diff options
| -rw-r--r-- | src/librustc_mir/diagnostics.rs | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/src/librustc_mir/diagnostics.rs b/src/librustc_mir/diagnostics.rs index 4df3004a9ad..f369324157a 100644 --- a/src/librustc_mir/diagnostics.rs +++ b/src/librustc_mir/diagnostics.rs @@ -1545,20 +1545,22 @@ Erroneous code example: ```compile_fail,E0505 struct Value {} +fn borrow(val: &Value) {} + fn eat(val: Value) {} fn main() { let x = Value{}; - { - let _ref_to_val: &Value = &x; - eat(x); - } + let _ref_to_val: &Value = &x; + eat(x); + borrow(_ref_to_val); } ``` -Here, the function `eat` takes the ownership of `x`. However, -`x` cannot be moved because it was borrowed to `_ref_to_val`. -To fix that you can do few different things: +Here, the function `eat` takes ownership of `x`. However, +`x` cannot be moved because the borrow to `_ref_to_val` +needs to last till the function `borrow`. +To fix that you can do a few different things: * Try to avoid moving the variable. * Release borrow before move. @@ -1569,14 +1571,15 @@ Examples: ``` struct Value {} +fn borrow(val: &Value) {} + fn eat(val: &Value) {} fn main() { let x = Value{}; - { - let _ref_to_val: &Value = &x; - eat(&x); // pass by reference, if it's possible - } + let _ref_to_val: &Value = &x; + eat(&x); // pass by reference, if it's possible + borrow(_ref_to_val); } ``` @@ -1585,12 +1588,15 @@ Or: ``` struct Value {} +fn borrow(val: &Value) {} + fn eat(val: Value) {} fn main() { let x = Value{}; { let _ref_to_val: &Value = &x; + borrow(_ref_to_val); } eat(x); // release borrow and then move it. } @@ -1602,14 +1608,15 @@ Or: #[derive(Clone, Copy)] // implement Copy trait struct Value {} +fn borrow(val: &Value) {} + fn eat(val: Value) {} fn main() { let x = Value{}; - { - let _ref_to_val: &Value = &x; - eat(x); // it will be copied here. - } + let _ref_to_val: &Value = &x; + eat(x); // it will be copied here. + borrow(_ref_to_val); } ``` |