1 files changed, 96 insertions, 0 deletions
diff --git a/src/test/ui/array-slice-vec/subslice-patterns-const-eval-match.rs b/src/test/ui/array-slice-vec/subslice-patterns-const-eval-match.rs
new file mode 100644
index 000000000..5a6283e9f
--- /dev/null
+++ b/src/test/ui/array-slice-vec/subslice-patterns-const-eval-match.rs
@@ -0,0 +1,96 @@
+// 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>);
+}