5 files changed, 243 insertions, 78 deletions

diff --git a/crates/hir_def/src/nameres/collector.rs b/crates/hir_def/src/nameres/collector.rs
index 014ea4de4..d9d6c91a8 100644
--- a/crates/hir_def/src/nameres/collector.rs
+++ b/crates/hir_def/src/nameres/collector.rs
@@ -17,6 +17,7 @@ use hir_expand::{
 };
 use hir_expand::{InFile, MacroCallLoc};
 use itertools::Itertools;
+use la_arena::Idx;
 use rustc_hash::{FxHashMap, FxHashSet};
 use syntax::ast;
 
@@ -33,7 +34,10 @@ use crate::{
     },
     macro_call_as_call_id,
     nameres::{
-        diagnostics::DefDiagnostic, mod_resolution::ModDir, path_resolution::ReachedFixedPoint,
+        diagnostics::DefDiagnostic,
+        mod_resolution::ModDir,
+        path_resolution::ReachedFixedPoint,
+        proc_macro::{ProcMacroDef, ProcMacroKind},
         BuiltinShadowMode, DefMap, ModuleData, ModuleOrigin, ResolveMode,
     },
     path::{ImportAlias, ModPath, PathKind},
@@ -44,8 +48,6 @@ use crate::{
     UnresolvedMacro,
 };
 
-use super::proc_macro::{ProcMacroDef, ProcMacroKind};
-
 const GLOB_RECURSION_LIMIT: usize = 100;
 const EXPANSION_DEPTH_LIMIT: usize = 128;
 const FIXED_POINT_LIMIT: usize = 8192;
@@ -142,7 +144,7 @@ impl PartialResolvedImport {
 
 #[derive(Clone, Debug, Eq, PartialEq)]
 enum ImportSource {
-    Import(ItemTreeId<item_tree::Import>),
+    Import { id: ItemTreeId<item_tree::Import>, use_tree: Idx<ast::UseTree> },
     ExternCrate(ItemTreeId<item_tree::ExternCrate>),
 }
 
@@ -164,20 +166,26 @@ impl Import {
         krate: CrateId,
         tree: &ItemTree,
         id: ItemTreeId<item_tree::Import>,
-    ) -> Self {
+    ) -> Vec<Self> {
         let it = &tree[id.value];
         let attrs = &tree.attrs(db, krate, ModItem::from(id.value).into());
         let visibility = &tree[it.visibility];
-        Self {
-            path: it.path.clone(),
-            alias: it.alias.clone(),
-            visibility: visibility.clone(),
-            is_glob: it.is_glob,
-            is_prelude: attrs.by_key("prelude_import").exists(),
-            is_extern_crate: false,
-            is_macro_use: false,
-            source: ImportSource::Import(id),
-        }
+        let is_prelude = attrs.by_key("prelude_import").exists();
+
+        let mut res = Vec::new();
+        it.use_tree.expand(|idx, path, is_glob, alias| {
+            res.push(Self {
+                path: Interned::new(path), // FIXME this makes little sense
+                alias,
+                visibility: visibility.clone(),
+                is_glob,
+                is_prelude,
+                is_extern_crate: false,
+                is_macro_use: false,
+                source: ImportSource::Import { id, use_tree: idx },
+            });
+        });
+        res
     }
 
     fn from_extern_crate(
@@ -285,7 +293,7 @@ impl DefCollector<'_> {
                 let registered_name = if *attr_name == hir_expand::name![register_attr]
                     || *attr_name == hir_expand::name![register_tool]
                 {
-                    match &attr.input {
+                    match attr.input.as_deref() {
                         Some(AttrInput::TokenTree(subtree)) => match &*subtree.token_trees {
                             [tt::TokenTree::Leaf(tt::Leaf::Ident(name))] => name.as_name(),
                             _ => continue,
@@ -469,16 +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,
             },
         };
@@ -1129,11 +1142,8 @@ impl DefCollector<'_> {
         }
 
         for directive in &self.unresolved_imports {
-            if let ImportSource::Import(import) = &directive.import.source {
-                let item_tree = import.item_tree(self.db);
-                let import_data = &item_tree[import.value];
-
-                match (import_data.path.segments().first(), &import_data.path.kind) {
+            if let ImportSource::Import { id: import, use_tree } = &directive.import.source {
+                match (directive.import.path.segments().first(), &directive.import.path.kind) {
                     (Some(krate), PathKind::Plain) | (Some(krate), PathKind::Abs) => {
                         if diagnosed_extern_crates.contains(krate) {
                             continue;
@@ -1144,8 +1154,8 @@ impl DefCollector<'_> {
 
