Support generic function in generate_function assist

crates/hir-ty/src/lib.rs

@@ -39,11 +39,13 @@ use std::sync::Arc;
 use chalk_ir::{
     fold::{Shift, TypeFoldable},
     interner::HasInterner,
-    NoSolution,
+    visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor},
+    NoSolution, TyData,
 };
 use hir_def::{expr::ExprId, type_ref::Rawness, TypeOrConstParamId};
 use hir_expand::name;
 use itertools::Either;
+use rustc_hash::FxHashSet;
 use traits::FnTrait;
 use utils::Generics;
 
@@ -562,3 +564,68 @@ pub fn callable_sig_from_fnonce(
 
     Some(CallableSig::from_params_and_return(params, ret_ty, false, Safety::Safe))
 }
+
+struct PlaceholderCollector<'db> {
+    db: &'db dyn HirDatabase,
+    placeholders: FxHashSet<TypeOrConstParamId>,
+}
+
+impl PlaceholderCollector<'_> {
+    fn collect(&mut self, idx: PlaceholderIndex) {
+        let id = from_placeholder_idx(self.db, idx);
+        self.placeholders.insert(id);
+    }
+}
+
+impl TypeVisitor<Interner> for PlaceholderCollector<'_> {
+    type BreakTy = ();
+
+    fn as_dyn(&mut self) -> &mut dyn TypeVisitor<Interner, BreakTy = Self::BreakTy> {
+        self
+    }
+
+    fn interner(&self) -> Interner {
+        Interner
+    }
+
+    fn visit_ty(
+        &mut self,
+        ty: &Ty,
+        outer_binder: DebruijnIndex,
+    ) -> std::ops::ControlFlow<Self::BreakTy> {
+        let has_placeholder_bits = TypeFlags::HAS_TY_PLACEHOLDER | TypeFlags::HAS_CT_PLACEHOLDER;
+        let TyData { kind, flags } = ty.data(Interner);
+
+        if let TyKind::Placeholder(idx) = kind {
+            self.collect(*idx);
+        } else if flags.intersects(has_placeholder_bits) {
+            return ty.super_visit_with(self, outer_binder);
+        } else {
+            // Fast path: don't visit inner types (e.g. generic arguments) when `flags` indicate
+            // that there are no placeholders.
+        }
+
+        std::ops::ControlFlow::Continue(())
+    }
+
+    fn visit_const(
+        &mut self,
+        constant: &chalk_ir::Const<Interner>,
+        _outer_binder: DebruijnIndex,
+    ) -> std::ops::ControlFlow<Self::BreakTy> {
+        if let chalk_ir::ConstValue::Placeholder(idx) = constant.data(Interner).value {
+            self.collect(idx);
+        }
+        std::ops::ControlFlow::Continue(())
+    }
+}
+
+/// Returns unique placeholders for types and consts contained in `value`.
+pub fn collect_placeholders<T>(value: &T, db: &dyn HirDatabase) -> Vec<TypeOrConstParamId>
+where
+    T: ?Sized + TypeVisitable<Interner>,
+{
+    let mut collector = PlaceholderCollector { db, placeholders: FxHashSet::default() };
+    value.visit_with(&mut collector, DebruijnIndex::INNERMOST);
+    collector.placeholders.into_iter().collect()
+}

