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