tests/mir-opt/inline/inline_box_fn.rs

// EMIT_MIR_FOR_EACH_PANIC_STRATEGY
//@ test-mir-pass: Inline
//@ compile-flags: --crate-type=lib

// EMIT_MIR inline_box_fn.call.Inline.diff
fn call(x: Box<dyn Fn(i32)>) {
    // CHECK-LABEL: fn call(
    // CHECK-NOT: inlined
    x(1);
}