modify intrinsic doc-comment as well

library/core/src/intrinsics.rs

@@ -2662,18 +2662,21 @@ extern "rust-intrinsic" {
     pub fn discriminant_value<T>(v: &T) -> <T as DiscriminantKind>::Discriminant;
 
     /// Rust's "try catch" construct for unwinding. Invokes the function pointer `try_fn` with the
-    /// data pointer `data`, and calls `catch_fn` if a panic occurs while `try_fn` runs. It is
-    /// undefined behavior to catch an unwinding operation from another language with this
-    /// function.
+    /// data pointer `data`, and calls `catch_fn` if unwinding occurs while `try_fn` runs.
     ///
     /// `catch_fn` must not unwind.
     ///
-    /// The third argument is a function called if an unwind occurs (both Rust unwinds and foreign
-    /// unwinds). This function takes the data pointer and a pointer to the target-specific
-    /// exception object that was caught. For more information, see the compiler's source as well as
-    /// std's `catch_unwind` implementation.
+    /// The third argument is a function called if an unwind occurs (both Rust `panic` and foreign
+    /// unwinds). This function takes the data pointer and a pointer to the target- and
+    /// runtime-specific exception object that was caught.
     ///
-    /// The stable version of this intrinsic is `std::panic::catch_unwind`.
+    /// Note that in the case of a foreign unwinding operation, the exception object data may not be
+    /// safely usable from Rust, and should not be directly exposed via the standard library. To
+    /// prevent unsafe access, the library implementation may either abort the process or present an
+    /// opaque error type to the user.
+    ///
+    /// For more information, see the compiler's source, as well as the documentation for the stable
+    /// version of this intrinsic, `std::panic::catch_unwind`.
     #[rustc_nounwind]
     pub fn catch_unwind(try_fn: fn(*mut u8), data: *mut u8, catch_fn: fn(*mut u8, *mut u8)) -> i32;