Remove unused trace module

crates/hir-def/src/data/adt.rs

@@ -5,14 +5,10 @@ use bitflags::bitflags;
 use cfg::CfgOptions;
 use either::Either;
 
-use hir_expand::{
-    name::{AsName, Name},
-    InFile,
-};
+use hir_expand::name::Name;
 use intern::{sym, Interned};
 use la_arena::Arena;
 use rustc_abi::{Align, Integer, IntegerType, ReprFlags, ReprOptions};
-use syntax::ast::{self, HasName, HasVisibility};
 use triomphe::Arc;
 
 use crate::{
@@ -22,9 +18,7 @@ use crate::{
         AttrOwner, Field, FieldParent, FieldsShape, ItemTree, ModItem, RawVisibilityId, TreeId,
     },
     lang_item::LangItem,
-    lower::LowerCtx,
     nameres::diagnostics::{DefDiagnostic, DefDiagnostics},
-    trace::Trace,
     tt::{Delimiter, DelimiterKind, Leaf, Subtree, TokenTree},
     type_ref::TypeRef,
     visibility::RawVisibility,
@@ -409,64 +403,6 @@ pub enum StructKind {
     Unit,
 }
 
-// FIXME This is only used for mapping back source now?
-pub(crate) fn lower_struct(
-    db: &dyn DefDatabase,
-    trace: &mut Trace<FieldData, Either<ast::TupleField, ast::RecordField>>,
-    ast: &InFile<ast::StructKind>,
-    krate: CrateId,
-    item_tree: &ItemTree,
-    parent: FieldParent,
-) -> StructKind {
-    let ctx = LowerCtx::new(db, ast.file_id);
-
-    match &ast.value {
-        ast::StructKind::Tuple(fl) => {
-            let cfg_options = &db.crate_graph()[krate].cfg_options;
-            for (i, fd) in fl.fields().enumerate() {
-                let attrs = item_tree.attrs(db, krate, AttrOwner::make_field_indexed(parent, i));
-                if !attrs.is_cfg_enabled(cfg_options) {
-                    continue;
-                }
-
-                trace.alloc(
-                    || Either::Left(fd.clone()),
-                    || FieldData {
-                        name: Name::new_tuple_field(i),
-                        type_ref: Interned::new(TypeRef::from_ast_opt(&ctx, fd.ty())),
-                        visibility: RawVisibility::from_ast(db, fd.visibility(), &mut |range| {
-                            ctx.span_map().span_for_range(range).ctx
-                        }),
-                    },
-                );
-            }
-            StructKind::Tuple
-        }
-        ast::StructKind::Record(fl) => {
-            let cfg_options = &db.crate_graph()[krate].cfg_options;
-            for (i, fd) in fl.fields().enumerate() {
-                let attrs = item_tree.attrs(db, krate, AttrOwner::make_field_indexed(parent, i));
-                if !attrs.is_cfg_enabled(cfg_options) {
-                    continue;
-                }
-
-                trace.alloc(
-                    || Either::Right(fd.clone()),
-                    || FieldData {
-                        name: fd.name().map(|n| n.as_name()).unwrap_or_else(Name::missing),
-                        type_ref: Interned::new(TypeRef::from_ast_opt(&ctx, fd.ty())),
-                        visibility: RawVisibility::from_ast(db, fd.visibility(), &mut |range| {
-                            ctx.span_map().span_for_range(range).ctx
-                        }),
-                    },
-                );
-            }
-            StructKind::Record
-        }
-        _ => StructKind::Unit,
-    }
-}
-
 fn lower_fields(
     db: &dyn DefDatabase,
     krate: CrateId,

crates/hir-def/src/lib.rs

@@ -46,7 +46,6 @@ pub mod body;
 pub mod resolver;
 
 pub mod nameres;
-mod trace;
 
 pub mod child_by_source;
 pub mod src;

crates/hir-def/src/src.rs

@@ -6,10 +6,8 @@ use la_arena::ArenaMap;
 use syntax::{ast, AstNode, AstPtr};
 
