Pass `--test` flag through rustdoc to rustc so `#[test]` functions can be scraped
As a part of stabilizing the scrape examples extension in Cargo, I uncovered a bug where examples cannot be scraped from tests. See this test: https://github.com/rust-lang/cargo/pull/10343/files#diff-27aa4f012ebfebaaee61498d91d2370de460628405d136b05e77efe61e044679R2496
The issue is that when rustdoc is run on a test file, because `--test` is not passed as a rustc option, then functions annotated with `#[test]` are ignored by the compiler. So this PR changes rustdoc so when `--test` is passed in conjunction with a `--scrape-example-<suffix>` flag, then the `test` field of `rustc_interface::Config` is true.
r? `@camelid`
Include all contents of first line of scraped item in Rustdoc
This fixes#93528. When scraping examples, it extends the span of the enclosing item to include all characters up to the start of the first line of the span.
r? `@camelid`
`Decoder` has two impls:
- opaque: this impl is already partly infallible, i.e. in some places it
currently panics on failure (e.g. if the input is too short, or on a
bad `Result` discriminant), and in some places it returns an error
(e.g. on a bad `Option` discriminant). The number of places where
either happens is surprisingly small, just because the binary
representation has very little redundancy and a lot of input reading
can occur even on malformed data.
- json: this impl is fully fallible, but it's only used (a) for the
`.rlink` file production, and there's a `FIXME` comment suggesting it
should change to a binary format, and (b) in a few tests in
non-fundamental ways. Indeed #85993 is open to remove it entirely.
And the top-level places in the compiler that call into decoding just
abort on error anyway. So the fallibility is providing little value, and
getting rid of it leads to some non-trivial performance improvements.
Much of this commit is pretty boring and mechanical. Some notes about
a few interesting parts:
- The commit removes `Decoder::{Error,error}`.
- `InternIteratorElement::intern_with`: the impl for `T` now has the same
optimization for small counts that the impl for `Result<T, E>` has,
because it's now much hotter.
- Decodable impls for SmallVec, LinkedList, VecDeque now all use
`collect`, which is nice; the one for `Vec` uses unsafe code, because
that gave better perf on some benchmarks.
* Move call location logic from function constructor to rendering
* Fix issue with macro spans in scraping examples
* Clean up example loading logic
Documentation / newtype for DecorationInfo
Fix line number display
Serialize edition of call site, other small cleanup
Move rendering of examples into
Finalize design
Cleanup, rename found -> scraped
Softer yellow
Clean up dead code
Document scrape_examples
More simplification and documentation
Remove extra css
Test
