Move lang_items to hir_def

10 files changed, 179 insertions, 202 deletions

diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index c3f698ea0..cae305f98 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -3,27 +3,25 @@
 use std::sync::Arc;
 
 use ra_db::salsa;
-use ra_syntax::SmolStr;
 
 use crate::{
     debug::HirDebugDatabase,
     ids,
-    lang_item::{LangItemTarget, LangItems},
     ty::{
         method_resolution::CrateImplBlocks,
         traits::{AssocTyValue, Impl},
         CallableDef, FnSig, GenericPredicate, InferenceResult, Namespace, Substs, Ty, TypableDef,
         TypeCtor,
     },
-    Crate, DefWithBody, GenericDef, ImplBlock, Module, StructField, Trait,
+    Crate, DefWithBody, GenericDef, ImplBlock, StructField, Trait,
 };
 
 pub use hir_def::db::{
-    BodyQuery, BodyWithSourceMapQuery, ConstDataQuery, CrateDefMapQuery, DefDatabase2,
-    DefDatabase2Storage, EnumDataQuery, ExprScopesQuery, FunctionDataQuery, GenericParamsQuery,
-    ImplDataQuery, InternDatabase, InternDatabaseStorage, RawItemsQuery,
-    RawItemsWithSourceMapQuery, StaticDataQuery, StructDataQuery, TraitDataQuery,
-    TypeAliasDataQuery,
+    BodyQuery, BodyWithSourceMapQuery, ConstDataQuery, CrateDefMapQuery, CrateLangItemsQuery,
+    DefDatabase2, DefDatabase2Storage, EnumDataQuery, ExprScopesQuery, FunctionDataQuery,
+    GenericParamsQuery, ImplDataQuery, InternDatabase, InternDatabaseStorage, LangItemQuery,
+    ModuleLangItemsQuery, RawItemsQuery, RawItemsWithSourceMapQuery, StaticDataQuery,
+    StructDataQuery, TraitDataQuery, TypeAliasDataQuery,
 };
 pub use hir_expand::db::{
     AstDatabase, AstDatabaseStorage, AstIdMapQuery, MacroArgQuery, MacroDefQuery, MacroExpandQuery,
@@ -34,15 +32,6 @@ pub use hir_expand::db::{
 #[salsa::query_group(DefDatabaseStorage)]
 #[salsa::requires(AstDatabase)]
 pub trait DefDatabase: HirDebugDatabase + DefDatabase2 {
-    #[salsa::invoke(LangItems::module_lang_items_query)]
-    fn module_lang_items(&self, module: Module) -> Option<Arc<LangItems>>;
-
-    #[salsa::invoke(LangItems::crate_lang_items_query)]
-    fn crate_lang_items(&self, krate: Crate) -> Arc<LangItems>;
-
-    #[salsa::invoke(LangItems::lang_item_query)]
-    fn lang_item(&self, start_crate: Crate, item: SmolStr) -> Option<LangItemTarget>;
-
     #[salsa::invoke(crate::code_model::docs::documentation_query)]
     fn documentation(&self, def: crate::DocDef) -> Option<crate::Documentation>;
 }
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
deleted file mode 100644
index 55f0c3a13..000000000
--- a/crates/ra_hir/src/lang_item.rs
+++ /dev/null
@@ -1,154 +0,0 @@
-//! FIXME: write short doc here
-
-use std::sync::Arc;
-
-use hir_def::{AdtId, AttrDefId, ModuleDefId};
-use ra_syntax::SmolStr;
-use rustc_hash::FxHashMap;
-
-use crate::{
-    db::{AstDatabase, DefDatabase, HirDatabase},
-    Crate, Enum, Function, ImplBlock, Module, Static, Struct, Trait,
-};
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub enum LangItemTarget {
-    Enum(Enum),
-    Function(Function),
-    ImplBlock(ImplBlock),
-    Static(Static),
-    Struct(Struct),
-    Trait(Trait),
-}
-
-impl LangItemTarget {
-    pub(crate) fn krate(&self, db: &impl HirDatabase) -> Option<Crate> {
-        Some(match self {
-            LangItemTarget::Enum(e) => e.module(db).krate(),
-            LangItemTarget::Function(f) => f.module(db).krate(),
-            LangItemTarget::ImplBlock(i) => i.krate(db),
-            LangItemTarget::Static(s) => s.module(db).krate(),
-            LangItemTarget::Struct(s) => s.module(db).krate(),
-            LangItemTarget::Trait(t) => t.module(db).krate(),
-        })
-    }
-}
-
-#[derive(Default, Debug, Clone, PartialEq, Eq)]
-pub struct LangItems {
-    items: FxHashMap<SmolStr, LangItemTarget>,
-}
-
-impl LangItems {
-    pub fn target<'a>(&'a self, item: &str) -> Option<&'a LangItemTarget> {
-        self.items.get(item)
-    }
-
-    /// Salsa query. This will look for lang items in a specific crate.
-    pub(crate) fn crate_lang_items_query(
