Rollup merge of #41249 - GuillaumeGomez:rustdoc-render, r=steveklabnik,frewsxcv

[rust.git] / src / librustc_mir / diagnostics.rs

diff --git a/src/librustc_mir/diagnostics.rs b/src/librustc_mir/diagnostics.rs
index eb16812af9b0225fa5714dcca15928b114e859a1..bb07081fe433b74dab3ccf6ae1fbce3480616218 100644 (file)
--- a/src/librustc_mir/diagnostics.rs
+++ b/src/librustc_mir/diagnostics.rs
@@ -244,6 +244,39 @@ const fn foo(mut x: u8) {
 ```
 "##,
 
+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. Example:
+
+```
+#![feature(box_syntax)]
+
+fn main() {
+    let array: &[isize] = &[1, 2, 3];
+    let _x: Box<&[isize]> = box array; // ok!
+}
+```
+"##,
+
 E0396: r##"
 The value behind a raw pointer can't be determined at compile-time
 (or even link-time), which means it can't be used in a constant