crates/hir/src/lib.rs

@@ -2165,6 +2165,16 @@ impl AsAssocItem for ModuleDef {
         }
     }
 }
+impl AsAssocItem for DefWithBody {
+    fn as_assoc_item(self, db: &dyn HirDatabase) -> Option<AssocItem> {
+        match self {
+            DefWithBody::Function(it) => it.as_assoc_item(db),
+            DefWithBody::Const(it) => it.as_assoc_item(db),
+            DefWithBody::Static(_) | DefWithBody::Variant(_) => None,
+        }
+    }
+}
+
 fn as_assoc_item<ID, DEF, CTOR, AST>(db: &dyn HirDatabase, ctor: CTOR, id: ID) -> Option<AssocItem>
 where
     ID: Lookup<Data = AssocItemLoc<AST>>,
@@ -2560,6 +2570,14 @@ impl GenericParam {
             GenericParam::LifetimeParam(it) => it.name(db),
         }
     }
+
+    pub fn parent(self) -> GenericDef {
+        match self {
+            GenericParam::TypeParam(it) => it.id.parent().into(),
+            GenericParam::ConstParam(it) => it.id.parent().into(),
+            GenericParam::LifetimeParam(it) => it.id.parent.into(),
+        }
+    }
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
@@ -3139,15 +3157,15 @@ impl Type {
     }
 
     pub fn is_closure(&self) -> bool {
-        matches!(&self.ty.kind(Interner), TyKind::Closure { .. })
+        matches!(self.ty.kind(Interner), TyKind::Closure { .. })
     }
 
     pub fn is_fn(&self) -> bool {
-        matches!(&self.ty.kind(Interner), TyKind::FnDef(..) | TyKind::Function { .. })
+        matches!(self.ty.kind(Interner), TyKind::FnDef(..) | TyKind::Function { .. })
     }
 
     pub fn is_array(&self) -> bool {
-        matches!(&self.ty.kind(Interner), TyKind::Array(..))
+        matches!(self.ty.kind(Interner), TyKind::Array(..))
     }
 
     pub fn is_packed(&self, db: &dyn HirDatabase) -> bool {
@@ -3164,7 +3182,7 @@ impl Type {
     }
 
     pub fn is_raw_ptr(&self) -> bool {
-        matches!(&self.ty.kind(Interner), TyKind::Raw(..))
+        matches!(self.ty.kind(Interner), TyKind::Raw(..))
     }
 
     pub fn contains_unknown(&self) -> bool {
@@ -3599,6 +3617,14 @@ impl Type {
             _ => None,
         }
     }
+
+    /// Returns unique `GenericParam`s contained in this type.
+    pub fn generic_params(&self, db: &dyn HirDatabase) -> FxHashSet<GenericParam> {
+        hir_ty::collect_placeholders(&self.ty, db)
+            .into_iter()
+            .map(|id| TypeOrConstParam { id }.split(db).either_into())
+            .collect()
+    }
 }
 
 #[derive(Debug)]

crates/hir/src/semantics.rs

@@ -1319,10 +1319,7 @@ impl<'db> SemanticsImpl<'db> {
         let _p = profile::span("Semantics::analyze_impl");
         let node = self.find_file(node);
 
-        let container = match self.with_ctx(|ctx| ctx.find_container(node)) {
-            Some(it) => it,
-            None => return None,
-        };
+        let container = self.with_ctx(|ctx| ctx.find_container(node))?;
 
         let resolver = match container {
             ChildContainer::DefWithBodyId(def) => {
@@ -1582,7 +1579,7 @@ fn find_root(node: &SyntaxNode) -> SyntaxNode {
     node.ancestors().last().unwrap()
 }
 
-/// `SemanticScope` encapsulates the notion of a scope (the set of visible
+/// `SemanticsScope` encapsulates the notion of a scope (the set of visible
 /// names) at a particular program point.
 ///
 /// It is a bit tricky, as scopes do not really exist inside the compiler.

crates/ide-assists/src/handlers/generate_delegate_methods.rs

@@ -109,7 +109,7 @@ pub(crate) fn generate_delegate_methods(acc: &mut Assists, ctx: &AssistContext<'
                 let tail_expr_finished =
                     if is_async { make::expr_await(tail_expr) } else { tail_expr };
                 let body = make::block_expr([], Some(tail_expr_finished));
-                let f = make::fn_(vis, name, type_params, params, body, ret_type, is_async)
+                let f = make::fn_(vis, name, type_params, None, params, body, ret_type, is_async)
                     .indent(ast::edit::IndentLevel(1))
                     .clone_for_update();