Merge #9431

9431: internal: Implement TypeRef::ForLifetime r=flodiebold a=Veykril



Co-authored-by: Lukas Wirth <lukastw97@gmail.com>

crates/hir_def/src/item_tree/pretty.rs

@@ -2,6 +2,8 @@
 
 use std::fmt::{self, Write};
 
+use itertools::Itertools;
+
 use crate::{
     attr::RawAttrs,
     generics::{WherePredicate, WherePredicateTypeTarget},
@@ -542,6 +544,10 @@ impl<'a> Printer<'a> {
 
             match bound.as_ref() {
                 TypeBound::Path(path) => self.print_path(path),
+                TypeBound::ForLifetime(lifetimes, path) => {
+                    w!(self, "for<{}> ", lifetimes.iter().format(", "));
+                    self.print_path(path);
+                }
                 TypeBound::Lifetime(lt) => w!(self, "{}", lt.name),
                 TypeBound::Error => w!(self, "{{unknown}}"),
             }

crates/hir_def/src/item_tree/tests.rs

@@ -282,6 +282,7 @@ struct S {
     a: Mixed<'a, T, Item=(), OtherItem=u8>,
     b: <Fully as Qualified>::Syntax,
     c: <TypeAnchored>::Path::<'a>,
+    d: dyn for<'a> Trait<'a>,
 }
         "#,
         expect![[r#"
@@ -289,6 +290,7 @@ struct S {
                 pub(self) a: Mixed<'a, T, Item = (), OtherItem = u8>,
                 pub(self) b: Qualified<Self=Fully>::Syntax,
                 pub(self) c: <TypeAnchored>::Path<'a>,
+                pub(self) d: dyn for<'a> Trait<'a>,
             }
         "#]],
     )
@@ -311,7 +313,7 @@ impl<'a, 'b: 'a, T: Copy + 'a + 'b, const K: u8 = 0> S<'a, 'b, T, K> {
 enum Enum<'a, T, const U: u8> {}
 union Union<'a, T, const U: u8> {}
 
-trait Tr<'a, T: 'a>: Super {}
+trait Tr<'a, T: 'a>: Super where Self: for<'a> Tr<'a, T> {}
         "#,
         expect![[r#"
             pub(self) struct S<'a, 'b, T, const K: u8>
@@ -353,7 +355,8 @@ trait Tr<'a, T: 'a>: Super {}
             pub(self) trait Tr<'a, Self, T>
             where
                 Self: Super,
-                T: 'a
+                T: 'a,
+                Self: for<'a> Tr<'a, T>
             {
             }
         "#]],

crates/hir_def/src/type_ref.rs

@@ -119,7 +119,7 @@ impl LifetimeRef {
 #[derive(Clone, PartialEq, Eq, Hash, Debug)]
 pub enum TypeBound {
     Path(Path),
-    // ForLifetime(Vec<LifetimeRef>, Path), FIXME ForLifetime
+    ForLifetime(Box<[Name]>, Path),
     Lifetime(LifetimeRef),
     Error,
 }
@@ -233,7 +233,9 @@ impl TypeRef {
                 TypeRef::ImplTrait(bounds) | TypeRef::DynTrait(bounds) => {
                     for bound in bounds {
                         match bound.as_ref() {
-                            TypeBound::Path(path) => go_path(path, f),
+                            TypeBound::Path(path) | TypeBound::ForLifetime(_, path) => {
+                                go_path(path, f)
+                            }
                             TypeBound::Lifetime(_) | TypeBound::Error => (),
                         }
                     }
@@ -263,7 +265,9 @@ impl TypeRef {
                         }
                         for bound in &binding.bounds {
                             match bound.as_ref() {
-                                TypeBound::Path(path) => go_path(path, f),
+                                TypeBound::Path(path) | TypeBound::ForLifetime(_, path) => {
+                                    go_path(path, f)
+                                }
                                 TypeBound::Lifetime(_) | TypeBound::Error => (),
                             }
                         }
@@ -287,20 +291,29 @@ pub(crate) fn type_bounds_from_ast(
 
