Merge #1154

1154: Initial support for lang items (and str completion) r=flodiebold a=marcogroppo

This PR adds partial support for lang items.
For now, the only supported lang items are the ones that target an impl block.

Lang items are now resolved during type inference - this means that `str` completion now works.

Fixes #1139.

(thanks Florian Diebold for the help!)


Co-authored-by: Marco Groppo <[email protected]>

7 files changed, 144 insertions, 7 deletions

diff --git a/crates/ra_hir/src/db.rs b/crates/ra_hir/src/db.rs
index 18627bbc2..8af0a3176 100644
--- a/crates/ra_hir/src/db.rs
+++ b/crates/ra_hir/src/db.rs
@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use ra_syntax::{SyntaxNode, TreeArc, SourceFile, ast};
+use ra_syntax::{SyntaxNode, TreeArc, SourceFile, SmolStr, ast};
 use ra_db::{SourceDatabase, salsa};
 
 use crate::{
@@ -16,6 +16,7 @@ use crate::{
     generics::{GenericParams, GenericDef},
     type_ref::TypeRef,
     traits::TraitData, Trait, ty::TraitRef,
+    lang_item::{LangItems, LangItemTarget},
     ids
 };
 
@@ -100,6 +101,12 @@ pub trait DefDatabase: SourceDatabase {
 
     #[salsa::invoke(crate::ConstSignature::static_signature_query)]
     fn static_signature(&self, konst: Static) -> Arc<ConstSignature>;
+
+    #[salsa::invoke(crate::lang_item::LangItems::lang_items_query)]
+    fn lang_items(&self, krate: Crate) -> Arc<LangItems>;
+
+    #[salsa::invoke(crate::lang_item::LangItems::lang_item_query)]
+    fn lang_item(&self, start_crate: Crate, item: SmolStr) -> Option<LangItemTarget>;
 }
 
 #[salsa::query_group(HirDatabaseStorage)]
diff --git a/crates/ra_hir/src/lang_item.rs b/crates/ra_hir/src/lang_item.rs
new file mode 100644
index 000000000..5f3f91cba
--- /dev/null
+++ b/crates/ra_hir/src/lang_item.rs
@@ -0,0 +1,102 @@
+use std::sync::Arc;
+use rustc_hash::FxHashMap;
+
+use ra_syntax::{SmolStr, ast::AttrsOwner};
+
+use crate::{
+    Crate, DefDatabase, Enum, Function, HirDatabase, 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> {
+        match self {
+            LangItemTarget::Enum(e) => e.module(db).krate(db),
+            LangItemTarget::Function(f) => f.module(db).krate(db),
+            LangItemTarget::ImplBlock(i) => i.module().krate(db),
+            LangItemTarget::Static(s) => s.module(db).krate(db),
+            LangItemTarget::Struct(s) => s.module(db).krate(db),
+            LangItemTarget::Trait(t) => t.module(db).krate(db),
+        }
+    }
+}
+
+#[derive(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 lang_items_query(db: &impl DefDatabase, krate: Crate) -> Arc<LangItems> {
+        let mut lang_items = LangItems { items: FxHashMap::default() };
+
+        if let Some(module) = krate.root_module(db) {
+            lang_items.collect_lang_items_recursive(db, &module);
+        }
+
+        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.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_recursive(&mut self, db: &impl DefDatabase, module: &Module) {
+        // Look for impl targets
+        let (impl_blocks, source_map) = db.impls_in_module_with_source_map(module.clone());
+        let source = module.definition_source(db).1;
+        for (impl_id, _) in impl_blocks.impls.iter() {
+            let impl_block = source_map.get(&source, impl_id);
+            let lang_item_name = impl_block
+                .attrs()
+                .filter_map(|a| a.as_key_value())
+                .filter(|(key, _)| key == "lang")
+                .map(|(_, val)| val)
+                .nth(0);
+            if let Some(lang_item_name) = lang_item_name {
+                let imp = ImplBlock::from_id(*module, impl_id);
+                self.items.entry(lang_item_name).or_insert(LangItemTarget::ImplBlock(imp));
+            }
+        }
+
+        // FIXME we should look for the other lang item targets (traits, structs, ...)
+
+        // Look for lang items in the children
+        for child in module.children(db) {
+            self.collect_lang_items_recursive(db, &child);
+        }
+    }
+}
diff --git a/crates/ra_hir/src/lib.rs b/crates/ra_hir/src/lib.rs
index 9292de1b5..4411715de 100644
--- a/crates/ra_hir/src/lib.rs
+++ b/crates/ra_hir/src/lib.rs
@@ -36,6 +36,7 @@ mod type_ref;
 mod ty;
 mod impl_block;
 mod expr;
+mod lang_item;
 mod generics;
 mod docs;
 mod resolve;
diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 0eddfab12..39152360c 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -202,6 +202,10 @@ impl CrateDefMap {
         Arc::new(def_map)
     }
 
