Add regression test for rust-lang#34426

Author: TommasoBianchi

src/test/ui/dropck/dropck_traits.rs

@@ -0,0 +1,48 @@
+// run-pass
+//! Regression test for #34426, regarding HRTB in drop impls
+
+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) {
+        println!("drop with hrtb");
+    }
+}
+
+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) {
+        println!("drop with hrtb");
+    }
+}
+
+fn main() {
+    let _foo = Foo { l: 0 };
+
+    let _bar = Bar { l: 0 };
+}