3 files changed, 90 insertions, 3 deletions

diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 4296c6304..d9d6c91a8 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -477,16 +477,21 @@ impl DefCollector<'_> {
     /// going out of sync with what the build system sees (since we resolve using VFS state, but
     /// Cargo builds only on-disk files). We could and probably should add diagnostics for that.
     fn export_proc_macro(&mut self, def: ProcMacroDef, ast_id: AstId<ast::Fn>) {
+        let kind = def.kind.to_basedb_kind();
         self.exports_proc_macros = true;
         let macro_def = match self.proc_macros.iter().find(|(n, _)| n == &def.name) {
             Some((_, expander)) => MacroDefId {
                 krate: self.def_map.krate,
-                kind: MacroDefKind::ProcMacro(*expander, ast_id),
+                kind: MacroDefKind::ProcMacro(*expander, kind, ast_id),
                 local_inner: false,
             },
             None => MacroDefId {
                 krate: self.def_map.krate,
-                kind: MacroDefKind::ProcMacro(ProcMacroExpander::dummy(self.def_map.krate), ast_id),
+                kind: MacroDefKind::ProcMacro(
+                    ProcMacroExpander::dummy(self.def_map.krate),
+                    kind,
+                    ast_id,
+                ),
                 local_inner: false,
             },
         };
diff --git a/crates/hir_def/src/nameres/proc_macro.rs b/crates/hir_def/src/nameres/proc_macro.rs
index 156598f19..3f095d623 100644
--- a/crates/hir_def/src/nameres/proc_macro.rs
+++ b/crates/hir_def/src/nameres/proc_macro.rs
@@ -18,6 +18,16 @@ pub(super) enum ProcMacroKind {
     Attr,
 }
 
+impl ProcMacroKind {
+    pub(super) fn to_basedb_kind(&self) -> base_db::ProcMacroKind {
+        match self {
+            ProcMacroKind::CustomDerive { .. } => base_db::ProcMacroKind::CustomDerive,
+            ProcMacroKind::FnLike => base_db::ProcMacroKind::FuncLike,
+            ProcMacroKind::Attr => base_db::ProcMacroKind::Attr,
+        }
+    }
+}
+
 impl Attrs {
     #[rustfmt::skip]
     pub(super) fn parse_proc_macro_decl(&self, func_name: &Name) -> Option<ProcMacroDef> {
diff --git a/crates/hir_def/src/nameres/tests/incremental.rs b/crates/hir_def/src/nameres/tests/incremental.rs
index d884a6eb4..7bf152e26 100644
--- a/crates/hir_def/src/nameres/tests/incremental.rs
+++ b/crates/hir_def/src/nameres/tests/incremental.rs
@@ -1,6 +1,8 @@
 use std::sync::Arc;
 
-use base_db::SourceDatabaseExt;
+use base_db::{salsa::SweepStrategy, SourceDatabaseExt};
+
+use crate::{AdtId, ModuleDefId};
 
 use super::*;
 
@@ -163,3 +165,73 @@ m!(Z);
         assert_eq!(n_reparsed_macros, 0);
     }
 }
+
+#[test]
+fn item_tree_prevents_reparsing() {
+    // The `ItemTree` is used by both name resolution and the various queries in `adt.rs` and
+    // `data.rs`. After computing the `ItemTree` and deleting the parse tree, we should be able to
+    // run those other queries without triggering a reparse.
+
+    let (db, pos) = TestDB::with_position(
+        r#"
+pub struct S;
+pub union U {}
+pub enum E {
+    Variant,
+}
+pub fn f(_: S) { $0 }
+pub trait Tr {}
+impl Tr for () {}
+pub const C: u8 = 0;
+pub static ST: u8 = 0;
+pub type Ty = ();
+"#,
+    );
+    let krate = db.test_crate();
+    {
+        let events = db.log_executed(|| {
+            db.file_item_tree(pos.file_id.into());
+        });
+        let n_calculated_item_trees = events.iter().filter(|it| it.contains("item_tree")).count();
+        assert_eq!(n_calculated_item_trees, 1);
+        let n_parsed_files = events.iter().filter(|it| it.contains("parse(")).count();
+        assert_eq!(n_parsed_files, 1);
+    }
+
+    // Delete the parse tree.
+    let sweep = SweepStrategy::default().discard_values().sweep_all_revisions();
+    base_db::ParseQuery.in_db(&db).sweep(sweep);
+
+    {
+        let events = db.log_executed(|| {
+            let crate_def_map = db.crate_def_map(krate);
+            let (_, module_data) = crate_def_map.modules.iter().last().unwrap();
+            assert_eq!(module_data.scope.resolutions().count(), 8);
+            assert_eq!(module_data.scope.impls().count(), 1);
+
+            for imp in module_data.scope.impls() {
+                db.impl_data(imp);
+            }
+
+            for (_, res) in module_data.scope.resolutions() {
+                match res.values.or(res.types).unwrap().0 {
+                    ModuleDefId::FunctionId(f) => drop(db.function_data(f)),
+                    ModuleDefId::AdtId(adt) => match adt {
+                        AdtId::StructId(it) => drop(db.struct_data(it)),
+                        AdtId::UnionId(it) => drop(db.union_data(it)),
+                        AdtId::EnumId(it) => drop(db.enum_data(it)),
+                    },
+                    ModuleDefId::ConstId(it) => drop(db.const_data(it)),
+                    ModuleDefId::StaticId(it) => drop(db.static_data(it)),
+                    ModuleDefId::TraitId(it) => drop(db.trait_data(it)),
+                    ModuleDefId::TypeAliasId(it) => drop(db.type_alias_data(it)),
+                    ModuleDefId::EnumVariantId(_)
+                    | ModuleDefId::ModuleId(_)
+                    | ModuleDefId::BuiltinType(_) => unreachable!(),
+                }
+            }
+        });
+        let n_reparsed_files = events.iter().filter(|it| it.contains("parse(")).count();
+        assert_eq!(n_reparsed_files, 0);
+    }
+}