diff options
Diffstat (limited to 'src/tools/clippy/src/docs/await_holding_refcell_ref.txt')
-rw-r--r-- | src/tools/clippy/src/docs/await_holding_refcell_ref.txt | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/src/tools/clippy/src/docs/await_holding_refcell_ref.txt b/src/tools/clippy/src/docs/await_holding_refcell_ref.txt new file mode 100644 index 000000000..226a261b9 --- /dev/null +++ b/src/tools/clippy/src/docs/await_holding_refcell_ref.txt @@ -0,0 +1,47 @@ +### What it does +Checks for calls to await while holding a `RefCell` `Ref` or `RefMut`. + +### Why is this bad? +`RefCell` refs only check for exclusive mutable access +at runtime. Holding onto a `RefCell` ref across an `await` suspension point +risks panics from a mutable ref shared while other refs are outstanding. + +### Known problems +Will report false positive for explicitly dropped refs +([#6353](https://github.com/rust-lang/rust-clippy/issues/6353)). A workaround for this is +to wrap the `.borrow[_mut]()` call in a block instead of explicitly dropping the ref. + +### Example +``` +async fn foo(x: &RefCell<u32>) { + let mut y = x.borrow_mut(); + *y += 1; + baz().await; +} + +async fn bar(x: &RefCell<u32>) { + let mut y = x.borrow_mut(); + *y += 1; + drop(y); // explicit drop + baz().await; +} +``` + +Use instead: +``` +async fn foo(x: &RefCell<u32>) { + { + let mut y = x.borrow_mut(); + *y += 1; + } + baz().await; +} + +async fn bar(x: &RefCell<u32>) { + { + let mut y = x.borrow_mut(); + *y += 1; + } // y dropped here at end of scope + baz().await; +} +```
\ No newline at end of file |