-        db: &(impl DefDatabase + AstDatabase),
-        krate: Crate,
-    ) -> Arc<LangItems> {
-        let mut lang_items = LangItems::default();
-
-        if let Some(module) = krate.root_module(db) {
-            lang_items.collect_lang_items_recursive(db, module);
-        }
-
-        Arc::new(lang_items)
-    }
-
-    pub(crate) fn module_lang_items_query(
-        db: &(impl DefDatabase + AstDatabase),
-        module: Module,
-    ) -> Option<Arc<LangItems>> {
-        let mut lang_items = LangItems::default();
-        lang_items.collect_lang_items(db, module);
-        if lang_items.items.is_empty() {
-            None
-        } else {
-            Some(Arc::new(lang_items))
-        }
-    }
-
-    /// Salsa query. Look for a lang item, starting from the specified crate and recursively
-    /// traversing its dependencies.
-    pub(crate) fn lang_item_query(
-        db: &impl DefDatabase,
-        start_crate: Crate,
-        item: SmolStr,
-    ) -> Option<LangItemTarget> {
-        let lang_items = db.crate_lang_items(start_crate);
-        let start_crate_target = lang_items.items.get(&item);
-        if let Some(target) = start_crate_target {
-            Some(*target)
-        } else {
-            for dep in start_crate.dependencies(db) {
-                let dep_crate = dep.krate;
-                let dep_target = db.lang_item(dep_crate, item.clone());
-                if dep_target.is_some() {
-                    return dep_target;
-                }
-            }
-            None
-        }
-    }
-
-    fn collect_lang_items(&mut self, db: &(impl DefDatabase + AstDatabase), module: Module) {
-        // Look for impl targets
-        let def_map = db.crate_def_map(module.id.krate);
-        let module_data = &def_map[module.id.module_id];
-        for &impl_block in module_data.impls.iter() {
-            self.collect_lang_item(db, impl_block, LangItemTarget::ImplBlock)
-        }
-
-        for def in module_data.scope.declarations() {
-            match def {
-                ModuleDefId::TraitId(trait_) => {
-                    self.collect_lang_item(db, trait_, LangItemTarget::Trait)
-                }
-                ModuleDefId::AdtId(AdtId::EnumId(e)) => {
-                    self.collect_lang_item(db, e, LangItemTarget::Enum)
-                }
-                ModuleDefId::AdtId(AdtId::StructId(s)) => {
-                    self.collect_lang_item(db, s, LangItemTarget::Struct)
-                }
-                ModuleDefId::FunctionId(f) => {
-                    self.collect_lang_item(db, f, LangItemTarget::Function)
-                }
-                ModuleDefId::StaticId(s) => self.collect_lang_item(db, s, LangItemTarget::Static),
-                _ => {}
-            }
-        }
-    }
-
-    fn collect_lang_items_recursive(
-        &mut self,
-        db: &(impl DefDatabase + AstDatabase),
-        module: Module,
-    ) {
-        if let Some(module_lang_items) = db.module_lang_items(module) {
-            self.items.extend(module_lang_items.items.iter().map(|(k, v)| (k.clone(), *v)))
-        }
-
-        // Look for lang items in the children
-        for child in module.children(db) {
-            self.collect_lang_items_recursive(db, child);
-        }
-    }
-
-    fn collect_lang_item<T, D>(
-        &mut self,
-        db: &(impl DefDatabase + AstDatabase),
-        item: T,
-        constructor: fn(D) -> LangItemTarget,
-    ) where
-        T: Into<AttrDefId> + Copy,
-        D: From<T>,
-    {
-        let attrs = db.attrs(item.into());
-        if let Some(lang_item_name) = attrs.find_string_value("lang") {
-            self.items.entry(lang_item_name).or_insert_with(|| constructor(D::from(item)));
-        }
-    }
-}
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 152590cd1..22da05a97 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -35,7 +35,6 @@ mod ids;
 mod ty;
 mod impl_block;
 mod expr;
-mod lang_item;
 pub mod diagnostics;
 mod util;
 
