From 31b9060ede89c7c11d7d829c3d4b50649bb7f07e Mon Sep 17 00:00:00 2001
From: Guillaume Gomez <guillaume1.gomez@gmail.com>
Date: Fri, 27 May 2016 22:05:10 +0200
Subject: [PATCH] Improve E0161 error explanation

---
 src/librustc/diagnostics.rs        |  3 +--
 src/librustc_passes/diagnostics.rs | 27 ++++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/src/librustc/diagnostics.rs b/src/librustc/diagnostics.rs
index a410a5949bdc8..d838de4a33122 100644
--- a/src/librustc/diagnostics.rs
+++ b/src/librustc/diagnostics.rs
@@ -438,12 +438,11 @@ This error indicates that the compiler found multiple functions with the
 `#[start]` attribute. This is an error because there must be a unique entry
 point into a Rust program. Example:
 
-
 ```
 #![feature(start)]
 
 #[start]
-fn foo(argc: isize, argv: *const *const u8) -> isize {} // ok!
+fn foo(argc: isize, argv: *const *const u8) -> isize { 0 } // ok!
 ```
 "##,
 
diff --git a/src/librustc_passes/diagnostics.rs b/src/librustc_passes/diagnostics.rs
index 77f896e011b93..cba8bd73c014e 100644
--- a/src/librustc_passes/diagnostics.rs
+++ b/src/librustc_passes/diagnostics.rs
@@ -50,11 +50,36 @@ match 5u32 {
 "##,
 
 E0161: r##"
+A value was moved. However, its size was not known at compile time, and only
+values of a known size can be moved.
+
+Erroneous code example:
+
+```compile_fail
+#![feature(box_syntax)]
+
+fn main() {
+    let array: &[isize] = &[1, 2, 3];
+    let _x: Box<[isize]> = box *array;
+    // error: cannot move a value of type [isize]: the size of [isize] cannot
+    //        be statically determined
+}
+```
+
 In Rust, you can only move a value when its size is known at compile time.
 
 To work around this restriction, consider "hiding" the value behind a reference:
 either `&x` or `&mut x`. Since a reference has a fixed size, this lets you move
-it around as usual.
+it around as usual. Example:
+
+```
+#![feature(box_syntax)]
+
+fn main() {
+    let array: &[isize] = &[1, 2, 3];
+    let _x: Box<&[isize]> = box array; // ok!
+}
+```
 "##,
 
 E0265: r##"