Auto merge of #14001 - Veykril:lang-item, r=Veykril

Replace SmolStr usage with lang item enum for lang items

Fixes rust-lang/rust-analyzer#13395

Author: bors

crates/hir-def/src/db.rs

@@ -6,7 +6,7 @@ use either::Either;
 use hir_expand::{db::AstDatabase, HirFileId};
 use intern::Interned;
 use la_arena::ArenaMap;
-use syntax::{ast, AstPtr, SmolStr};
+use syntax::{ast, AstPtr};
 
 use crate::{
     adt::{EnumData, StructData},
@@ -19,7 +19,7 @@ use crate::{
     generics::GenericParams,
     import_map::ImportMap,
     item_tree::{AttrOwner, ItemTree},
-    lang_item::{LangItemTarget, LangItems},
+    lang_item::{LangItem, LangItemTarget, LangItems},
     nameres::{diagnostics::DefDiagnostic, DefMap},
     visibility::{self, Visibility},
     AttrDefId, BlockId, BlockLoc, ConstId, ConstLoc, DefWithBodyId, EnumId, EnumLoc, ExternBlockId,
@@ -183,7 +183,7 @@ pub trait DefDatabase: InternDatabase + AstDatabase + Upcast<dyn AstDatabase> {
     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>;
+    fn lang_item(&self, start_crate: CrateId, item: LangItem) -> Option<LangItemTarget>;
 
     #[salsa::invoke(ImportMap::import_map_query)]
     fn import_map(&self, krate: CrateId) -> Arc<ImportMap>;

crates/hir-def/src/lang_item.rs

@@ -133,6 +133,14 @@ impl Name {
         }
     }
 
+    /// Returns the text this name represents if it isn't a tuple field.
+    pub fn as_str(&self) -> Option<&str> {
+        match &self.0 {
+            Repr::Text(it) => Some(it),
+            _ => None,
+        }
+    }
+
     /// Returns the textual representation of this name as a [`SmolStr`].
     /// Prefer using this over [`ToString::to_string`] if possible as this conversion is cheaper in
     /// the general case.

crates/hir-expand/src/name.rs

@@ -6,9 +6,9 @@
 use std::sync::Arc;
 
 use chalk_ir::cast::Cast;
+use hir_def::lang_item::LangItem;
 use hir_expand::name::name;
 use limit::Limit;
-use syntax::SmolStr;
 
 use crate::{
     db::HirDatabase, infer::unify::InferenceTable, Canonical, Goal, Interner, ProjectionTyExt,
@@ -117,9 +117,8 @@ fn deref_by_trait(table: &mut InferenceTable<'_>, ty: Ty) -> Option<Ty> {
     }
 
     let db = table.db;
-    let deref_trait = db
-        .lang_item(table.trait_env.krate, SmolStr::new_inline("deref"))
-        .and_then(|l| l.as_trait())?;
+    let deref_trait =
+        db.lang_item(table.trait_env.krate, LangItem::Deref).and_then(|l| l.as_trait())?;
     let target = db.trait_data(deref_trait).associated_type_by_name(&name![Target])?;
 
     let projection = {

crates/hir-ty/src/autoderef.rs

@@ -3,7 +3,6 @@
 use std::sync::Arc;
 
 use cov_mark::hit;
-use syntax::SmolStr;
 use tracing::debug;
 