+    pub(crate) fn krate(&self) -> Crate {
+        self.krate
+    }
+
     pub(crate) fn root(&self) -> CrateModuleId {
         self.root
     }
diff --git a/crates/ra_hir/src/resolve.rs b/crates/ra_hir/src/resolve.rs
index 685f4b8b1..f2c85eb66 100644
--- a/crates/ra_hir/src/resolve.rs
+++ b/crates/ra_hir/src/resolve.rs
@@ -5,13 +5,15 @@ use rustc_hash::FxHashMap;
 
 use crate::{
     ModuleDef,
+    code_model_api::Crate,
     db::HirDatabase,
     name::{Name, KnownName},
     nameres::{PerNs, CrateDefMap, CrateModuleId},
     generics::GenericParams,
     expr::{scope::{ExprScopes, ScopeId}, PatId},
     impl_block::ImplBlock,
-    path::Path, Trait
+    path::Path,
+    Trait
 };
 
 #[derive(Debug, Clone, Default)]
@@ -197,6 +199,10 @@ impl Resolver {
             _ => None,
         })
     }
+
+    pub(crate) fn krate(&self) -> Option<Crate> {
+        self.module().map(|t| t.0.krate())
+    }
 }
 
 impl Resolver {
diff --git a/crates/ra_hir/src/ty/infer.rs b/crates/ra_hir/src/ty/infer.rs
index 7ca1ff595..c7772a7f6 100644
--- a/crates/ra_hir/src/ty/infer.rs
+++ b/crates/ra_hir/src/ty/infer.rs
@@ -462,6 +462,7 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
         let remaining_index = remaining_index.unwrap_or(path.segments.len());
         let mut actual_def_ty: Option<Ty> = None;
 
+        let krate = resolver.krate()?;
         // resolve intermediate segments
         for (i, segment) in path.segments[remaining_index..].iter().enumerate() {
             let ty = match resolved {
@@ -500,9 +501,10 @@ impl<'a, D: HirDatabase> InferenceContext<'a, D> {
             // Attempt to find an impl_item for the type which has a name matching
             // the current segment
             log::debug!("looking for path segment: {:?}", segment);
+
             actual_def_ty = Some(ty.clone());
 
-            let item: crate::ModuleDef = ty.iterate_impl_items(self.db, |item| {
+            let item: crate::ModuleDef = ty.iterate_impl_items(self.db, krate, |item| {
                 let matching_def: Option<crate::ModuleDef> = match item {
                     crate::ImplItem::Method(func) => {
                         let sig = func.signature(self.db);
diff --git a/crates/ra_hir/src/ty/method_resolution.rs b/crates/ra_hir/src/ty/method_resolution.rs
index 667b66095..ea6e0dc0f 100644
--- a/crates/ra_hir/src/ty/method_resolution.rs
+++ b/crates/ra_hir/src/ty/method_resolution.rs
@@ -14,6 +14,7 @@ use crate::{
     resolve::Resolver,
     traits::TraitItem,
     generics::HasGenericParams,
+    ty::primitive::{UncertainIntTy, UncertainFloatTy}
 };
 use super::{TraitRef, Substs};
 
@@ -110,10 +111,19 @@ impl CrateImplBlocks {
     }
 }
 
-fn def_crate(db: &impl HirDatabase, ty: &Ty) -> Option<Crate> {
+fn def_crate(db: &impl HirDatabase, cur_crate: Crate, ty: &Ty) -> Option<Crate> {
     match ty {
         Ty::Apply(a_ty) => match a_ty.ctor {
             TypeCtor::Adt(def_id) => def_id.krate(db),
+            TypeCtor::Bool => db.lang_item(cur_crate, "bool".into())?.krate(db),
+            TypeCtor::Char => db.lang_item(cur_crate, "char".into())?.krate(db),
+            TypeCtor::Float(UncertainFloatTy::Known(f)) => {
+                db.lang_item(cur_crate, f.ty_to_string().into())?.krate(db)
+            }
+            TypeCtor::Int(UncertainIntTy::Known(i)) => {
+                db.lang_item(cur_crate, i.ty_to_string().into())?.krate(db)
+            }
+            TypeCtor::Str => db.lang_item(cur_crate, "str".into())?.krate(db),
             _ => None,
         },
         _ => None,
@@ -150,8 +160,11 @@ impl Ty {
         // find in the end takes &self, we still do the autoderef step (just as
         // rustc does an autoderef and then autoref again).
 
+        let krate = resolver.krate()?;
         for derefed_ty in self.autoderef(db) {
-            if let Some(result) = derefed_ty.iterate_inherent_methods(db, name, &mut callback) {
+            if let Some(result) =
+                derefed_ty.iterate_inherent_methods(db, name, krate, &mut callback)
+            {
                 return Some(result);
             }
             if let Some(result) =
@@ -208,9 +221,10 @@ impl Ty {
         &self,
         db: &impl HirDatabase,
         name: Option<&Name>,
+        krate: Crate,
         mut callback: impl FnMut(&Ty, Function) -> Option<T>,
     ) -> Option<T> {
-        let krate = match def_crate(db, self) {
+        let krate = match def_crate(db, krate, self) {
             Some(krate) => krate,
             None => return None,
         };
@@ -239,9 +253,10 @@ impl Ty {
     pub fn iterate_impl_items<T>(
         self,
         db: &impl HirDatabase,
+        krate: Crate,
         mut callback: impl FnMut(ImplItem) -> Option<T>,
     ) -> Option<T> {
-        let krate = def_crate(db, &self)?;
+        let krate = def_crate(db, krate, &self)?;
         let impls = db.impls_in_crate(krate);
 
         for impl_block in impls.lookup_impl_blocks(&self) {