diff --git a/crates/ra_hir/src/ty/autoderef.rs b/crates/ra_hir/src/ty/autoderef.rs
index b60e4bb31..41c99d227 100644
--- a/crates/ra_hir/src/ty/autoderef.rs
+++ b/crates/ra_hir/src/ty/autoderef.rs
@@ -5,12 +5,13 @@
 
 use std::iter::successors;
 
-use hir_def::resolver::Resolver;
+use hir_def::{lang_item::LangItemTarget, resolver::Resolver};
 use hir_expand::name;
 use log::{info, warn};
 
+use crate::{db::HirDatabase, Trait};
+
 use super::{traits::Solution, Canonical, Substs, Ty, TypeWalk};
-use crate::db::HirDatabase;
 
 const AUTODEREF_RECURSION_LIMIT: usize = 10;
 
@@ -41,7 +42,7 @@ fn deref_by_trait(
 ) -> Option<Canonical<Ty>> {
     let krate = resolver.krate()?;
     let deref_trait = match db.lang_item(krate.into(), "deref".into())? {
-        crate::lang_item::LangItemTarget::Trait(t) => t,
+        LangItemTarget::TraitId(t) => Trait::from(t),
         _ => return None,
     };
     let target = deref_trait.associated_type_by_name(db, &name::TARGET_TYPE)?;
diff --git a/crates/ra_hir/src/ty/infer/coerce.rs b/crates/ra_hir/src/ty/infer/coerce.rs
index 0772b9df5..4ea038d99 100644
--- a/crates/ra_hir/src/ty/infer/coerce.rs
+++ b/crates/ra_hir/src/ty/infer/coerce.rs
@@ -4,13 +4,12 @@
 //!
 //! See: https://doc.rust-lang.org/nomicon/coercions.html
 
-use hir_def::resolver::Resolver;
+use hir_def::{lang_item::LangItemTarget, resolver::Resolver};
 use rustc_hash::FxHashMap;
 use test_utils::tested_by;
 
 use crate::{
     db::HirDatabase,
-    lang_item::LangItemTarget,
     ty::{autoderef, Substs, Ty, TypeCtor, TypeWalk},
     Adt, Mutability,
 };
@@ -50,7 +49,9 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
     ) -> FxHashMap<(TypeCtor, TypeCtor), usize> {
         let krate = resolver.krate().unwrap();
         let impls = match db.lang_item(krate.into(), "coerce_unsized".into()) {
-            Some(LangItemTarget::Trait(trait_)) => db.impls_for_trait(krate.into(), trait_),
+            Some(LangItemTarget::TraitId(trait_)) => {
+                db.impls_for_trait(krate.into(), trait_.into())
+            }
             _ => return FxHashMap::default(),
         };
 