                 self.def_map.diagnostics.push(DefDiagnostic::unresolved_import(
                     directive.module_id,
-                    InFile::new(import.file_id(), import_data.ast_id),
-                    import_data.index,
+                    *import,
+                    *use_tree,
                 ));
             }
         }
@@ -1221,16 +1231,20 @@ impl ModCollector<'_, '_> {
             match item {
                 ModItem::Mod(m) => self.collect_module(&self.item_tree[m], &attrs),
                 ModItem::Import(import_id) => {
-                    self.def_collector.unresolved_imports.push(ImportDirective {
-                        module_id: self.module_id,
-                        import: Import::from_use(
-                            self.def_collector.db,
-                            krate,
-                            &self.item_tree,
-                            ItemTreeId::new(self.file_id, import_id),
-                        ),
-                        status: PartialResolvedImport::Unresolved,
-                    })
+                    let module_id = self.module_id;
+                    let imports = Import::from_use(
+                        self.def_collector.db,
+                        krate,
+                        &self.item_tree,
+                        ItemTreeId::new(self.file_id, import_id),
+                    );
+                    self.def_collector.unresolved_imports.extend(imports.into_iter().map(
+                        |import| ImportDirective {
+                            module_id,
+                            import,
+                            status: PartialResolvedImport::Unresolved,
+                        },
+                    ));
                 }
                 ModItem::ExternCrate(import_id) => {
                     self.def_collector.unresolved_imports.push(ImportDirective {
diff --git a/crates/hir_def/src/nameres/diagnostics.rs b/crates/hir_def/src/nameres/diagnostics.rs
new file mode 100644
index 000000000..57c36c3c6
--- /dev/null
+++ b/crates/hir_def/src/nameres/diagnostics.rs
@@ -0,0 +1,96 @@
+//! Diagnostics emitted during DefMap construction.
+
+use cfg::{CfgExpr, CfgOptions};
+use hir_expand::MacroCallKind;
+use la_arena::Idx;
+use syntax::ast;
+
+use crate::{
+    item_tree::{self, ItemTreeId},
+    nameres::LocalModuleId,
+    path::ModPath,
+    AstId,
+};
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum DefDiagnosticKind {
+    UnresolvedModule { ast: AstId<ast::Module>, candidate: String },
+
+    UnresolvedExternCrate { ast: AstId<ast::ExternCrate> },
+
+    UnresolvedImport { id: ItemTreeId<item_tree::Import>, index: Idx<ast::UseTree> },
+
+    UnconfiguredCode { ast: AstId<ast::Item>, cfg: CfgExpr, opts: CfgOptions },
+
+    UnresolvedProcMacro { ast: MacroCallKind },
+
+    UnresolvedMacroCall { ast: AstId<ast::MacroCall>, path: ModPath },
+
+    MacroError { ast: MacroCallKind, message: String },
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct DefDiagnostic {
+    pub in_module: LocalModuleId,
+    pub kind: DefDiagnosticKind,
+}
+
+impl DefDiagnostic {
+    pub(super) fn unresolved_module(
+        container: LocalModuleId,
+        declaration: AstId<ast::Module>,
+        candidate: String,
+    ) -> Self {
+        Self {
+            in_module: container,
+            kind: DefDiagnosticKind::UnresolvedModule { ast: declaration, candidate },
+        }
+    }
+
+    pub(super) fn unresolved_extern_crate(
+        container: LocalModuleId,
+        declaration: AstId<ast::ExternCrate>,
+    ) -> Self {
+        Self {
+            in_module: container,
+            kind: DefDiagnosticKind::UnresolvedExternCrate { ast: declaration },
+        }
+    }
+
+    pub(super) fn unresolved_import(
+        container: LocalModuleId,
+        id: ItemTreeId<item_tree::Import>,
+        index: Idx<ast::UseTree>,
+    ) -> Self {
+        Self { in_module: container, kind: DefDiagnosticKind::UnresolvedImport { id, index } }
+    }
+
+    pub(super) fn unconfigured_code(
+        container: LocalModuleId,
+        ast: AstId<ast::Item>,
+        cfg: CfgExpr,
+        opts: CfgOptions,
+    ) -> Self {
+        Self { in_module: container, kind: DefDiagnosticKind::UnconfiguredCode { ast, cfg, opts } }
+    }
+
+    pub(super) fn unresolved_proc_macro(container: LocalModuleId, ast: MacroCallKind) -> Self {
+        Self { in_module: container, kind: DefDiagnosticKind::UnresolvedProcMacro { ast } }
+    }
+
+    pub(super) fn macro_error(
+        container: LocalModuleId,
+        ast: MacroCallKind,
+        message: String,
+    ) -> Self {
+        Self { in_module: container, kind: DefDiagnosticKind::MacroError { ast, message } }
+    }
+
+    pub(super) fn unresolved_macro_call(
+        container: LocalModuleId,
+        ast: AstId<ast::MacroCall>,
+        path: ModPath,
+    ) -> Self {
+        Self { in_module: container, kind: DefDiagnosticKind::UnresolvedMacroCall { ast, path } }
+    }
+}
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/diagnostics.rs b/crates/hir_def/src/nameres/tests/diagnostics.rs
index 75147d973..ec6670952 100644
--- a/crates/hir_def/src/nameres/tests/diagnostics.rs
+++ b/crates/hir_def/src/nameres/tests/diagnostics.rs
@@ -18,7 +18,7 @@ fn unresolved_import() {
         r"
         use does_exist;
         use does_not_exist;
-          //^^^^^^^^^^^^^^ unresolved import
+      //^^^^^^^^^^^^^^^^^^^ UnresolvedImport
 