 use chalk_ir::{cast::Cast, fold::shift::Shift, CanonicalVarKinds};
@@ -12,7 +11,7 @@ use chalk_solve::rust_ir::{self, OpaqueTyDatumBound, WellKnownTrait};
 use base_db::CrateId;
 use hir_def::{
     expr::Movability,
-    lang_item::{lang_attr, LangItemTarget},
+    lang_item::{lang_attr, LangItem, LangItemTarget},
     AssocItemId, GenericDefId, HasModule, ItemContainerId, Lookup, ModuleId, TypeAliasId,
 };
 use hir_expand::name::name;
@@ -182,9 +181,9 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
         &self,
         well_known_trait: rust_ir::WellKnownTrait,
     ) -> Option<chalk_ir::TraitId<Interner>> {
-        let lang_attr = lang_attr_from_well_known_trait(well_known_trait);
+        let lang_attr = lang_item_from_well_known_trait(well_known_trait);
         let trait_ = match self.db.lang_item(self.krate, lang_attr.into()) {
-            Some(LangItemTarget::TraitId(trait_)) => trait_,
+            Some(LangItemTarget::Trait(trait_)) => trait_,
             _ => return None,
         };
         Some(to_chalk_trait_id(trait_))
@@ -216,7 +215,7 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
             crate::ImplTraitId::AsyncBlockTypeImplTrait(..) => {
                 if let Some((future_trait, future_output)) = self
                     .db
-                    .lang_item(self.krate, SmolStr::new_inline("future_trait"))
+                    .lang_item(self.krate, LangItem::Future)
                     .and_then(|item| item.as_trait())
                     .and_then(|trait_| {
                         let alias =
@@ -246,7 +245,7 @@ impl<'a> chalk_solve::RustIrDatabase<Interner> for ChalkContext<'a> {
                     binder.push(crate::wrap_empty_binders(impl_bound));
                     let sized_trait = self
                         .db
-                        .lang_item(self.krate, SmolStr::new_inline("sized"))
+                        .lang_item(self.krate, LangItem::Sized)
                         .and_then(|item| item.as_trait());
                     if let Some(sized_trait_) = sized_trait {
                         let sized_bound = WhereClause::Implemented(TraitRef {
@@ -493,7 +492,7 @@ pub(crate) fn associated_ty_data_query(
 
     if !ctx.unsized_types.borrow().contains(&self_ty) {
         let sized_trait = db
-            .lang_item(resolver.krate(), SmolStr::new_inline("sized"))
+            .lang_item(resolver.krate(), LangItem::Sized)
             .and_then(|lang_item| lang_item.as_trait().map(to_chalk_trait_id));
         let sized_bound = sized_trait.into_iter().map(|sized_trait| {
             let trait_bound =
@@ -541,8 +540,8 @@ pub(crate) fn trait_datum_query(
     let where_clauses = convert_where_clauses(db, trait_.into(), &bound_vars);
     let associated_ty_ids = trait_data.associated_types().map(to_assoc_type_id).collect();
     let trait_datum_bound = rust_ir::TraitDatumBound { where_clauses };
-    let well_known =
-        lang_attr(db.upcast(), trait_).and_then(|name| well_known_trait_from_lang_attr(&name));
+    let well_known = lang_attr(db.upcast(), trait_)
+        .and_then(|name| well_known_trait_from_lang_item(LangItem::from_str(&name)?));
     let trait_datum = TraitDatum {
         id: trait_id,
         binders: make_binders(db, &generic_params, trait_datum_bound),
@@ -553,42 +552,42 @@ pub(crate) fn trait_datum_query(
     Arc::new(trait_datum)
 }
 
-fn well_known_trait_from_lang_attr(name: &str) -> Option<WellKnownTrait> {
-    Some(match name {
-        "clone" => WellKnownTrait::Clone,
-        "coerce_unsized" => WellKnownTrait::CoerceUnsized,
-        "copy" => WellKnownTrait::Copy,
-        "discriminant_kind" => WellKnownTrait::DiscriminantKind,
-        "dispatch_from_dyn" => WellKnownTrait::DispatchFromDyn,
-        "drop" => WellKnownTrait::Drop,
-        "fn" => WellKnownTrait::Fn,
-        "fn_mut" => WellKnownTrait::FnMut,
-        "fn_once" => WellKnownTrait::FnOnce,
-        "generator" => WellKnownTrait::Generator,
-        "sized" => WellKnownTrait::Sized,
-        "unpin" => WellKnownTrait::Unpin,
-        "unsize" => WellKnownTrait::Unsize,
-        "tuple_trait" => WellKnownTrait::Tuple,
+fn well_known_trait_from_lang_item(item: LangItem) -> Option<WellKnownTrait> {
+    Some(match item {
+        LangItem::Clone => WellKnownTrait::Clone,
+        LangItem::CoerceUnsized => WellKnownTrait::CoerceUnsized,
+        LangItem::Copy => WellKnownTrait::Copy,
+        LangItem::DiscriminantKind => WellKnownTrait::DiscriminantKind,
+        LangItem::DispatchFromDyn => WellKnownTrait::DispatchFromDyn,
+        LangItem::Drop => WellKnownTrait::Drop,
+        LangItem::Fn => WellKnownTrait::Fn,
+        LangItem::FnMut => WellKnownTrait::FnMut,
+        LangItem::FnOnce => WellKnownTrait::FnOnce,
+        LangItem::Generator => WellKnownTrait::Generator,
+        LangItem::Sized => WellKnownTrait::Sized,
+        LangItem::Unpin => WellKnownTrait::Unpin,
+        LangItem::Unsize => WellKnownTrait::Unsize,
+        LangItem::Tuple => WellKnownTrait::Tuple,
         _ => return None,
     })
 }
 