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index f61c27218..caa5f5f74 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -5,7 +5,7 @@
 use std::sync::Arc;
 
 use arrayvec::ArrayVec;
-use hir_def::resolver::Resolver;
+use hir_def::{lang_item::LangItemTarget, resolver::Resolver, AstItemDef};
 use rustc_hash::FxHashMap;
 
 use crate::{
@@ -91,34 +91,43 @@ fn def_crates(db: &impl HirDatabase, cur_crate: Crate, ty: &Ty) -> Option<ArrayV
     // Types like slice can have inherent impls in several crates, (core and alloc).
     // The corresponding impls are marked with lang items, so we can use them to find the required crates.
     macro_rules! lang_item_crate {
-        ($db:expr, $cur_crate:expr, $($name:expr),+ $(,)?) => {{
-            let mut v = ArrayVec::<[Crate; 2]>::new();
+        ($($name:expr),+ $(,)?) => {{
+            let mut v = ArrayVec::<[LangItemTarget; 2]>::new();
             $(
-                v.extend($db.lang_item($cur_crate, $name.into()).and_then(|item| item.krate($db)));
+                v.extend(db.lang_item(cur_crate.crate_id, $name.into()));
             )+
-            Some(v)
+            v
         }};
     }
 
-    match ty {
+    let lang_item_targets = match ty {
         Ty::Apply(a_ty) => match a_ty.ctor {
-            TypeCtor::Adt(def_id) => Some(std::iter::once(def_id.krate(db)?).collect()),
-            TypeCtor::Bool => lang_item_crate!(db, cur_crate, "bool"),
-            TypeCtor::Char => lang_item_crate!(db, cur_crate, "char"),
+            TypeCtor::Adt(def_id) => return Some(std::iter::once(def_id.krate(db)?).collect()),
+            TypeCtor::Bool => lang_item_crate!("bool"),
+            TypeCtor::Char => lang_item_crate!("char"),
             TypeCtor::Float(Uncertain::Known(f)) => match f.bitness {
                 // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime)
-                FloatBitness::X32 => lang_item_crate!(db, cur_crate, "f32", "f32_runtime"),
-                FloatBitness::X64 => lang_item_crate!(db, cur_crate, "f64", "f64_runtime"),
+                FloatBitness::X32 => lang_item_crate!("f32", "f32_runtime"),
+                FloatBitness::X64 => lang_item_crate!("f64", "f64_runtime"),
             },
-            TypeCtor::Int(Uncertain::Known(i)) => lang_item_crate!(db, cur_crate, i.ty_to_string()),
-            TypeCtor::Str => lang_item_crate!(db, cur_crate, "str_alloc", "str"),
-            TypeCtor::Slice => lang_item_crate!(db, cur_crate, "slice_alloc", "slice"),
-            TypeCtor::RawPtr(Mutability::Shared) => lang_item_crate!(db, cur_crate, "const_ptr"),
-            TypeCtor::RawPtr(Mutability::Mut) => lang_item_crate!(db, cur_crate, "mut_ptr"),
-            _ => None,
+            TypeCtor::Int(Uncertain::Known(i)) => lang_item_crate!(i.ty_to_string()),
+            TypeCtor::Str => lang_item_crate!("str_alloc", "str"),
+            TypeCtor::Slice => lang_item_crate!("slice_alloc", "slice"),
+            TypeCtor::RawPtr(Mutability::Shared) => lang_item_crate!("const_ptr"),
+            TypeCtor::RawPtr(Mutability::Mut) => lang_item_crate!("mut_ptr"),
+            _ => return None,
         },
-        _ => None,
-    }
+        _ => return None,
+    };
+    let res = lang_item_targets
+        .into_iter()
+        .filter_map(|it| match it {
+            LangItemTarget::ImplBlockId(it) => Some(it),
+            _ => None,
+        })
+        .map(|it| it.module(db).krate.into())
+        .collect();
+    Some(res)
 }
 
 /// Look up the method with the given name, returning the actual autoderefed
diff --git a/crates/ra_hir/src/ty/traits/chalk.rs b/crates/ra_hir/src/ty/traits/chalk.rs
index 88785f305..53818a5e5 100644
--- a/crates/ra_hir/src/ty/traits/chalk.rs
+++ b/crates/ra_hir/src/ty/traits/chalk.rs
@@ -9,6 +9,7 @@ use chalk_ir::{
 };
 use chalk_rust_ir::{AssociatedTyDatum, AssociatedTyValue, ImplDatum, StructDatum, TraitDatum};
 
