Ensure const impl cannot coexist with non-const impl

src/test/ui/rfc-2632-const-trait-impl/const-and-non-const-impl.rs

@@ -0,0 +1,33 @@
+#![allow(incomplete_features)]
+#![feature(const_trait_impl)]
+
+pub struct Int(i32);
+
+impl const std::ops::Add for i32 {
+    //~^ ERROR conflicting implementations of trait
+    //~| ERROR only traits defined in the current crate can be implemented for arbitrary types
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        self + rhs
+    }
+}
+
+impl std::ops::Add for Int {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        Int(self.0 + rhs.0)
+    }
+}
+
+impl const std::ops::Add for Int {
+    //~^ ERROR conflicting implementations of trait
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self {
+        Int(self.0 + rhs.0)
+    }
+}
+
+fn main() {}