-fn lang_attr_from_well_known_trait(attr: WellKnownTrait) -> &'static str {
-    match attr {
-        WellKnownTrait::Clone => "clone",
-        WellKnownTrait::CoerceUnsized => "coerce_unsized",
-        WellKnownTrait::Copy => "copy",
-        WellKnownTrait::DiscriminantKind => "discriminant_kind",
-        WellKnownTrait::DispatchFromDyn => "dispatch_from_dyn",
-        WellKnownTrait::Drop => "drop",
-        WellKnownTrait::Fn => "fn",
-        WellKnownTrait::FnMut => "fn_mut",
-        WellKnownTrait::FnOnce => "fn_once",
-        WellKnownTrait::Generator => "generator",
-        WellKnownTrait::Sized => "sized",
-        WellKnownTrait::Tuple => "tuple_trait",
-        WellKnownTrait::Unpin => "unpin",
-        WellKnownTrait::Unsize => "unsize",
+fn lang_item_from_well_known_trait(trait_: WellKnownTrait) -> LangItem {
+    match trait_ {
+        WellKnownTrait::Clone => LangItem::Clone,
+        WellKnownTrait::CoerceUnsized => LangItem::CoerceUnsized,
+        WellKnownTrait::Copy => LangItem::Copy,
+        WellKnownTrait::DiscriminantKind => LangItem::DiscriminantKind,
+        WellKnownTrait::DispatchFromDyn => LangItem::DispatchFromDyn,
+        WellKnownTrait::Drop => LangItem::Drop,
+        WellKnownTrait::Fn => LangItem::Fn,
+        WellKnownTrait::FnMut => LangItem::FnMut,
+        WellKnownTrait::FnOnce => LangItem::FnOnce,
+        WellKnownTrait::Generator => LangItem::Generator,
+        WellKnownTrait::Sized => LangItem::Sized,
+        WellKnownTrait::Tuple => LangItem::Tuple,
+        WellKnownTrait::Unpin => LangItem::Unpin,
+        WellKnownTrait::Unsize => LangItem::Unsize,
     }
 }
 

crates/hir-ty/src/chalk_db.rs

@@ -4,10 +4,10 @@ use chalk_ir::{FloatTy, IntTy, Mutability, Scalar, TyVariableKind, UintTy};
 use hir_def::{
     builtin_type::{BuiltinFloat, BuiltinInt, BuiltinType, BuiltinUint},
     generics::TypeOrConstParamData,
+    lang_item::LangItem,
     type_ref::Rawness,
     FunctionId, GenericDefId, HasModule, ItemContainerId, Lookup, TraitId,
 };
-use syntax::SmolStr;
 
 use crate::{
     db::HirDatabase, from_assoc_type_id, from_chalk_trait_id, from_foreign_def_id,
@@ -214,9 +214,8 @@ impl TyExt for Ty {
                 match db.lookup_intern_impl_trait_id((*opaque_ty_id).into()) {
                     ImplTraitId::AsyncBlockTypeImplTrait(def, _expr) => {
                         let krate = def.module(db.upcast()).krate();
-                        if let Some(future_trait) = db
-                            .lang_item(krate, SmolStr::new_inline("future_trait"))
-                            .and_then(|item| item.as_trait())
+                        if let Some(future_trait) =
+                            db.lang_item(krate, LangItem::Future).and_then(|item| item.as_trait())
                         {
                             // This is only used by type walking.
                             // Parameters will be walked outside, and projection predicate is not used.

