3 files changed, 12 insertions, 5 deletions
diff --git a/src/doc/reference/src/attributes/testing.md b/src/doc/reference/src/attributes/testing.md
index 63df999ad..2c3b29286 100644
--- a/src/doc/reference/src/attributes/testing.md
+++ b/src/doc/reference/src/attributes/testing.md
@@ -12,9 +12,8 @@ functions are only compiled when in test mode. Test functions must be free,
 monomorphic functions that take no arguments, and the return type must implement the [`Termination`] trait, for example:
 
 * `()`
-* `Result<(), E> where E: Debug`
+* `Result<T, E> where T: Termination, E: Debug`
 * `!`
-<!-- * Result<!, E> where E: Debug` -->
 
 <!-- If the previous section needs updating (from "must take no arguments"
   onwards, also update it in the crates-and-source-files.md file -->
diff --git a/src/doc/reference/src/attributes/type_system.md b/src/doc/reference/src/attributes/type_system.md
index 729069d26..71b0243a6 100644
--- a/src/doc/reference/src/attributes/type_system.md
+++ b/src/doc/reference/src/attributes/type_system.md
@@ -127,6 +127,14 @@ match message {
 }
 ```
 
+It's also not allowed to cast non-exhaustive types from foreign crates.
+```rust, ignore
+use othercrate::NonExhaustiveEnum;
+
+// Cannot cast a non-exhaustive enum outside of its defining crate.
+let _ = NonExhaustiveEnum::default() as u8;
+```
+
 Non-exhaustive types are always considered inhabited in downstream crates.
 
 [_MetaWord_]: ../attributes.md#meta-item-attribute-syntax
diff --git a/src/doc/reference/src/crates-and-source-files.md b/src/doc/reference/src/crates-and-source-files.md
index 6922b0ee3..8d54c3f6b 100644
--- a/src/doc/reference/src/crates-and-source-files.md
+++ b/src/doc/reference/src/crates-and-source-files.md
@@ -123,10 +123,9 @@ fn main() -> impl std::process::Termination {
 >
 > * `()`
 > * [`!`]
+> * [`Infallible`]
 > * [`ExitCode`]
-> * `Result<(), E> where E: Debug`
-> * `Result<Infallible, E> where E: Debug`
-<!-- > * Result<!, E> where E: Debug` -->
+> * `Result<T, E> where T: Termination, E: Debug`
 
 <!-- If the previous section needs updating (from "must take no arguments"
   onwards, also update it in the testing.md file -->
@@ -165,6 +164,7 @@ or `_` (U+005F) characters.
 [_shebang_]: https://en.wikipedia.org/wiki/Shebang_(Unix)
 [_utf8 byte order mark_]: https://en.wikipedia.org/wiki/Byte_order_mark#UTF-8
 [`ExitCode`]: ../std/process/struct.ExitCode.html
+[`Infallible`]: ../std/convert/enum.Infallible.html
 [`Termination`]: ../std/process/trait.Termination.html
 [attribute]: attributes.md
 [attributes]: attributes.md