Rust function parameter via generics

rust_fn_passing_generics.rs

fn foo() -> impl Fn(i32) -> i32 {
    |x| x + 1
}

fn qux<F>(f: F) -> i32
where F: Fn(i32) -> i32 {
    f(10)
}

pub fn main() {
  let f = foo();
  println!("foo()(10):       {}", f(10));
  println!("from qux: f(10): {}", qux(&f));
}

/*
Generated assembly:
-------------------
0000000100004080 <__ZN1x3qux17hec88419833e3d63fE>:
100004080: d100c3ff     sub     sp, sp, #0x30
100004084: a9027bfd     stp     x29, x30, [sp, #0x20]
100004088: 910083fd     add     x29, sp, #0x20
10000408c: aa0003e8     mov     x8, x0
100004090: 910023e0     add     x0, sp, #0x8
100004094: f90007e8     str     x8, [sp, #0x8]
100004098: 52800141     mov     w1, #0xa                ; =10
10000409c: 97ffff92     bl      0x100003ee4 <__ZN4core3ops8function5impls68_$LT$impl$u20$core..ops..function..Fn$LT$A$GT$$u20$for$u20$$RF$F$GT$4call17h6618343c809f89b5E>
1000040a0: b90007e0     str     w0, [sp, #0x4]
1000040a4: 14000007     b       0x1000040c0 <__ZN1x3qux17hec88419833e3d63fE+0x40>
1000040a8: f9400be0     ldr     x0, [sp, #0x10]
1000040ac: 9400d6d9     bl      0x100039c10 <dyld_stub_binder+0x100039c10>
1000040b0: f9000be0     str     x0, [sp, #0x10]
1000040b4: aa0103e8     mov     x8, x1
1000040b8: b9001be8     str     w8, [sp, #0x18]
1000040bc: 17fffffb     b       0x1000040a8 <__ZN1x3qux17hec88419833e3d63fE+0x28>
1000040c0: b94007e0     ldr     w0, [sp, #0x4]
1000040c4: a9427bfd     ldp     x29, x30, [sp, #0x20]
1000040c8: 9100c3ff     add     sp, sp, #0x30
1000040cc: d65f03c0     ret
*/