Add test for const generics struct constructor

Author: varkor

src/test/ui/const-generics/array-wrapper-struct-ctor.rs

@@ -0,0 +1,15 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+struct ArrayStruct<T, const N: usize> {
+    data: [T; N],
+}
+
+struct ArrayTuple<T, const N: usize>([T; N]);
+
+fn main() {
+    let _ = ArrayStruct { data: [0u32; 8] };
+    let _ = ArrayTuple([0u32; 8]);
+}

src/test/ui/const-generics/array-wrapper-struct-ctor.stderr

@@ -0,0 +1,6 @@
+warning: the feature `const_generics` is incomplete and may cause the compiler to crash
+  --> $DIR/array-wrapper-struct-ctor.rs:3:12
+   |
+LL | #![feature(const_generics)]
+   |            ^^^^^^^^^^^^^^
+