Closed
Description
I distilled this from an example in some actual code I have, although I'm not entirely sure that the distilled example reflects the problem in my original code. The program
struct A;
struct B<'a> {
a: &'a A,
b: &'a A,
}
impl <'a> B<'a> {
fn foo<'b>(&'b self) {
B {
a: self.a,
b: self.b,
};
}
}
fn main() { }fails to compile with this error:
test.rs:10:9: 13:10 error: cannot infer an appropriate lifetime for lifetime parameter `'a due to conflicting requirements
test.rs:10 B {
test.rs:11 a: self.a,
test.rs:12 b: self.b,
test.rs:13 };
test.rs:12:16: 12:22 note: first, the lifetime must be contained by the expression at 12:15...
test.rs:12 b: self.b,
^~~~~~
test.rs:12:16: 12:22 note: ...so that automatically reference is valid at the time of borrow
test.rs:12 b: self.b,
^~~~~~
test.rs:11:16: 11:22 note: but, the lifetime must also be contained by the expression at 11:15...
test.rs:11 a: self.a,
^~~~~~
test.rs:11:16: 11:22 note: ...so that automatically reference is valid at the time of borrow
test.rs:11 a: self.a,
^~~~~~
If I change the program slightly so that foo returns a B<'b> then everything works fine:
struct A;
struct B<'a> {
a: &'a A,
b: &'a A,
}
impl <'a> B<'a> {
fn foo<'b>(&'b self) -> B<'b> {
B {
a: self.a,
b: self.b,
}
}
}
fn main() { }