Check for duplicate loop labels in function bodies.
See also: http://internals.rust-lang.org/t/psa-rejecting-duplicate-loop-labels/1833
The change, which we are putting in as future-proofing in preparation for future potential additions to the language (namely labeling arbitrary blocks and using those labels in borrow expressions), means that code like this will start emitting warnings:
```rust
fn main() {
{ 'a: loop { break; } }
{ 'a: loop { break; } }
}
```
To make the above code compile without warnings, write this instead:
```rust
fn main() {
{ 'a: loop { break; } }
{ 'b: loop { break; } }
}
```
Since this change is only introducing a new warnings, this change is non-breaking.
Fix#21633
Note: this Warns rather than error on shadowing problems involving labels.
We took this more conservative option mostly due to issues with
hygiene being broken for labels and/or lifetimes.
Add FIXME regarding non-hygienic comparison.
This patch adds a `Debug` impl for `std::fs::File`.
On all platforms (Unix and Windows) it shows the file descriptor.
On Linux, it displays the path and access mode as well.
Ideally we should show the path/mode for all platforms, not just Linux,
but this will do for now.
cc #24570
This patch adds a `Debug` impl for `std::fs::File`.
On all platforms (Unix and Windows) it shows the file descriptor.
On Linux, it displays the path and access mode as well.
Ideally we should show the path/mode for all platforms, not just Linux,
but this will do for now.
cc #24570
Many unsafe features are now in the unstable section, so this section is
really just about raw pointers now. That also makes sense for its place
in the TOC.
This addresses part of #12905.
Without the `box` keyword, one of these two reasons is not correct, so
let's just eliminate this section and elaborate on the reason for the
legit use case inline.
Fixes#24511
Fixes#24173
These docs could all use examples, so for now, let's just remove the bad one, and when I go over this whole module I'll put in better ones.
When `liballoc` is compiled with `--cfg feature=\"external_features\"`, several `improper_ctypes` warnings are generated. Since these warnings are harmless, I have added a directive to suppress them.
Many unsafe features are now in the unstable section, so this section is
really just about raw pointers now. That also makes sense for its place
in the TOC.
This addresses part of #12905.
Without the `box` keyword, one of these two reasons is not correct, so
let's just eliminate this section and elaborate on the reason for the
legit use case inline.
Fixes#24511