crates/hir-ty/src/chalk_ext.rs

@@ -5,7 +5,9 @@
 use std::fmt;
 use std::sync::Arc;
 
-use hir_def::{path::path, resolver::HasResolver, AdtId, AssocItemId, DefWithBodyId, HasModule};
+use hir_def::lang_item::LangItem;
+use hir_def::{resolver::HasResolver, AdtId, AssocItemId, DefWithBodyId, HasModule};
+use hir_def::{ItemContainerId, Lookup};
 use hir_expand::name;
 use itertools::Either;
 use itertools::Itertools;
@@ -245,26 +247,25 @@ struct FilterMapNextChecker {
 impl FilterMapNextChecker {
     fn new(resolver: &hir_def::resolver::Resolver, db: &dyn HirDatabase) -> Self {
         // Find and store the FunctionIds for Iterator::filter_map and Iterator::next
-        let iterator_path = path![core::iter::Iterator];
-        let mut filter_map_function_id = None;
-        let mut next_function_id = None;
-
-        if let Some(iterator_trait_id) = resolver.resolve_known_trait(db.upcast(), &iterator_path) {
-            let iterator_trait_items = &db.trait_data(iterator_trait_id).items;
-            for item in iterator_trait_items.iter() {
-                if let (name, AssocItemId::FunctionId(id)) = item {
-                    if *name == name![filter_map] {
-                        filter_map_function_id = Some(*id);
+        let (next_function_id, filter_map_function_id) = match db
+            .lang_item(resolver.krate(), LangItem::IteratorNext)
+            .and_then(|it| it.as_function())
+        {
+            Some(next_function_id) => (
+                Some(next_function_id),
+                match next_function_id.lookup(db.upcast()).container {
+                    ItemContainerId::TraitId(iterator_trait_id) => {
+                        let iterator_trait_items = &db.trait_data(iterator_trait_id).items;
+                        iterator_trait_items.iter().find_map(|(name, it)| match it {
+                            &AssocItemId::FunctionId(id) if *name == name![filter_map] => Some(id),
+                            _ => None,
+                        })
                     }
-                    if *name == name![next] {
-                        next_function_id = Some(*id);
-                    }
-                }
-                if filter_map_function_id.is_some() && next_function_id.is_some() {
-                    break;
-                }
-            }
-        }
+                    _ => None,
+                },
+            ),
+            None => (None, None),
+        };
         Self { filter_map_function_id, next_function_id, prev_filter_map_expr_id: None }
     }
 

crates/hir-ty/src/diagnostics/expr.rs

@@ -12,6 +12,7 @@ use hir_def::{
     find_path,
     generics::{TypeOrConstParamData, TypeParamProvenance},
     item_scope::ItemInNs,
+    lang_item::LangItem,
     path::{Path, PathKind},
     type_ref::{ConstScalar, TraitBoundModifier, TypeBound, TypeRef},
     visibility::Visibility,
@@ -21,7 +22,6 @@ use hir_expand::{hygiene::Hygiene, name::Name};
 use intern::{Internable, Interned};
 use itertools::Itertools;
 use smallvec::SmallVec;
-use syntax::SmolStr;
 
 use crate::{
     db::HirDatabase,
@@ -925,7 +925,7 @@ impl SizedByDefault {
             Self::NotSized => false,
             Self::Sized { anchor } => {
                 let sized_trait = db
-                    .lang_item(anchor, SmolStr::new_inline("sized"))
+                    .lang_item(anchor, LangItem::Sized)
                     .and_then(|lang_item| lang_item.as_trait());
                 Some(trait_) == sized_trait
             }
@@ -1057,8 +1057,7 @@ fn write_bounds_like_dyn_trait(
     }
     if let SizedByDefault::Sized { anchor } = default_sized {
         let sized_trait =
-            f.db.lang_item(anchor, SmolStr::new_inline("sized"))
-                .and_then(|lang_item| lang_item.as_trait());
+            f.db.lang_item(anchor, LangItem::Sized).and_then(|lang_item| lang_item.as_trait());
         if !is_sized {
             if !first {
                 write!(f, " + ")?;