diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/panicking.rs | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/src/libstd/panicking.rs b/src/libstd/panicking.rs index 0be71b52d9e..7bc86650a73 100644 --- a/src/libstd/panicking.rs +++ b/src/libstd/panicking.rs @@ -251,21 +251,20 @@ pub unsafe fn r#try<R, F: FnOnce() -> R>(f: F) -> Result<R, Box<dyn Any + Send>> // // We go through a transition where: // - // * First, we set the data to be the closure that we're going to call. + // * First, we set the data field `f` to be the argumentless closure that we're going to call. // * When we make the function call, the `do_call` function below, we take - // ownership of the function pointer. At this point the `Data` union is + // ownership of the function pointer. At this point the `data` union is // entirely uninitialized. // * If the closure successfully returns, we write the return value into the - // data's return slot. Note that `ptr::write` is used as it's overwriting - // uninitialized data. + // data's return slot (field `r`). + // * If the closure panics (`do_catch` below), we write the panic payload into field `p`. // * Finally, when we come back out of the `try` intrinsic we're // in one of two states: // // 1. The closure didn't panic, in which case the return value was - // filled in. We move it out of `data` and return it. - // 2. The closure panicked, in which case the return value wasn't - // filled in. In this case the entire `data` union is invalid, so - // there is no need to drop anything. + // filled in. We move it out of `data.r` and return it. + // 2. The closure panicked, in which case the panic payload was + // filled in. We move it out of `data.p` and return it. // // Once we stack all that together we should have the "most efficient' // method of calling a catch panic whilst juggling ownership. |