4 files changed, 62 insertions, 8 deletions

diff --git a/crates/ra_assists/src/assists/add_explicit_type.rs b/crates/ra_assists/src/assists/add_explicit_type.rs
index eeb4ff39f..2c602a79e 100644
--- a/crates/ra_assists/src/assists/add_explicit_type.rs
+++ b/crates/ra_assists/src/assists/add_explicit_type.rs
@@ -74,6 +74,24 @@ mod tests {
     }
 
     #[test]
+    fn add_explicit_type_works_for_macro_call() {
+        check_assist(
+            add_explicit_type,
+            "macro_rules! v { () => {0u64} } fn f() { let a<|> = v!(); }",
+            "macro_rules! v { () => {0u64} } fn f() { let a<|>: u64 = v!(); }",
+        );
+    }
+
+    #[test]
+    fn add_explicit_type_works_for_macro_call_recursive() {
+        check_assist(
+            add_explicit_type,
+            "macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|> = v!(); }",
+            "macro_rules! u { () => {0u64} } macro_rules! v { () => {u!()} } fn f() { let a<|>: u64 = v!(); }",
+        );
+    }
+
+    #[test]
     fn add_explicit_type_not_applicable_if_ty_not_inferred() {
         check_assist_not_applicable(add_explicit_type, "fn f() { let a<|> = None; }");
     }
diff --git a/crates/ra_hir/src/source_binder.rs b/crates/ra_hir/src/source_binder.rs
index 85b378483..2c422af8b 100644
--- a/crates/ra_hir/src/source_binder.rs
+++ b/crates/ra_hir/src/source_binder.rs
@@ -215,8 +215,32 @@ impl SourceAnalyzer {
         self.body_source_map.as_ref()?.node_pat(src)
     }
 
+    fn expand_expr(
+        &self,
+        db: &impl HirDatabase,
+        expr: InFile<&ast::Expr>,
+    ) -> Option<InFile<ast::Expr>> {
+        let macro_call = ast::MacroCall::cast(expr.value.syntax().clone())?;
+        let macro_file =
+            self.body_source_map.as_ref()?.node_macro_file(expr.with_value(&macro_call))?;
+        let expanded = db.parse_or_expand(macro_file)?;
+        let kind = expanded.kind();
+        let expr = InFile::new(macro_file, ast::Expr::cast(expanded)?);
+
+        if ast::MacroCall::can_cast(kind) {
+            self.expand_expr(db, expr.as_ref())
+        } else {
+            Some(expr)
+        }
+    }
+
     pub fn type_of(&self, db: &impl HirDatabase, expr: &ast::Expr) -> Option<Type> {
-        let expr_id = self.expr_id(expr)?;
+        let expr_id = if let Some(expr) = self.expand_expr(db, InFile::new(self.file_id, expr)) {
+            self.body_source_map.as_ref()?.node_expr(expr.as_ref())?
+        } else {
+            self.expr_id(expr)?
+        };
+
         let ty = self.infer.as_ref()?[expr_id].clone();
         let environment = TraitEnvironment::lower(db, &self.resolver);
         Some(Type { krate: self.resolver.krate()?, ty: InEnvironment { value: ty, environment } })
diff --git a/crates/ra_hir_def/src/body.rs b/crates/ra_hir_def/src/body.rs
index d3e4c50ae..142c52d35 100644
--- a/crates/ra_hir_def/src/body.rs
+++ b/crates/ra_hir_def/src/body.rs
@@ -163,6 +163,7 @@ pub struct BodySourceMap {
     pat_map: FxHashMap<PatSource, PatId>,
     pat_map_back: ArenaMap<PatId, PatSource>,
     field_map: FxHashMap<(ExprId, usize), AstPtr<ast::RecordField>>,
+    expansions: FxHashMap<InFile<AstPtr<ast::MacroCall>>, HirFileId>,
 }
 
 impl Body {
@@ -237,6 +238,11 @@ impl BodySourceMap {
         self.expr_map.get(&src).cloned()
     }
 
+    pub fn node_macro_file(&self, node: InFile<&ast::MacroCall>) -> Option<HirFileId> {
+        let src = node.map(|it| AstPtr::new(it));
+        self.expansions.get(&src).cloned()
+    }
+
     pub fn field_init_shorthand_expr(&self, node: InFile<&ast::RecordField>) -> Option<ExprId> {
         let src = node.map(|it| Either::Right(AstPtr::new(it)));
         self.expr_map.get(&src).cloned()
diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index fc3a028e0..e656f9a41 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -446,14 +446,20 @@ where
                 }
             }
             // FIXME expand to statements in statement position
-            ast::Expr::MacroCall(e) => match self.expander.enter_expand(self.db, e) {
-                Some((mark, expansion)) => {
-                    let id = self.collect_expr(expansion);
-                    self.expander.exit(self.db, mark);
-                    id
+            ast::Expr::MacroCall(e) => {
+                let macro_call = self.expander.to_source(AstPtr::new(&e));
+                match self.expander.enter_expand(self.db, e.clone()) {
+                    Some((mark, expansion)) => {
+                        self.source_map
+                            .expansions
+                            .insert(macro_call, self.expander.current_file_id);
+                        let id = self.collect_expr(expansion);
+                        self.expander.exit(self.db, mark);
+                        id
+                    }
+                    None => self.alloc_expr(Expr::Missing, syntax_ptr),
                 }
-                None => self.alloc_expr(Expr::Missing, syntax_ptr),
-            },
+            }
 
             // FIXME implement HIR for these:
             ast::Expr::Label(_e) => self.alloc_expr(Expr::Missing, syntax_ptr),