+use hir_def::lang_item::LangItemTarget;
 use hir_expand::name;
 
 use ra_db::salsa::{InternId, InternKey};
@@ -832,9 +833,9 @@ fn closure_fn_trait_output_assoc_ty_value(
 }
 
 fn get_fn_trait(db: &impl HirDatabase, krate: Crate, fn_trait: super::FnTrait) -> Option<Trait> {
-    let target = db.lang_item(krate, fn_trait.lang_item_name().into())?;
+    let target = db.lang_item(krate.crate_id, fn_trait.lang_item_name().into())?;
     match target {
-        crate::lang_item::LangItemTarget::Trait(t) => Some(t),
+        LangItemTarget::TraitId(t) => Some(t.into()),
         _ => None,
     }
 }
diff --git a/crates/ra_hir_def/src/db.rs b/crates/ra_hir_def/src/db.rs
index e91e741bb..e87bd525a 100644
--- a/crates/ra_hir_def/src/db.rs
+++ b/crates/ra_hir_def/src/db.rs
@@ -3,7 +3,7 @@ use std::sync::Arc;
 
 use hir_expand::{db::AstDatabase, HirFileId};
 use ra_db::{salsa, CrateId, SourceDatabase};
-use ra_syntax::ast;
+use ra_syntax::{ast, SmolStr};
 
 use crate::{
     adt::{EnumData, StructData},
@@ -11,12 +11,13 @@ use crate::{
     body::{scope::ExprScopes, Body, BodySourceMap},
     data::{ConstData, FunctionData, ImplData, TraitData, TypeAliasData},
     generics::GenericParams,
+    lang_item::{LangItemTarget, LangItems},
     nameres::{
         raw::{ImportSourceMap, RawItems},
         CrateDefMap,
     },
-    AttrDefId, ConstId, DefWithBodyId, EnumId, FunctionId, GenericDefId, ImplId, ItemLoc, StaticId,
-    StructOrUnionId, TraitId, TypeAliasId,
+    AttrDefId, ConstId, DefWithBodyId, EnumId, FunctionId, GenericDefId, ImplId, ItemLoc, ModuleId,
+    StaticId, StructOrUnionId, TraitId, TypeAliasId,
 };
 
 #[salsa::query_group(InternDatabaseStorage)]
@@ -91,4 +92,13 @@ pub trait DefDatabase2: InternDatabase + AstDatabase {
 
