bjoernager/rust
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Add a warning to File about mutability.

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Fixes #47708.
This commit is contained in:
Alexis Hunt 2018-02-16 08:51:40 -05:00
parent 5570cdcc9e
commit e9c75a889f
1 changed files with 15 additions and 0 deletions
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15
src/libstd/fs.rs
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@ -81,9 +81,18 @@ use time::SystemTime;
/// # }
/// ```
///
/// Note that, although read and write methods require a `&mut File`, because
/// of the interfaces for [`Read`] and [`Write`], it is still possible to
/// modify a file through a `&File`, either through methods that take `&File`
/// or by retrieving a raw OS filehandle and modifying the file that way.
/// Additionally, many operating systems allow concurrent modification of files
/// by different processes. Care should be taken not to assume that holding a
/// `&File` means that the file will not change.
///
/// [`Seek`]: ../io/trait.Seek.html
/// [`String`]: ../string/struct.String.html
/// [`Read`]: ../io/trait.Read.html
/// [`Write`]: ../io/trait.Write.html
/// [`BufReader<R>`]: ../io/struct.BufReader.html
#[stable(feature = "rust1", since = "1.0.0")]
pub struct File {
@ -459,6 +468,9 @@ impl File {
/// # Ok(())
/// # }
/// ```
///
/// Note that this method alters the content of the underlying file, even
/// though it takes `&self` rather than `&mut self`.
#[stable(feature = "rust1", since = "1.0.0")]
pub fn set_len(&self, size: u64) -> io::Result<()> {
self.inner.truncate(size)
@ -557,6 +569,9 @@ impl File {
/// # Ok(())
/// # }
/// ```
///
/// Note that this method alters the permissions of the underlying file,
/// even though it takes `&self` rather than `&mut self`.
#[stable(feature = "set_permissions_atomic", since = "1.16.0")]
pub fn set_permissions(&self, perm: Permissions) -> io::Result<()> {
self.inner.set_permissions(perm.0)