2 files changed, 104 insertions, 1 deletions

diff --git a/crates/ra_analysis/src/db.rs b/crates/ra_analysis/src/db.rs
index 887d687ea..7c28c9a2b 100644
--- a/crates/ra_analysis/src/db.rs
+++ b/crates/ra_analysis/src/db.rs
@@ -1,5 +1,6 @@
 use std::sync::Arc;
 
+use parking_lot::Mutex;
 use ra_editor::LineIndex;
 use ra_syntax::{SourceFileNode, SyntaxNode};
 use salsa::{self, Database};
@@ -18,6 +19,11 @@ use crate::{
 
 #[derive(Debug)]
 pub(crate) struct RootDatabase {
+    #[cfg(test)]
+    events: Mutex<Option<Vec<salsa::Event<RootDatabase>>>>,
+    #[cfg(not(test))]
+    events: (),
+
     runtime: salsa::Runtime<RootDatabase>,
     id_maps: IdMaps,
 }
@@ -26,11 +32,22 @@ impl salsa::Database for RootDatabase {
     fn salsa_runtime(&self) -> &salsa::Runtime<RootDatabase> {
         &self.runtime
     }
+
+    fn salsa_event(&self, event: impl Fn() -> salsa::Event<RootDatabase>) {
+        #[cfg(test)]
+        {
+            let mut events = self.events.lock();
+            if let Some(events) = &mut *events {
+                events.push(event());
+            }
+        }
+    }
 }
 
 impl Default for RootDatabase {
     fn default() -> RootDatabase {
         let mut db = RootDatabase {
+            events: Default::default(),
             runtime: salsa::Runtime::default(),
             id_maps: IdMaps::default(),
         };
@@ -55,6 +72,7 @@ pub(crate) fn check_canceled(db: &impl salsa::Database) -> Cancelable<()> {
 impl salsa::ParallelDatabase for RootDatabase {
     fn snapshot(&self) -> salsa::Snapshot<RootDatabase> {
         salsa::Snapshot::new(RootDatabase {
+            events: Default::default(),
             runtime: self.runtime.snapshot(self),
             id_maps: self.id_maps.clone(),
         })
@@ -67,6 +85,29 @@ impl IdDatabase for RootDatabase {
     }
 }
 
+#[cfg(test)]
+impl RootDatabase {
+    pub(crate) fn log(&self, f: impl FnOnce()) -> Vec<salsa::Event<RootDatabase>> {
+        *self.events.lock() = Some(Vec::new());
+        f();
+        let events = self.events.lock().take().unwrap();
+        events
+    }
+
+    pub(crate) fn log_executed(&self, f: impl FnOnce()) -> Vec<String> {
+        let events = self.log(f);
+        events
+            .into_iter()
+            .filter_map(|e| match e.kind {
+                // This pretty horrible, but `Debug` is the only way to inspect
+                // QueryDescriptor at the moment.
+                salsa::EventKind::WillExecute { descriptor } => Some(format!("{:?}", descriptor)),
+                _ => None,
+            })
+            .collect()
+    }
+}
+
 salsa::database_storage! {
     pub(crate) struct RootDatabaseStorage for RootDatabase {
         impl crate::input::FilesDatabase {
diff --git a/crates/ra_analysis/src/descriptors/module/nameres.rs b/crates/ra_analysis/src/descriptors/module/nameres.rs
index 4c555421d..648ec5e43 100644
--- a/crates/ra_analysis/src/descriptors/module/nameres.rs
+++ b/crates/ra_analysis/src/descriptors/module/nameres.rs
@@ -358,7 +358,8 @@ where
 #[cfg(test)]
 mod tests {
     use crate::{
-        mock_analysis::analysis_and_position,
+        AnalysisChange,
+        mock_analysis::{MockAnalysis, analysis_and_position},
         descriptors::{DescriptorDatabase, module::ModuleDescriptor},
         input::FilesDatabase,
 };
@@ -396,4 +397,65 @@ mod tests {
         let resolution = &item_map.per_module[&module_id].items[&name];
         assert!(resolution.def_id.is_some());
     }
+
+    #[test]
+    fn typing_inside_a_function_should_not_invalidate_item_map() {
+        let mock_analysis = MockAnalysis::with_files(
+            "
+            //- /lib.rs
+            mod foo;
+
+            use crate::foo::bar::Baz;
+
+            fn foo() -> i32 {
+                1 + 1
+            }
+            //- /foo/mod.rs
+            pub mod bar;
+
+            //- /foo/bar.rs
+            pub struct Baz;
+        ",
+        );
+
+        let file_id = mock_analysis.id_of("/lib.rs");
+        let mut host = mock_analysis.analysis_host();
+
+        let source_root = host.analysis().imp.db.file_source_root(file_id);
+
+        {
+            let db = host.analysis().imp.db;
+            let events = db.log_executed(|| {
+                db._item_map(source_root).unwrap();
+            });
+            assert!(format!("{:?}", events).contains("_item_map"))
+        }
+
+        let mut change = AnalysisChange::new();
+
+        change.change_file(
+            file_id,
+            "
+            mod foo;
+
+            use crate::foo::bar::Baz;
+
+            fn foo() -> i32 { 92 }
+        "
+            .to_string(),
+        );
+
+        host.apply_change(change);
+
+        {
+            let db = host.analysis().imp.db;
+            let events = db.log_executed(|| {
+                db._item_map(source_root).unwrap();
+            });
+            // assert!(
+            //     !format!("{:?}", events).contains("_item_map"),
+            //     "{:#?}", events
+            // )
+        }
+    }
 }