Parsing the code block's LangString (```foo) previously checked itself
to see if we were on nightly; that isn't the right place to do so. Move
that check slightly outwards to better abstract LangString.
(This is also an optimization as we avoid the costly environment
variable load of RUSTC_BOOTSTRAP).
Don't format!() string literals
Prefer `to_string()` to `format!()` take 2, this time targetting string literals. In some cases (`&format!("...")` -> `"..."`) also removes allocations. Occurences of `format!("")` are changed to `String::new()`.
RFC 2008 non-exhaustive enums/structs: Rustdoc
Part of #44109. Not sure how those who maintain rustdoc primarily would prefer this addition look or where it should be placed, happy to make any changes required.
r? @QuietMisdreavus (not sure if this is the right person, just guessing)
Rollup of 14 pull requests
Successful merges:
- #51619 (rust: add initial changes to support powerpc64le musl)
- #51793 (Fix variant background color on hover in search results)
- #52005 (Update LLVM to bring in a wasm codegen fix)
- #52016 (Deduplicate error reports for statics)
- #52019 ([cross-lang-lto] Allow the linker to choose the LTO-plugin (which is useful when using LLD))
- #52030 (Any docs preposition change)
- #52031 (Strenghten synchronization in `Arc::is_unique`)
- #52033 ([Gardening] Update outdated comments: ByVal -> Scalar)
- #52055 (Include VS 2017 in error message.)
- #52063 (Add a link to the rustc docs)
- #52073 (Add a punch card to weird expressions test)
- #52080 (Improve dependency deduplication diagnostics)
- #52093 (rustc: Update tracking issue for wasm_import_module)
- #52096 (Fix typo in cell.rs)
Failed merges:
rustdoc codeblock hash escape
So that docstring text such as the following (in a code block) can be created ergonomically:
```rust
let s = "
foo
# bar
baz
";
```
Such code in a docstring hide the <code> # bar</code> line.
Previously, using two consecutive hashes <code> ## bar</code> would turn the line into _shown_ `# bar`, losing the leading whitespace. A line of code like <code> # bar</code> (such as in the example above) **could not be represented** in the docstring text.
This commit makes the two consecutive hashes not also trim the leading whitespace — the two hashes simply **escape** into a single hash and do not hide the line, leaving the rest of that line unaffected. The new docstring text to achieve the above code block is:
```rust
/// ```
/// let s = "
/// foo
/// ## bar
/// baz
/// ";
/// ```
```
async/await
This PR implements `async`/`await` syntax for `async fn` in Rust 2015 and `async` closures and `async` blocks in Rust 2018 (tracking issue: https://github.com/rust-lang/rust/issues/50547). Limitations: non-`move` async closures with arguments are currently not supported, nor are `async fn` with multiple different input lifetimes. These limitations are not fundamental and will be removed in the future, however I'd like to go ahead and get this PR merged so we can start experimenting with this in combination with futures 0.3.
Based on https://github.com/rust-lang/rust/pull/51414.
cc @petrochenkov for parsing changes.
r? @eddyb
