From 689e147c9dc416027fd36e94673431533df545f9 Mon Sep 17 00:00:00 2001
From: Jonas Schievink <jonas.schievink@ferrous-systems.com>
Date: Tue, 23 Jun 2020 13:46:38 +0200
Subject: Collect inner items in expression macros

---
 crates/ra_hir_def/src/body/lower.rs      |  4 +++-
 crates/ra_hir_def/src/body/scope.rs      | 20 ++++++++++++++++++++
 crates/ra_hir_def/src/item_tree.rs       | 27 +++++++++++++++------------
 crates/ra_hir_def/src/item_tree/lower.rs |  7 ++++++-
 4 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/crates/ra_hir_def/src/body/lower.rs b/crates/ra_hir_def/src/body/lower.rs
index e7cf80676..bbde0b802 100644
--- a/crates/ra_hir_def/src/body/lower.rs
+++ b/crates/ra_hir_def/src/body/lower.rs
@@ -564,12 +564,14 @@ impl ExprCollector<'_> {
             });
         let tree = &self.item_trees[index].1;
 
+        // FIXME: This probably breaks with `use` items, since they produce multiple item tree nodes
+
         // Root file (non-macro).
         tree.all_inner_items()
             .chain(tree.top_level_items().iter().copied())
             .filter_map(|mod_item| mod_item.downcast::<S>())
             .find(|tree_id| tree[*tree_id].ast_id().upcast() == id.value)
-            .unwrap()
+            .unwrap_or_else(|| panic!("couldn't find inner item for {:?}", id))
     }
 
     fn collect_expr_opt(&mut self, expr: Option<ast::Expr>) -> ExprId {
diff --git a/crates/ra_hir_def/src/body/scope.rs b/crates/ra_hir_def/src/body/scope.rs
index 0b74199d9..81397b063 100644
--- a/crates/ra_hir_def/src/body/scope.rs
+++ b/crates/ra_hir_def/src/body/scope.rs
@@ -317,6 +317,26 @@ fn foo() {
         );
     }
 
+    #[test]
+    fn macro_inner_item() {
+        do_check(
+            r"
+            macro_rules! mac {
+                () => {{
+                    fn inner() {}
+                    inner();
+                }};
+            }
+
+            fn foo() {
+                mac!();
+                <|>
+            }
+        ",
+            &[],
+        );
+    }
+
     fn do_check_local_name(ra_fixture: &str, expected_offset: u32) {
         let (db, position) = TestDB::with_position(ra_fixture);
         let file_id = position.file_id;
diff --git a/crates/ra_hir_def/src/item_tree.rs b/crates/ra_hir_def/src/item_tree.rs
index efcb5dc60..a1a78fc5c 100644
--- a/crates/ra_hir_def/src/item_tree.rs
+++ b/crates/ra_hir_def/src/item_tree.rs
@@ -12,7 +12,7 @@ use std::{
     sync::Arc,
 };
 
-use ast::{AstNode, AttrsOwner, ModuleItemOwner, NameOwner, StructKind, TypeAscriptionOwner};
+use ast::{AstNode, AttrsOwner, NameOwner, StructKind, TypeAscriptionOwner};
 use either::Either;
 use hir_expand::{
     ast_id_map::FileAstId,
@@ -73,25 +73,28 @@ impl ItemTree {
         };
 
         let hygiene = Hygiene::new(db.upcast(), file_id);
+        let ctx = lower::Ctx::new(db, hygiene.clone(), file_id);
         let mut top_attrs = None;
-        let (macro_storage, file_storage);
-        let item_owner = match_ast! {
+        let mut item_tree = match_ast! {
             match syntax {
-                ast::MacroItems(items) => {
-                    macro_storage = items;
-                    &macro_storage as &dyn ModuleItemOwner
-                },
                 ast::SourceFile(file) => {
                     top_attrs = Some(Attrs::new(&file, &hygiene));
-                    file_storage = file;
-                    &file_storage
+                    ctx.lower_module_items(&file)
+                },
+                ast::MacroItems(items) => {
+                    ctx.lower_module_items(&items)
+                },
+                // Macros can expand to expressions. We return an empty item tree in this case, but
+                // still need to collect inner items.
+                ast::Expr(e) => {
+                    ctx.lower_inner_items(e.syntax())
+                },
+                _ => {
+                    panic!("cannot create item tree from {:?}", syntax);
                 },
-                _ => return Arc::new(Self::empty(file_id)),
             }
         };
 
-        let ctx = lower::Ctx::new(db, hygiene, file_id);
-        let mut item_tree = ctx.lower(item_owner);
         item_tree.top_attrs = top_attrs.unwrap_or_default();
         Arc::new(item_tree)
     }
diff --git a/crates/ra_hir_def/src/item_tree/lower.rs b/crates/ra_hir_def/src/item_tree/lower.rs
index 841c7a852..3bb437e81 100644
--- a/crates/ra_hir_def/src/item_tree/lower.rs
+++ b/crates/ra_hir_def/src/item_tree/lower.rs
@@ -52,7 +52,7 @@ impl Ctx {
         }
     }
 
-    pub(super) fn lower(mut self, item_owner: &dyn ModuleItemOwner) -> ItemTree {
+    pub(super) fn lower_module_items(mut self, item_owner: &dyn ModuleItemOwner) -> ItemTree {
         self.tree.top_level = item_owner
             .items()
             .flat_map(|item| self.lower_mod_item(&item, false))
@@ -61,6 +61,11 @@ impl Ctx {
         self.tree
     }
 
+    pub(super) fn lower_inner_items(mut self, within: &SyntaxNode) -> ItemTree {
+        self.collect_inner_items(within);
+        self.tree
+    }
+
     fn lower_mod_item(&mut self, item: &ast::ModuleItem, inner: bool) -> Option<ModItems> {
         assert!(inner || self.inner_items.is_empty());
 
-- 
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