Add regression tests

src/test/ui/dropck/dropck_fn_type.rs

@@ -0,0 +1,20 @@
+// run-pass
+//! Regression test for #58311, regarding the usage of Fn types in drop impls
+
+// All of this Drop impls should compile.
+
+#[allow(dead_code)]
+struct S<F: Fn() -> [u8; 1]>(F);
+
+impl<F: Fn() -> [u8; 1]> Drop for S<F> {
+    fn drop(&mut self) {}
+}
+
+#[allow(dead_code)]
+struct P<A, F: FnOnce() -> [A; 10]>(F);
+
+impl<A, F: FnOnce() -> [A; 10]> Drop for P<A, F> {
+    fn drop(&mut self) {}
+}
+
+fn main() {}

src/test/ui/dropck/dropck_traits.rs

@@ -0,0 +1,68 @@
+// run-pass
+//! Regression test for #34426, regarding HRTB in drop impls
+
+// All of this Drop impls should compile.
+
+pub trait Lifetime<'a> {}
+impl<'a> Lifetime<'a> for i32 {}
+
+#[allow(dead_code)]
+struct Foo<L>
+where
+    for<'a> L: Lifetime<'a>,
+{
+    l: L,
+}
+
+impl<L> Drop for Foo<L>
+where
+    for<'a> L: Lifetime<'a>,
+{
+    fn drop(&mut self) {}
+}
+
+#[allow(dead_code)]
+struct Foo2<L>
+where
+    for<'a> L: Lifetime<'a>,
+{
+    l: L,
+}
+
+impl<T: for<'a> Lifetime<'a>> Drop for Foo2<T>
+where
+    for<'x> T: Lifetime<'x>,
+{
+    fn drop(&mut self) {}
+}
+
+pub trait Lifetime2<'a, 'b> {}
+impl<'a, 'b> Lifetime2<'a, 'b> for i32 {}
+
+#[allow(dead_code)]
+struct Bar<L>
+where
+    for<'a, 'b> L: Lifetime2<'a, 'b>,
+{
+    l: L,
+}
+
+impl<L> Drop for Bar<L>
+where
+    for<'a, 'b> L: Lifetime2<'a, 'b>,
+{
+    fn drop(&mut self) {}
+}
+
+#[allow(dead_code)]
+struct FnHolder<T: for<'a> Fn(&'a T, dyn for<'b> Lifetime2<'a, 'b>) -> u8>(T);
+
+impl<T: for<'a> Fn(&'a T, dyn for<'b> Lifetime2<'a, 'b>) -> u8> Drop for FnHolder<T> {
+    fn drop(&mut self) {}
+}
+
+fn main() {
+    let _foo = Foo { l: 0 };
+
+    let _bar = Bar { l: 0 };
+}