test for non local anon const printing

Author: BoxyUwU

tests/ui/const-generics/generic_const_exprs/auxiliary/anon_const_non_local.rs

@@ -0,0 +1,8 @@
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+pub struct Foo<const N: usize>;
+
+pub fn foo<const N: usize>() -> Foo<{ N + 1 }> {
+    Foo
+}

tests/ui/const-generics/generic_const_exprs/non_local_anon_const_diagnostics.rs

@@ -0,0 +1,16 @@
+// aux-build:anon_const_non_local.rs
+
+#![feature(generic_const_exprs)]
+#![allow(incomplete_features)]
+
+extern crate anon_const_non_local;
+
+fn bar<const M: usize>()
+where
+    [(); M + 1]:,
+{
+    let _: anon_const_non_local::Foo<2> = anon_const_non_local::foo::<M>();
+    //~^ ERROR: mismatched types
+}
+
+fn main() {}

tests/ui/const-generics/generic_const_exprs/non_local_anon_const_diagnostics.stderr

@@ -0,0 +1,12 @@
+error[E0308]: mismatched types
+  --> $DIR/non_local_anon_const_diagnostics.rs:12:43
+   |
+LL |     let _: anon_const_non_local::Foo<2> = anon_const_non_local::foo::<M>();
+   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `2`, found `_`
+   |
+   = note: expected constant `2`
+              found constant `_`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0308`.