tests/codegen/deduced-param-attrs.rs

   1 // compile-flags: -O
   2
   3 #![crate_type = "lib"]
   4 #![allow(incomplete_features)]
   5 #![feature(unsized_locals, unsized_fn_params)]
   6
   7 use std::cell::Cell;
   8 use std::hint;
   9
  10 // Check to make sure that we can deduce the `readonly` attribute from function bodies for
  11 // parameters passed indirectly.
  12
  13 pub struct BigStruct {
  14     blah: [i32; 1024],
  15 }
  16
  17 pub struct BigCellContainer {
  18     blah: [Cell<i32>; 1024],
  19 }
  20
  21 // The by-value parameter for this big struct can be marked readonly.
  22 //
  23 // CHECK: @use_big_struct_immutably({{.*}} readonly {{.*}} %big_struct)
  24 #[no_mangle]
  25 pub fn use_big_struct_immutably(big_struct: BigStruct) {
  26     hint::black_box(&big_struct);
  27 }
  28
  29 // The by-value parameter for this big struct can't be marked readonly, because we mutate it.
  30 //
  31 // CHECK-NOT: @use_big_struct_mutably({{.*}} readonly {{.*}} %big_struct)
  32 #[no_mangle]
  33 pub fn use_big_struct_mutably(mut big_struct: BigStruct) {
  34     big_struct.blah[987] = 654;
  35     hint::black_box(&big_struct);
  36 }
  37
  38 // The by-value parameter for this big struct can't be marked readonly, because it contains
  39 // UnsafeCell.
  40 //
  41 // CHECK-NOT: @use_big_cell_container({{.*}} readonly {{.*}} %big_cell_container)
  42 #[no_mangle]
  43 pub fn use_big_cell_container(big_cell_container: BigCellContainer) {
  44     hint::black_box(&big_cell_container);
  45 }
  46
  47 // Make sure that we don't mistakenly mark a big struct as `readonly` when passed through a generic
  48 // type parameter if it contains UnsafeCell.
  49 //
  50 // CHECK-NOT: @use_something({{.*}} readonly {{.*}} %something)
  51 #[no_mangle]
  52 #[inline(never)]
  53 pub fn use_something<T>(something: T) {
  54     hint::black_box(&something);
  55 }
  56
  57 #[no_mangle]
  58 pub fn forward_big_cell_container(big_cell_container: BigCellContainer) {
  59     use_something(big_cell_container)
  60 }