourceAnalyzer {
         db: &impl HirDatabase,
         macro_call: &ast::MacroCall,
     ) -> Option<MacroDef> {
+        // This must be a normal source file rather than macro file.
         let path = macro_call.path().and_then(Path::from_ast)?;
         self.resolver.resolve_path_as_macro(db, &path)
     }
@@ -261,6 +262,7 @@ impl SourceAnalyzer {
                 return Some(PathResolution::AssocItem(assoc));
             }
         }
+        // This must be a normal source file rather than macro file.
         let hir_path = crate::Path::from_ast(path.clone())?;
         self.resolve_hir_path(db, &hir_path)
     }

crates/ra_hir/src/ty/tests.rs

@@ -3130,6 +3130,39 @@ fn test() { S.foo()<|>; }
     assert_eq!(t, "u128");
 }
 
+#[test]
+fn infer_macro_with_dollar_crate_is_correct_in_expr() {
+    covers!(macro_dollar_crate_other);
+    let (mut db, pos) = MockDatabase::with_position(
+        r#"
+//- /main.rs
+fn test() {
+    let x = (foo::foo!(1), foo::foo!(2));
+    x<|>;
+}
+
+//- /lib.rs
+#[macro_export]
+macro_rules! foo {
+    (1) => { $crate::bar!() };
+    (2) => { 1 + $crate::baz() };
+}
+
+#[macro_export]
+macro_rules! bar {
+    () => { 42 }
+}
+
+pub fn baz() -> usize { 31usize }
+"#,
+    );
+    db.set_crate_graph_from_fixture(crate_graph! {
+        "main": ("/main.rs", ["foo"]),
+        "foo": ("/lib.rs", []),
+    });
+    assert_eq!("(i32, usize)", type_at_pos(&db, pos));
+}
+
 #[ignore]
 #[test]
 fn method_resolution_trait_before_autoref() {

crates/ra_hir/src/type_ref.rs

@@ -72,6 +72,7 @@ impl TypeRef {
             }
             ast::TypeRef::NeverType(..) => TypeRef::Never,
             ast::TypeRef::PathType(inner) => {
+                // FIXME: Use `Path::from_src`
                 inner.path().and_then(Path::from_ast).map(TypeRef::Path).unwrap_or(TypeRef::Error)
             }
             ast::TypeRef::PointerType(inner) => {
@@ -141,6 +142,7 @@ impl TypeBound {
                     Some(p) => p,
                     None => return TypeBound::Error,
                 };
+                // FIXME: Use `Path::from_src`
                 let path = match Path::from_ast(path) {
                     Some(p) => p,
                     None => return TypeBound::Error,

crates/ra_mbe/src/mbe_expander/transcriber.rs

@@ -86,7 +86,7 @@ fn expand_subtree(ctx: &mut ExpandCtx, template: &tt::Subtree) -> Result<tt::Sub
 
 fn expand_var(ctx: &mut ExpandCtx, v: &SmolStr) -> Result<Fragment, ExpandError> {
     let res = if v == "crate" {
-        // FIXME: Properly handle $crate token
+        // We simply produce identifier `$crate` here. And it will be resolved when lowering ast to Path.
         let tt =
             tt::Leaf::from(tt::Ident { text: "$crate".into(), id: tt::TokenId::unspecified() })
                 .into();