Add test for condition in trait const param

Author: varkor

src/test/ui/const-generics/condition-in-trait-const-arg.rs

@@ -0,0 +1,10 @@
+// run-pass
+
+#![feature(const_generics)]
+//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
+
+trait IsZeroTrait<const IS_ZERO: bool>{}
+
+impl IsZeroTrait<{0u8 == 0u8}> for () {}
+
+fn main() {}

src/test/ui/const-generics/condition-in-trait-const-arg.stderr

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