         mod does_exist {}
         ",
@@ -26,40 +26,13 @@ fn unresolved_import() {
 }
 
 #[test]
-fn unresolved_import_in_use_tree() {
-    // Only the relevant part of a nested `use` item should be highlighted.
-    check_diagnostics(
-        r"
-        use does_exist::{Exists, DoesntExist};
-                               //^^^^^^^^^^^ unresolved import
-
-        use {does_not_exist::*, does_exist};
-           //^^^^^^^^^^^^^^^^^ unresolved import
-
-        use does_not_exist::{
-            a,
-          //^ unresolved import
-            b,
-          //^ unresolved import
-            c,
-          //^ unresolved import
-        };
-
-        mod does_exist {
-            pub struct Exists;
-        }
-        ",
-    );
-}
-
-#[test]
 fn unresolved_extern_crate() {
     check_diagnostics(
         r"
         //- /main.rs crate:main deps:core
         extern crate core;
           extern crate doesnotexist;
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^ unresolved extern crate
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^ UnresolvedExternCrate
         //- /lib.rs crate:core
         ",
     );
@@ -72,7 +45,7 @@ fn extern_crate_self_as() {
         r"
         //- /lib.rs
           extern crate doesnotexist;
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^ unresolved extern crate
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^ UnresolvedExternCrate
         // Should not error.
         extern crate self as foo;
         struct Foo;
@@ -88,18 +61,18 @@ fn dedup_unresolved_import_from_unresolved_crate() {
         //- /main.rs crate:main
         mod a {
             extern crate doesnotexist;
-          //^^^^^^^^^^^^^^^^^^^^^^^^^^ unresolved extern crate
+          //^^^^^^^^^^^^^^^^^^^^^^^^^^ UnresolvedExternCrate
 
             // Should not error, since we already errored for the missing crate.
             use doesnotexist::{self, bla, *};
 
             use crate::doesnotexist;
-              //^^^^^^^^^^^^^^^^^^^ unresolved import
+          //^^^^^^^^^^^^^^^^^^^^^^^^ UnresolvedImport
         }
 
         mod m {
             use super::doesnotexist;
-              //^^^^^^^^^^^^^^^^^^^ unresolved import
+          //^^^^^^^^^^^^^^^^^^^^^^^^ UnresolvedImport
         }
         ",
     );
@@ -112,7 +85,7 @@ fn unresolved_module() {
         //- /lib.rs
         mod foo;
           mod bar;
-        //^^^^^^^^ unresolved module
+        //^^^^^^^^ UnresolvedModule
         mod baz {}
         //- /foo.rs
         ",
@@ -127,16 +100,16 @@ fn inactive_item() {
         r#"
         //- /lib.rs
           #[cfg(no)] pub fn f() {}
-        //^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
 
           #[cfg(no)] #[cfg(no2)] mod m;
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no and no2 are disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
 
           #[cfg(all(not(a), b))] enum E {}
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: b is disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
 
           #[cfg(feature = "std")] use std;
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: feature = "std" is disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
         "#,
     );
 }
@@ -149,14 +122,14 @@ fn inactive_via_cfg_attr() {
         r#"
         //- /lib.rs
           #[cfg_attr(not(never), cfg(no))] fn f() {}
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
 
           #[cfg_attr(not(never), cfg(not(no)))] fn f() {}
 
           #[cfg_attr(never, cfg(no))] fn g() {}
 
           #[cfg_attr(not(never), inline, cfg(no))] fn h() {}
-        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+        //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ UnconfiguredCode
         "#,
     );
 }
@@ -170,7 +143,7 @@ fn unresolved_legacy_scope_macro() {
 
           m!();
           m2!();
-        //^^^^^^ unresolved macro `self::m2!`
+        //^^^^^^ UnresolvedMacroCall
         "#,
     );
 }
@@ -187,7 +160,7 @@ fn unresolved_module_scope_macro() {
 
           self::m!();
           self::m2!();
-        //^^^^^^^^^^^^ unresolved macro `self::m2!`
+        //^^^^^^^^^^^^ UnresolvedMacroCall
         "#,
     );
 }
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);
+    }
+}