diff options
Diffstat (limited to 'tests/ui/async-await/multiple-lifetimes/ret-ref.rs')
-rw-r--r-- | tests/ui/async-await/multiple-lifetimes/ret-ref.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/tests/ui/async-await/multiple-lifetimes/ret-ref.rs b/tests/ui/async-await/multiple-lifetimes/ret-ref.rs new file mode 100644 index 000000000..149c020f9 --- /dev/null +++ b/tests/ui/async-await/multiple-lifetimes/ret-ref.rs @@ -0,0 +1,44 @@ +// edition:2018 + +// Test that we get the expected borrow check errors when an async +// function (which takes multiple lifetimes) only returns data from +// one of them. + +async fn multiple_named_lifetimes<'a, 'b>(a: &'a u8, _: &'b u8) -> &'a u8 { + a +} + +// Both are borrowed whilst the future is live. +async fn future_live() { + let mut a = 22; + let mut b = 44; + let future = multiple_named_lifetimes(&a, &b); + a += 1; //~ ERROR cannot assign + b += 1; //~ ERROR cannot assign + let p = future.await; + drop(p); +} + +// Just the return value is live after future is awaited. +async fn just_return_live() { + let mut a = 22; + let mut b = 44; + let future = multiple_named_lifetimes(&a, &b); + let p = future.await; + a += 1; //~ ERROR cannot assign + b += 1; + drop(p); +} + +// Once `p` is dead, both `a` and `b` are unborrowed. +async fn after_both_dead() { + let mut a = 22; + let mut b = 44; + let future = multiple_named_lifetimes(&a, &b); + let p = future.await; + drop(p); + a += 1; + b += 1; +} + +fn main() { } |