diff options
Diffstat (limited to 'src/libstd')
| -rw-r--r-- | src/libstd/io/mod.rs | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs index 917199f8ea8..7fba844897f 100644 --- a/src/libstd/io/mod.rs +++ b/src/libstd/io/mod.rs @@ -506,9 +506,18 @@ pub trait Read { /// /// No guarantees are provided about the contents of `buf` when this /// function is called, implementations cannot rely on any property of the - /// contents of `buf` being true. It is recommended that implementations + /// contents of `buf` being true. It is recommended that *implementations* /// only write data to `buf` instead of reading its contents. /// + /// Correspondingly, however, *users* of this trait may not assume any guarantees + /// about how the implementation uses `buf`. The trait is safe to implement, + /// so it is perfectly possible that the implementation might inspect that data. + /// As a caller, it is your responsibility to make sure that `buf` is initialized + /// before calling `read`. Calling `read` with an uninitialized `buf` (of the kind one + /// obtains via [`MaybeUninit<T>`]) is not safe, and can lead to undefined behavior. + /// + /// [`MaybeUninit<T>`]: ../mem/union.MaybeUninit.html + /// /// # Errors /// /// If this function encounters any form of I/O or other error, an error |