 impl TypeBound {
     pub(crate) fn from_ast(ctx: &LowerCtx, node: ast::TypeBound) -> Self {
+        let lower_path_type = |path_type: ast::PathType| ctx.lower_path(path_type.path()?);
+
         match node.kind() {
             ast::TypeBoundKind::PathType(path_type) => {
-                let path = match path_type.path() {
-                    Some(p) => p,
-                    None => return TypeBound::Error,
-                };
-
-                let path = match ctx.lower_path(path) {
-                    Some(p) => p,
-                    None => return TypeBound::Error,
-                };
-                TypeBound::Path(path)
+                lower_path_type(path_type).map(TypeBound::Path).unwrap_or(TypeBound::Error)
+            }
+            ast::TypeBoundKind::ForType(for_type) => {
+                let lt_refs = match for_type.generic_param_list() {
+                    Some(gpl) => gpl
+                        .lifetime_params()
+                        .flat_map(|lp| lp.lifetime().map(|lt| Name::new_lifetime(&lt)))
+                        .collect(),
+                    None => Box::default(),
+                };
+                let path = for_type.ty().and_then(|ty| match ty {
+                    ast::Type::PathType(path_type) => lower_path_type(path_type),
+                    _ => None,
+                });
+                match path {
+                    Some(p) => TypeBound::ForLifetime(lt_refs, p),
+                    None => TypeBound::Error,
+                }
             }
-            ast::TypeBoundKind::ForType(_) => TypeBound::Error, // FIXME ForType
             ast::TypeBoundKind::Lifetime(lifetime) => {
                 TypeBound::Lifetime(LifetimeRef::new(&lifetime))
             }
@@ -309,8 +322,8 @@ impl TypeBound {
 
     pub fn as_path(&self) -> Option<&Path> {
         match self {
-            TypeBound::Path(p) => Some(p),
-            _ => None,
+            TypeBound::Path(p) | TypeBound::ForLifetime(_, p) => Some(p),
+            TypeBound::Lifetime(_) | TypeBound::Error => None,
         }
     }
 }

crates/hir_ty/src/display.rs

@@ -21,6 +21,7 @@ use hir_def::{
     AssocContainerId, Lookup, ModuleId, TraitId,
 };
 use hir_expand::{hygiene::Hygiene, name::Name};
+use itertools::Itertools;
 
 use crate::{
     const_from_placeholder_idx, db::HirDatabase, from_assoc_type_id, from_foreign_def_id,
@@ -1029,6 +1030,10 @@ impl HirDisplay for TypeBound {
         match self {
             TypeBound::Path(path) => path.hir_fmt(f),
             TypeBound::Lifetime(lifetime) => write!(f, "{}", lifetime.name),
+            TypeBound::ForLifetime(lifetimes, path) => {
+                write!(f, "for<{}> ", lifetimes.iter().format(", "))?;
+                path.hir_fmt(f)
+            }
             TypeBound::Error => write!(f, "{{error}}"),
         }
     }

crates/hir_ty/src/lower.rs

@@ -786,6 +786,11 @@ impl<'a> TyLoweringContext<'a> {
                 bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
                 bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
             }
+            TypeBound::ForLifetime(_, path) => {
+                // FIXME Don't silently drop the hrtb lifetimes here
+                bindings = self.lower_trait_ref_from_path(path, Some(self_ty));
+                bindings.clone().map(WhereClause::Implemented).map(crate::wrap_empty_binders)
+            }
             TypeBound::Lifetime(_) => None,
             TypeBound::Error => None,
         };
@@ -803,7 +808,7 @@ impl<'a> TyLoweringContext<'a> {
         trait_ref: TraitRef,
     ) -> impl Iterator<Item = QuantifiedWhereClause> + 'a {
         let last_segment = match bound {
-            TypeBound::Path(path) => path.segments().last(),
+            TypeBound::Path(path) | TypeBound::ForLifetime(_, path) => path.segments().last(),
             TypeBound::Error | TypeBound::Lifetime(_) => None,
         };
         last_segment

crates/hir_ty/src/tests/display_source_code.rs

@@ -54,3 +54,16 @@ fn main() {
 "#,
     );
 }
+
+#[test]
+fn render_dyn_for_ty() {
+    // FIXME
+    check_types_source_code(
+        r#"
+trait Foo<'a> {}
+
+fn foo(foo: &dyn for<'a> Foo<'a>) {}
+    // ^^^ &dyn Foo
+"#,
+    );
+}