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// Test that slice subslice patterns are correctly handled in const evaluation.
// run-pass
#[derive(PartialEq, Debug, Clone)]
struct N(u8);
#[derive(PartialEq, Debug, Clone)]
struct Z;
macro_rules! n {
($($e:expr),* $(,)?) => {
[$(N($e)),*]
}
}
// This macro has an unused variable so that it can be repeated base on the
// number of times a repeated variable (`$e` in `z`) occurs.
macro_rules! zed {
($e:expr) => { Z }
}
macro_rules! z {
($($e:expr),* $(,)?) => {
[$(zed!($e)),*]
}
}
// Compare constant evaluation and runtime evaluation of a given expression.
macro_rules! compare_evaluation_inner {
($e:expr, $t:ty $(,)?) => {{
const CONST_EVAL: $t = $e;
const fn const_eval() -> $t { $e }
static CONST_EVAL2: $t = const_eval();
let runtime_eval = $e;
assert_eq!(CONST_EVAL, runtime_eval);
assert_eq!(CONST_EVAL2, runtime_eval);
}}
}
// Compare the result of matching `$e` against `$p` using both `if let` and
// `match`.
macro_rules! compare_evaluation {
($p:pat, $e:expr, $matches:expr, $t:ty $(,)?) => {{
compare_evaluation_inner!(if let $p = $e as &[_] { $matches } else { None }, $t);
compare_evaluation_inner!(match $e as &[_] { $p => $matches, _ => None }, $t);
}}
}
// Repeat `$test`, substituting the given macro variables with the given
// identifiers.
//
// For example:
//
// repeat! {
// ($name); X; Y:
// struct $name;
// }
//
// Expands to:
//
// struct X; struct Y;
//
// This is used to repeat the tests using both the `N` and `Z`
// types.
macro_rules! repeat {
(($($dollar:tt $placeholder:ident)*); $($($values:ident),+);*: $($test:tt)*) => {
macro_rules! single {
($($dollar $placeholder:ident),*) => { $($test)* }
}
$(single!($($values),+);)*
}
}
fn main() {
repeat! {
($arr $Ty); n, N; z, Z:
compare_evaluation!([_, x @ .., _], &$arr!(1, 2, 3, 4), Some(x), Option<&'static [$Ty]>);
compare_evaluation!([x, .., _], &$arr!(1, 2, 3, 4), Some(x), Option<&'static $Ty>);
compare_evaluation!([_, .., x], &$arr!(1, 2, 3, 4), Some(x), Option<&'static $Ty>);
compare_evaluation!([_, x @ .., _], &$arr!(1, 2), Some(x), Option<&'static [$Ty]>);
compare_evaluation!([x, .., _], &$arr!(1, 2), Some(x), Option<&'static $Ty>);
compare_evaluation!([_, .., x], &$arr!(1, 2), Some(x), Option<&'static $Ty>);
compare_evaluation!([_, x @ .., _], &$arr!(1), Some(x), Option<&'static [$Ty]>);
compare_evaluation!([x, .., _], &$arr!(1), Some(x), Option<&'static $Ty>);
compare_evaluation!([_, .., x], &$arr!(1), Some(x), Option<&'static $Ty>);
}
compare_evaluation!([N(x), .., _], &n!(1, 2, 3, 4), Some(x), Option<&'static u8>);
compare_evaluation!([_, .., N(x)], &n!(1, 2, 3, 4), Some(x), Option<&'static u8>);
compare_evaluation!([N(x), .., _], &n!(1, 2), Some(x), Option<&'static u8>);
compare_evaluation!([_, .., N(x)], &n!(1, 2), Some(x), Option<&'static u8>);
}
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