support const_evaluatable_checked across crate boundaries

src/test/ui/const-generics/const_evaluatable_checked/auxiliary/const_evaluatable_lib.rs

@@ -0,0 +1,9 @@
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+
+pub fn test1<T>() -> [u8; std::mem::size_of::<T>() - 1]
+where
+    [u8; std::mem::size_of::<T>() - 1]: Sized,
+{
+    [0; std::mem::size_of::<T>() - 1]
+}

src/test/ui/const-generics/const_evaluatable_checked/cross_crate.rs

@@ -0,0 +1,15 @@
+// aux-build:const_evaluatable_lib.rs
+// run-pass
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+extern crate const_evaluatable_lib;
+
+fn user<T>() where [u8; std::mem::size_of::<T>() - 1]: Sized {
+    assert_eq!(const_evaluatable_lib::test1::<T>(), [0; std::mem::size_of::<T>() - 1]);
+}
+
+fn main() {
+    assert_eq!(const_evaluatable_lib::test1::<u32>(), [0; 3]);
+    user::<u32>();
+    user::<u64>();
+}

src/test/ui/const-generics/const_evaluatable_checked/cross_crate_predicate.rs

@@ -0,0 +1,13 @@
+// aux-build:const_evaluatable_lib.rs
+#![feature(const_generics, const_evaluatable_checked)]
+#![allow(incomplete_features)]
+extern crate const_evaluatable_lib;
+
+fn user<T>() {
+    let _ = const_evaluatable_lib::test1::<T>();
+    //~^ ERROR constant expression depends
+    //~| ERROR constant expression depends
+    //~| ERROR constant expression depends
+}
+
+fn main() {}

src/test/ui/const-generics/const_evaluatable_checked/cross_crate_predicate.stderr

@@ -0,0 +1,36 @@
+error: constant expression depends on a generic parameter
+  --> $DIR/cross_crate_predicate.rs:7:13
+   |
+LL |     let _ = const_evaluatable_lib::test1::<T>();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | 
+  ::: $DIR/auxiliary/const_evaluatable_lib.rs:6:41
+   |
+LL |     [u8; std::mem::size_of::<T>() - 1]: Sized,
+   |                                         ----- required by this bound in `test1`
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: constant expression depends on a generic parameter
+  --> $DIR/cross_crate_predicate.rs:7:13
+   |
+LL |     let _ = const_evaluatable_lib::test1::<T>();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | 
+  ::: $DIR/auxiliary/const_evaluatable_lib.rs:6:41
+   |
+LL |     [u8; std::mem::size_of::<T>() - 1]: Sized,
+   |                                         ----- required by this bound in `test1::{{constant}}#1`
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: constant expression depends on a generic parameter
+  --> $DIR/cross_crate_predicate.rs:7:13
+   |
+LL |     let _ = const_evaluatable_lib::test1::<T>();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this may fail depending on what value the parameter takes
+
+error: aborting due to 3 previous errors
+