 use crate::{
-    data::adt::lower_struct,
     db::DefDatabase,
-    item_tree::{FieldParent, ItemTreeNode},
-    trace::Trace,
+    item_tree::{AttrOwner, FieldParent, ItemTreeNode},
     GenericDefId, ItemTreeLoc, LocalFieldId, LocalLifetimeParamId, LocalTypeOrConstParamId, Lookup,
     UseId, VariantId,
 };
@@ -156,8 +154,49 @@ impl HasChildSource<LocalFieldId> for VariantId {
                 )
             }
         };
-        let mut trace = Trace::new_for_map();
-        lower_struct(db, &mut trace, &src, container.krate, &item_tree, parent);
-        src.with_value(trace.into_map())
+
+        let mut map = ArenaMap::new();
+        match &src.value {
+            ast::StructKind::Tuple(fl) => {
+                let cfg_options = &db.crate_graph()[container.krate].cfg_options;
+                let mut idx = 0;
+                for (i, fd) in fl.fields().enumerate() {
+                    let attrs = item_tree.attrs(
+                        db,
+                        container.krate,
+                        AttrOwner::make_field_indexed(parent, i),
+                    );
+                    if !attrs.is_cfg_enabled(cfg_options) {
+                        continue;
+                    }
+                    map.insert(
+                        LocalFieldId::from_raw(la_arena::RawIdx::from(idx)),
+                        Either::Left(fd.clone()),
+                    );
+                    idx += 1;
+                }
+            }
+            ast::StructKind::Record(fl) => {
+                let cfg_options = &db.crate_graph()[container.krate].cfg_options;
+                let mut idx = 0;
+                for (i, fd) in fl.fields().enumerate() {
+                    let attrs = item_tree.attrs(
+                        db,
+                        container.krate,
+                        AttrOwner::make_field_indexed(parent, i),
+                    );
+                    if !attrs.is_cfg_enabled(cfg_options) {
+                        continue;
+                    }
+                    map.insert(
+                        LocalFieldId::from_raw(la_arena::RawIdx::from(idx)),
+                        Either::Right(fd.clone()),
+                    );
+                    idx += 1;
+                }
+            }
+            _ => (),
+        }
+        InFile::new(src.file_id, map)
     }
 }

crates/hir-def/src/trace.rs

@@ -1,55 +0,0 @@
-//! Trace is a pretty niche data structure which is used when lowering a CST
-//! into HIR.
-//!
-//! Lowering process calculates two bits of information:
-//! * the lowered syntax itself
-//! * a mapping between lowered syntax and original syntax
-//!
-//! Due to the way salsa works, the mapping is usually hot lava, as it contains
-//! absolute offsets. The `Trace` structure (inspired, at least in name, by
-//! Kotlin's `BindingTrace`) allows use the same code to compute both
-//! projections.
-use la_arena::{Arena, ArenaMap, Idx, RawIdx};
-
-// FIXME: This isn't really used anymore, at least not in a way where it does anything useful.
-// Check if we should get rid of this or make proper use of it instead.
-pub(crate) struct Trace<T, V> {
-    arena: Option<Arena<T>>,
-    map: Option<ArenaMap<Idx<T>, V>>,
-    len: u32,
-}
-
-impl<T, V> Trace<T, V> {
-    #[allow(dead_code)]
-    pub(crate) fn new_for_arena() -> Trace<T, V> {
-        Trace { arena: Some(Arena::default()), map: None, len: 0 }
-    }
-
-    pub(crate) fn new_for_map() -> Trace<T, V> {
-        Trace { arena: None, map: Some(ArenaMap::default()), len: 0 }
-    }
-
-    pub(crate) fn alloc(&mut self, value: impl FnOnce() -> V, data: impl FnOnce() -> T) -> Idx<T> {
-        let id = if let Some(arena) = &mut self.arena {
-            arena.alloc(data())
-        } else {
-            let id = Idx::<T>::from_raw(RawIdx::from(self.len));
-            self.len += 1;
-            id
-        };
-
-        if let Some(map) = &mut self.map {
-            map.insert(id, value());
-        }
-        id
-    }
-
-    #[allow(dead_code)]
-    pub(crate) fn into_arena(mut self) -> Arena<T> {
-        self.arena.take().unwrap()
-    }
-
-    pub(crate) fn into_map(mut self) -> ArenaMap<Idx<T>, V> {
-        self.map.take().unwrap()
-    }
-}