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#### Note: this error code is no longer emitted by the compiler.
A lifetime cannot be determined in the given situation.
Erroneous code example:
```compile_fail
fn transmute_lifetime<'a, 'b, T>(t: &'a (T,)) -> &'b T {
match (&t,) { // error!
((u,),) => u,
}
}
let y = Box::new((42,));
let x = transmute_lifetime(&y);
```
In this code, you have two ways to solve this issue:
1. Enforce that `'a` lives at least as long as `'b`.
2. Use the same lifetime requirement for both input and output values.
So for the first solution, you can do it by replacing `'a` with `'a: 'b`:
```
fn transmute_lifetime<'a: 'b, 'b, T>(t: &'a (T,)) -> &'b T {
match (&t,) { // ok!
((u,),) => u,
}
}
```
In the second you can do it by simply removing `'b` so they both use `'a`:
```
fn transmute_lifetime<'a, T>(t: &'a (T,)) -> &'a T {
match (&t,) { // ok!
((u,),) => u,
}
}
```
|
