Implement TypeRef::ForLifetime

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
+"#,
+    );
+}