1 files changed, 38 insertions, 0 deletions
diff --git a/src/librustc_trans/diagnostics.rs b/src/librustc_trans/diagnostics.rs
index f7f065a3562..d36878b0332 100644
--- a/src/librustc_trans/diagnostics.rs
+++ b/src/librustc_trans/diagnostics.rs
@@ -12,6 +12,44 @@
 
 register_long_diagnostics! {
 
+E0510: r##"
+`return_address` was used in an invalid context. Erroneous code example:
+
+```ignore
+#![feature(intrinsics)]
+
+extern "rust-intrinsic" {
+    fn return_address() -> *const u8;
+}
+
+unsafe fn by_value() -> i32 {
+    let _ = return_address();
+    // error: invalid use of `return_address` intrinsic: function does
+    //        not use out pointer
+    0
+}
+```
+
+Return values may be stored in a return register(s) or written into a so-called
+out pointer. In case the returned value is too big (this is
+target-ABI-dependent and generally not portable or future proof) to fit into
+the return register(s), the compiler will return the value by writing it into
+space allocated in the caller's stack frame. Example:
+
+```
+#![feature(intrinsics)]
+
+extern "rust-intrinsic" {
+    fn return_address() -> *const u8;
+}
+
+unsafe fn by_pointer() -> String {
+    let _ = return_address();
+    String::new() // ok!
+}
+```
+"##,
+
 E0511: r##"
 Invalid monomorphization of an intrinsic function was used. Erroneous code
 example: