compiler/rustc_codegen_cranelift/example/subslice-patterns-const-eval.rs

   1 // Based on https://github.com/rust-lang/rust/blob/c5840f9d252c2f5cc16698dbf385a29c5de3ca07/src/test/ui/array-slice-vec/subslice-patterns-const-eval-match.rs
   2
   3 // Test that array subslice patterns are correctly handled in const evaluation.
   4
   5 // run-pass
   6
   7 #[derive(PartialEq, Debug, Clone)]
   8 struct N(u8);
   9
  10 #[derive(PartialEq, Debug, Clone)]
  11 struct Z;
  12
  13 macro_rules! n {
  14     ($($e:expr),* $(,)?) => {
  15         [$(N($e)),*]
  16     }
  17 }
  18
  19 // This macro has an unused variable so that it can be repeated base on the
  20 // number of times a repeated variable (`$e` in `z`) occurs.
  21 macro_rules! zed {
  22     ($e:expr) => { Z }
  23 }
  24
  25 macro_rules! z {
  26     ($($e:expr),* $(,)?) => {
  27         [$(zed!($e)),*]
  28     }
  29 }
  30
  31 // Compare constant evaluation and runtime evaluation of a given expression.
  32 macro_rules! compare_evaluation {
  33     ($e:expr, $t:ty $(,)?) => {{
  34         const CONST_EVAL: $t = $e;
  35         const fn const_eval() -> $t { $e }
  36         static CONST_EVAL2: $t = const_eval();
  37         let runtime_eval = $e;
  38         assert_eq!(CONST_EVAL, runtime_eval);
  39         assert_eq!(CONST_EVAL2, runtime_eval);
  40     }}
  41 }
  42
  43 // Repeat `$test`, substituting the given macro variables with the given
  44 // identifiers.
  45 //
  46 // For example:
  47 //
  48 // repeat! {
  49 //     ($name); X; Y:
  50 //     struct $name;
  51 // }
  52 //
  53 // Expands to:
  54 //
  55 // struct X; struct Y;
  56 //
  57 // This is used to repeat the tests using both the `N` and `Z`
  58 // types.
  59 macro_rules! repeat {
  60     (($($dollar:tt $placeholder:ident)*); $($($values:ident),+);*: $($test:tt)*) => {
  61         macro_rules! single {
  62             ($($dollar $placeholder:ident),*) => { $($test)* }
  63         }
  64         $(single!($($values),+);)*
  65     }
  66 }
  67
  68 fn main() {
  69     repeat! {
  70         ($arr $Ty); n, N; z, Z:
  71         compare_evaluation!({ let [_, x @ .., _] = $arr!(1, 2, 3, 4); x }, [$Ty; 2]);
  72         compare_evaluation!({ let [_, ref x @ .., _] = $arr!(1, 2, 3, 4); x }, &'static [$Ty; 2]);
  73         compare_evaluation!({ let [_, x @ .., _] = &$arr!(1, 2, 3, 4); x }, &'static [$Ty; 2]);
  74
  75         compare_evaluation!({ let [_, _, x @ .., _, _] = $arr!(1, 2, 3, 4); x }, [$Ty; 0]);
  76         compare_evaluation!(
  77             { let [_, _, ref x @ .., _, _] = $arr!(1, 2, 3, 4); x },
  78             &'static [$Ty; 0],
  79         );
  80         compare_evaluation!(
  81             { let [_, _, x @ .., _, _] = &$arr!(1, 2, 3, 4); x },
  82             &'static [$Ty; 0],
  83         );
  84
  85         compare_evaluation!({ let [_, .., x] = $arr!(1, 2, 3, 4); x }, $Ty);
  86         compare_evaluation!({ let [_, .., ref x] = $arr!(1, 2, 3, 4); x }, &'static $Ty);
  87         compare_evaluation!({ let [_, _y @ .., x] = &$arr!(1, 2, 3, 4); x }, &'static $Ty);
  88     }
  89
  90     compare_evaluation!({ let [_, .., N(x)] = n!(1, 2, 3, 4); x }, u8);
  91     compare_evaluation!({ let [_, .., N(ref x)] = n!(1, 2, 3, 4); x }, &'static u8);
  92     compare_evaluation!({ let [_, .., N(x)] = &n!(1, 2, 3, 4); x }, &'static u8);
  93
  94     compare_evaluation!({ let [N(x), .., _] = n!(1, 2, 3, 4); x }, u8);
  95     compare_evaluation!({ let [N(ref x), .., _] = n!(1, 2, 3, 4); x }, &'static u8);
  96     compare_evaluation!({ let [N(x), .., _] = &n!(1, 2, 3, 4); x }, &'static u8);
  97 }