the environment round here is awfully empty

capitalism

src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.rs

@@ -0,0 +1,22 @@
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+
+// This tests that during error handling for the "trait not implemented" error
+// we dont try to evaluate std::mem::size_of::<Self::Assoc> causing an ICE
+
+struct Adt;
+
+trait Foo {
+    type Assoc;
+    fn foo()
+    where
+        [Adt; std::mem::size_of::<Self::Assoc>()]: ,
+    {
+        <[Adt; std::mem::size_of::<Self::Assoc>()] as Foo>::bar()
+        //~^ Error: the trait bound
+    }
+
+    fn bar() {}
+}
+
+fn main() {}

src/test/ui/const-generics/dont-evaluate-array-len-on-err-1.stderr

@@ -0,0 +1,12 @@
+error[E0277]: the trait bound `[Adt; _]: Foo` is not satisfied
+  --> $DIR/dont-evaluate-array-len-on-err-1.rs:15:9
+   |
+LL |         <[Adt; std::mem::size_of::<Self::Assoc>()] as Foo>::bar()
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `Foo` is not implemented for `[Adt; _]`
+...
+LL |     fn bar() {}
+   |     -------- required by `Foo::bar`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.