     #[salsa::invoke(Attrs::attrs_query)]
     fn attrs(&self, def: AttrDefId) -> Attrs;
+
+    #[salsa::invoke(LangItems::module_lang_items_query)]
+    fn module_lang_items(&self, module: ModuleId) -> Option<Arc<LangItems>>;
+
+    #[salsa::invoke(LangItems::crate_lang_items_query)]
+    fn crate_lang_items(&self, krate: CrateId) -> Arc<LangItems>;
+
+    #[salsa::invoke(LangItems::lang_item_query)]
+    fn lang_item(&self, start_crate: CrateId, item: SmolStr) -> Option<LangItemTarget>;
 }
diff --git a/crates/ra_hir_def/src/lang_item.rs b/crates/ra_hir_def/src/lang_item.rs
new file mode 100644
index 000000000..4c1a764ea
--- /dev/null
+++ b/crates/ra_hir_def/src/lang_item.rs
@@ -0,0 +1,120 @@
+//! Collects lang items: items marked with `#[lang = "..."]` attribute.
+//!
+//! This attribute to tell the compiler about semi built-in std library
+//! features, such as Fn family of traits.
+use std::sync::Arc;
+
+use ra_syntax::SmolStr;
+use rustc_hash::FxHashMap;
+
+use crate::{
+    db::DefDatabase2, AdtId, AttrDefId, CrateId, EnumId, FunctionId, ImplId, ModuleDefId, ModuleId,
+    StaticId, StructId, TraitId,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum LangItemTarget {
+    EnumId(EnumId),
+    FunctionId(FunctionId),
+    ImplBlockId(ImplId),
+    StaticId(StaticId),
+    StructId(StructId),
+    TraitId(TraitId),
+}
+
+#[derive(Default, Debug, Clone, PartialEq, Eq)]
+pub struct LangItems {
+    items: FxHashMap<SmolStr, LangItemTarget>,
+}
+
+impl LangItems {
+    pub fn target<'a>(&'a self, item: &str) -> Option<&'a LangItemTarget> {
+        self.items.get(item)
+    }
+
+    /// Salsa query. This will look for lang items in a specific crate.
+    pub(crate) fn crate_lang_items_query(db: &impl DefDatabase2, krate: CrateId) -> Arc<LangItems> {
+        let mut lang_items = LangItems::default();
+
+        let crate_def_map = db.crate_def_map(krate);
+
+        crate_def_map
+            .modules()
+            .filter_map(|module_id| db.module_lang_items(ModuleId { krate, module_id }))
+            .for_each(|it| lang_items.items.extend(it.items.iter().map(|(k, v)| (k.clone(), *v))));
+
+        Arc::new(lang_items)
+    }
+
+    pub(crate) fn module_lang_items_query(
+        db: &impl DefDatabase2,
+        module: ModuleId,
+    ) -> Option<Arc<LangItems>> {
+        let mut lang_items = LangItems::default();
+        lang_items.collect_lang_items(db, module);
+        if lang_items.items.is_empty() {
+            None
+        } else {
+            Some(Arc::new(lang_items))
+        }
+    }
+
+    /// Salsa query. Look for a lang item, starting from the specified crate and recursively
+    /// traversing its dependencies.
+    pub(crate) fn lang_item_query(
+        db: &impl DefDatabase2,
+        start_crate: CrateId,
+        item: SmolStr,
+    ) -> Option<LangItemTarget> {
+        let lang_items = db.crate_lang_items(start_crate);
+        let start_crate_target = lang_items.items.get(&item);
+        if let Some(target) = start_crate_target {
+            return Some(*target);
+        }
+        db.crate_graph()
+            .dependencies(start_crate)
+            .find_map(|dep| db.lang_item(dep.crate_id, item.clone()))
+    }
+
+    fn collect_lang_items(&mut self, db: &impl DefDatabase2, module: ModuleId) {
+        // Look for impl targets
+        let def_map = db.crate_def_map(module.krate);
+        let module_data = &def_map[module.module_id];
+        for &impl_block in module_data.impls.iter() {
+            self.collect_lang_item(db, impl_block, LangItemTarget::ImplBlockId)
+        }
+
+        for def in module_data.scope.declarations() {
+            match def {
+                ModuleDefId::TraitId(trait_) => {
+                    self.collect_lang_item(db, trait_, LangItemTarget::TraitId)
+                }
+                ModuleDefId::AdtId(AdtId::EnumId(e)) => {
+                    self.collect_lang_item(db, e, LangItemTarget::EnumId)
+                }
+                ModuleDefId::AdtId(AdtId::StructId(s)) => {
+                    self.collect_lang_item(db, s, LangItemTarget::StructId)
+                }
+                ModuleDefId::FunctionId(f) => {
+                    self.collect_lang_item(db, f, LangItemTarget::FunctionId)
+                }
+                ModuleDefId::StaticId(s) => self.collect_lang_item(db, s, LangItemTarget::StaticId),
+                _ => {}
+            }
+        }
+    }
+
+    fn collect_lang_item<T>(
+        &mut self,
+        db: &impl DefDatabase2,
+        item: T,
+        constructor: fn(T) -> LangItemTarget,
+    ) where
+        T: Into<AttrDefId> + Copy,
+    {
+        let attrs = db.attrs(item.into());
+        if let Some(lang_item_name) = attrs.find_string_value("lang") {
+            self.items.entry(lang_item_name).or_insert_with(|| constructor(item));
+        }
+    }
+}
diff --git a/crates/ra_hir_def/src/lib.rs b/crates/ra_hir_def/src/lib.rs
index 20d4deadb..899510be4 100644
--- a/crates/ra_hir_def/src/lib.rs
+++ b/crates/ra_hir_def/src/lib.rs
@@ -19,6 +19,7 @@ pub mod body;
 pub mod generics;
 pub mod resolver;
 pub mod data;
+pub mod lang_item;
 
 mod trace;