[DOC] Improve `thread::panicking` documentaion.
Part of #29378
Takes care of: `panicking` could use some more advice on when to use this.
I mays have done a poor choice of introducing `Mutex`s.
r? @steveklabnik
Point at fields that make the type recursive
On recursive types of infinite size, point at all the fields that make
the type recursive.
```rust
struct Foo {
bar: Bar,
}
struct Bar {
foo: Foo,
}
```
outputs
```
error[E0072]: recursive type `Foo` has infinite size
--> file.rs:1:1
1 | struct Foo {
| ^^^^^^^^^^ recursive type has infinite size
2 | bar: Bar,
| -------- recursive here
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Foo` representable
error[E0072]: recursive type `Bar` has infinite size
--> file.rs:5:1
|
5 | struct Bar {
| ^^^^^^^^^^ recursive type has infinite size
6 | foo: Foo,
| -------- recursive here
|
= help: insert indirection (e.g., a `Box`, `Rc`, or `&`) at some point to make `Bar` representable
```
Allow # to appear in rustdoc code output.
"##" at the start of a trimmed rustdoc line is now cut to "#" and then
shown. If the user wanted to show "##", they can type "###".
I'm somewhat concerned about the potential implications for users, since this does make a potentially backwards-incompatible change. Previously, `##` had no special handling, and now we do change it. However, I'm not really sure what we can do here to improve this, and I can't think of any cases where `##` would likely be correct in a code block, though of course I could be wrong.
Fixes#41783.
Fix definitions of ULONG_PTR
The Windows type `ULONG_PTR` is supposed to be equivalent to `usize`, but several parts of the codebase currently define it as `u64`. Evidently this hasn't broken anything yet but it might cause annoying 32-bit-specific breakage in future.
See https://msdn.microsoft.com/en-gb/library/windows/desktop/aa383751(v=vs.85).aspx
r? @alexcrichton
Fix "an" usage
Since the pr i reviewed on got merged way before the author had a chance to quickly change it, i just did it myself. (Or well, someone else asked me to, if you want me to be honest)
Add an example to std:🧵:Result type
This PR is a part of https://github.com/rust-lang/rust/issues/29378. I submit this PR with the help (mentoring) of @steveklabnik. I'm still not sure my request is good enough but I don't want to spoil the issue with too much questions so I continue here. r? @steveklabnik
Move unicode Python script into libstd_unicode crate.
The only place this Python script is used is inside the libstd_unicode
crate, so lets move it there.
Refactor variance and remove last `[pub]` map
This PR refactors variance to work in a more red-green friendly way. Because red-green doesn't exist yet, it has to be a bit hacky. The basic idea is this:
- We compute a big map with the variance for all items in the crate; when you request variances for a particular item, we read it from the crate
- We now hard-code that traits are invariant (which they are, for deep reasons, not gonna' change)
- When building constraints, we compute the transitive closure of all things within the crate that depend on what using `TransitiveRelation`
- this lets us gin up the correct dependencies when requesting variance of a single item
Ah damn, just remembered, one TODO:
- [x] Update the variance README -- ah, I guess the README updates I did are sufficient
r? @michaelwoerister
Suggest `!` for bitwise negation when encountering a `~`
Fix#41679
Here is a program
```rust
fn main() {
let x = ~1;
}
```
It's output:
```
error: `~` can not be used as an unary operator
--> /home/fcc/temp/test.rs:4:13
|
4 | let x = ~1;
| ^^
|
= help: use `!` instead of `~` if you meant to bitwise negation
```
cc @bstrie
Reload nameserver information on lookup failure
As discussed in #41570, UNIX systems often cache the contents of `/etc/resolv.conf`, which can cause lookup failures to persist even after a network connection becomes available. This patch modifies lookup_host to force a reload of the nameserver entries following a lookup failure. This is in line with what many C programs already do (see #41570 for details). On systems with nscd, this should not be necessary, but not all systems run nscd.
Fixes#41570.
Depends on rust-lang/libc#585.
r? @alexcrichton
std: Avoid locks during TLS destruction on Windows
Gecko recently had a bug reported [1] with a deadlock in the Rust TLS
implementation for Windows. TLS destructors are implemented in a sort of ad-hoc
fashion on Windows as it doesn't natively support destructors for TLS keys. To
work around this the runtime manages a list of TLS destructors and registers a
hook to get run whenever a thread exits. When a thread exits it takes a look at
the list and runs all destructors.
Unfortunately it turns out that there's a lock which is held when our "at thread
exit" callback is run. The callback then attempts to acquire a lock protecting
the list of TLS destructors. Elsewhere in the codebase while we hold a lock over
the TLS destructors we try to acquire the same lock held first before our
special callback is run. And as a result, deadlock!
This commit sidesteps the issue with a few small refactorings:
* Removed support for destroying a TLS key on Windows. We don't actually ever
exercise this as a public-facing API, and it's only used during `lazy_init`
during racy situations. To handle that we just synchronize `lazy_init`
globally on Windows so we never have to call `destroy`.
* With no need to support removal the global synchronized `Vec` was tranformed
to a lock-free linked list. With the removal of locks this means that
iteration no long requires a lock and as such we won't run into the deadlock
problem mentioned above.
Note that it's still a general problem that you have to be extra super careful
in TLS destructors. For example no code which runs a TLS destructor on Windows
can call back into the Windows API to do a dynamic library lookup. Unfortunately
I don't know of a great way around that, but this at least fixes the immediate
problem that Gecko was seeing which is that with "well behaved" destructors the
system would still deadlock!
[1]: https://bugzilla.mozilla.org/show_bug.cgi?id=1358151
refactor NonZero, Shared, and Unique APIs
Major difference is that I removed Deref impls, as apparently LLVM has
trouble maintaining metadata with a `&ptr -> &ptr` API. This was cited
as a blocker for ever stabilizing this API. It wasn't that ergonomic
anyway.
* Added `get` to NonZero to replace Deref impl
* Added `ptr` getter to Shared/Unique to replace Deref impl
* Added Unique's `get` and `get_mut` conveniences to Shared
* Deprecated `as_mut_ptr` on Shared in favour of `ptr`
Note that Shared used to primarily expose only `*const` but there isn't
a good justification for that, so I made it `*mut`.
std: Prevent deadlocks in doctests on Windows
Windows historically has problems with threads panicking and the main thread
exiting at the same time, typically causing deadlocks. In the past (#25824)
we've joined on threads but this just prevents running the test for now to avoid
tampering with the example.
