Fix visibility of items in block modules

Author: jonas-schievink

crates/hir_def/src/lib.rs

@@ -108,6 +108,18 @@ impl ModuleId {
     pub fn containing_module(&self, db: &dyn db::DefDatabase) -> Option<ModuleId> {
         self.def_map(db).containing_module(self.local_id)
     }
+
+    /// Returns `true` if this module represents a block expression.
+    ///
+    /// Returns `false` if this module is a submodule *inside* a block expression
+    /// (eg. `m` in `{ mod m {} }`).
+    pub fn is_block_root(&self, db: &dyn db::DefDatabase) -> bool {
+        if self.block.is_none() {
+            return false;
+        }
+
+        self.def_map(db)[self.local_id].parent.is_none()
+    }
 }
 
 /// An ID of a module, **local** to a specific crate

crates/hir_def/src/visibility.rs

@@ -123,11 +123,19 @@ impl Visibility {
         def_map: &DefMap,
         mut from_module: crate::LocalModuleId,
     ) -> bool {
-        let to_module = match self {
+        let mut to_module = match self {
             Visibility::Module(m) => m,
             Visibility::Public => return true,
         };
 
+        // `to_module` might be the root module of a block expression. Those have the same
+        // visibility as the containing module (even though no items are directly nameable from
+        // there, getting this right is important for method resolution).
+        // In that case, we adjust the visibility of `to_module` to point to the containing module.
+        if to_module.is_block_root(db) {
+            to_module = to_module.containing_module(db).unwrap();
+        }
+
         // from_module needs to be a descendant of to_module
         let mut def_map = def_map;
         let mut parent_arc;