Add codegen test to be sure we get rid of uneeded clones after monomorphization

Author: spastorino

tests/codegen/ergonomic-clones/closure.rs

@@ -0,0 +1,56 @@
+// ignore-tidy
+//@ compile-flags: -C no-prepopulate-passes -Copt-level=0 -Zmir-opt-level=0
+
+#![crate_type = "lib"]
+
+#![feature(ergonomic_clones)]
+#![allow(incomplete_features)]
+
+use std::clone::UseCloned;
+
+pub fn ergonomic_clone_closure_move() -> String {
+    let s = String::from("hi");
+
+    // CHECK-NOT: ; call core::clone::impls::<impl core::clone::Clone for String>::clone
+    let cl = use || s;
+    cl()
+}
+
+#[derive(Clone)]
+struct Foo;
+
+impl UseCloned for Foo {}
+
+pub fn ergonomic_clone_closure_use_cloned() -> Foo {
+    let f = Foo;
+
+    // CHECK: ; call <closure::Foo as core::clone::Clone>::clone
+    let f1 = use || f;
+
+    // CHECK: ; call <closure::Foo as core::clone::Clone>::clone
+    let f2 = use || f;
+
+    f
+}
+
+pub fn ergonomic_clone_closure_copy() -> i32 {
+    let i = 1;
+
+    // CHECK-NOT: ; call core::clone::impls::<impl core::clone::Clone for i32>::clone
+    let i1 = use || i;
+
+    // CHECK-NOT: ; call core::clone::impls::<impl core::clone::Clone for i32>::clone
+    let i2 = use || i;
+
+    i
+}
+
+pub fn ergonomic_clone_closure_use_cloned_generics<T: UseCloned>(f: T) -> T {
+    // CHECK-NOT: ; call core::clone::impls::<impl core::clone::Clone for i32>::clone
+    let f1 = use || f;
+
+    // CHECK-NOT: ; call core::clone::impls::<impl core::clone::Clone for i32>::clone
+    let f2 = use || f;
+
+    f
+}