macros: clean up scopes of expanded `#[macro_use]` imports
This PR changes the scope of macro-expanded `#[macro_use]` imports to match that of unexpanded `#[macro_use]` imports. For example, this would be allowed:
```rust
example!();
macro_rules! m { () => { #[macro_use(example)] extern crate example_crate; } }
m!();
```
This PR also enforces the full shadowing restrictions from RFC 1560 on `#[macro_use]` imports (currently, we only enforce the weakened restrictions from #36767).
This is a [breaking-change], but I believe it is highly unlikely to cause breakage in practice.
r? @nrc
Error monitor should emit error to stderr instead of stdout
We are pretty consistent about emitting to stderr, except for when there is actually an error, in which case we emit to stdout. This seems a bit backwards. This PR just changes that exception to emit to stderr. This is useful for the RLS since the LS protocol uses stdout (grrr).
r? @alexcrichton
Avoid allocations in `Decoder::read_str`.
`opaque::Decoder::read_str` is very hot within `rustc` due to its use in
the reading of crate metadata, and it currently returns a `String`. This
commit changes it to instead return a `Cow<str>`, which avoids a heap
allocation.
This change reduces the number of calls to `malloc` by almost 10% in
some benchmarks.
This is a [breaking-change] to libserialize.
Add comparison operators to boolean const eval.
I think it might be worth adding tests here, but since I don't know how or where to do that, I have not done so yet. Willing to do so if asked and given an explanation as to how.
Fixes#37047.
Fixing now incorrect Hash impl for TransItem.
Using as_ptr() rather than a pointer cast for string formatting.
Fixing Borrow and Lift impls for Substs.
Move usages of tcx.mk_substs to Substs::new iterator-based version.
Changed 0 into '0'
Right now `0` is an undefined production rule.
[Documentation following the grammar specification](https://doc.rust-lang.org/nightly/std/fmt/#sign0) strongly suggests `'0'` is meant as it is used as a character literal.
r? @steveklabnik
ICH: Enable some cases in trait definition hashing.
Enable some test cases originally written by @eulerdisk. The tests can be enabled now because @MathieuBordere has fixed the underlying problem in #36974.
r? @nikomatsakis
Merge `Printer::token` and `Printer::size`.
Logically, it's a vector of pairs, so might as well represent it that
way.
The commit also changes `scan_stack` so that it is initialized with the
default size, instead of the excessive `55 * linewidth` size, which it
usually doesn't get even close to reaching.
Book: Be very explicit of lifetimes being descriptive
... not prescriptive. Pointed out in https://users.rust-lang.org/t/what-if-i-get-lifetimes-wrong/7535/4, which was a revelation to me and made me think this should be more clear in the book. I'm not sure if I got this entirely right or if the wording is good, but I figured a PR is more helpful than a simple issue.
r? @steveklabnik
Small Note: There's also https://github.com/rust-lang/book, should I have sent the PR there? It doesn't coincide with the online book though, so I figured it's better of here.
Add method str::repeat(self, usize) -> String
It is relatively simple to repeat a string n times:
`(0..n).map(|_| s).collect::<String>()`. It becomes slightly more
complicated to do it “right” (sizing the allocation up front), which
warrants a method that does it for us.
This method is useful in writing testcases, or when generating text.
`format!()` can be used to repeat single characters, but not repeating
strings like this.
