As discovered in #29298, `env::set_var("", "")` will panic, but it turns out
that it *also* deadlocks on Unix systems. This happens because if a panic
happens while holding the environment lock, we then go try to read
RUST_BACKTRACE, grabbing the environment lock, causing a deadlock.
Specifically, the changes made here are:
* The environment lock is pushed into `std::sys` instead of `std::env`. This
also only puts it in the Unix implementation, not Windows where the functions
are already threadsafe.
* The `std::sys` implementation now returns `io::Result` so panics are
explicitly at the `std::env` level. The panic messages have also been improved
in these situations.
It's possible that there is some meaning I'm not grasping from the headers "Traits bounds for generic functions" and "Traits bounds for generic structs", but they seem to me like they could be clearer and more grammatically correct.
Qualified paths allow full path after the `>::`. For example
```rust
<T as Foo>::U::generic_method::<f64>()
```
The example is taken from `test/run-pass/associated-item-long-paths.rs`.
{BTree,Hash}{Map,Set} will not update their key if it already exists, which
can matter with more complex keys. This behavior is now documented.
Fixes#26888
{BTree,Hash}{Map,Set} will not update their key if it already exists, which
can matter with more complex keys. This behavior is now documented.
Fixes#26888
Qualified paths allow full path after the `>::`. For example
```rust
<T as Foo>::U::generic_method::<f64>()
```
The example is taken from `test/run-pass/associated-item-long-paths.rs`.
When reading this paragraph, the beginning Rust programmer is starting
to write a Hello World program. We have just told her to name the file
`main.rs`, and immediately afterward, a `hello_world.rs` is mentioned.
I changed this to an unrelated filename (incidentally one that appears
in this repository) to make it clear that this is just an example.
Also, wording it as a declarative sentence rather than an imperative one
further separates it from the Hello World instructions in this section.
r? @steveklabnik
(Let me know if I'm sending too many PRs -- I can batch up TRPL edits, say, per chapter, if that works better. Or I can just refrain from editing TRPL as I read through it, if these are not sufficiently useful.)
The paragraph here seemed confusing, so I reworded it. Also added
another possible reason why `curl | sh` might be objectionable to users.
r? @steveklabnik
This is a pretty trivial change. My eye caught some inconsistent whitespace while perusing compiler errors tonight. Specifically, I changed `//correct` to `// correct`, and got rid of some trailing whitespace that isn't seen in other code snippets.
This commit expands the "supported platforms" section of the book to include
documentation on the tiers that Rust currently has as well as organizing all
supported platforms into these various tiers. Infrastructure improvements over
the next few months are likely to change the location of may of these platforms
over, but for now this should faithfully represent what we've got today!
When reading this paragraph, the beginning Rust programmer is starting
to write a Hello World program. We have just told her to name the file
`main.rs`, and immediately afterward, a `hello_world.rs` is mentioned.
I changed this to an unrelated filename (incidentally one that appears
in this repository) to make it clear that this is just an example.
Also, wording it as a declarative sentence rather than an imperative one
further separates it from the Hello World instructions in this section.
This commit expands the "supported platforms" section of the book to include
documentation on the tiers that Rust currently has as well as organizing all
supported platforms into these various tiers. Infrastructure improvements over
the next few months are likely to change the location of may of these platforms
over, but for now this should faithfully represent what we've got today!
Yay, markdown isn't standardized and rustbook's parser has subtle incompatibilities with Github's! So in the Github preview you don't see that this list fails to separate from the previous paragraph. I think this should fix it, but I didn't check.
