rustdoc: Replace unstable flag `--doctest-compilation-args` with a simpler one: `--doctest-build-arg`
Tracking issue: https://github.com/rust-lang/rust/issues/134172.
Context: https://github.com/rust-lang/rust/pull/137096#issuecomment-2776318800
Yeets the ad hoc shell-like lexer for 'nested' program arguments.
No FCP necessary since the flag is unstable.
I've chosen to replace `compilation` with `build` because it's shorter (you now need to pass it multiple times in order to pass many arguments to the doctest compiler, so it matters a bit) and since I prefer it esthetically.
**Issue**: Even though we don't process the argument passed to `--doctest-build-arg`, we end up passing it via an argument file (`rustc `@argfile`)` which delimits arguments by line break (LF or CRLF, [via](https://doc.rust-lang.org/rustc/command-line-arguments.html#path-load-command-line-flags-from-a-path)) meaning ultimately the arguments still get split which is unfortunate. Still, I think this change is an improvement over the status quo.
I'll update the tracking issue if/once this PR merges. I'll also add the (CR)LF issue to 'unresolved question'.
r? GuillaumeGomez
r? notriddle
Fix detection of main function if there are expressions around it
Fixes#140162.
Fixes#139651.
Once this is merged, we can backport and I'll send a follow-up to emit a warning in case a `main` function is about to be "wrapped" (and therefore not run).
r? `@fmease`
try-job: x86_64-mingw-1
Fix 2024 edition doctest panic output
Fixes#137970.
The problem was that the output was actually displayed by rustc itself because we're exiting with `Result<(), String>`, and the display is really not great. So instead, we get the output, we print it and then we return an `ExitCode`.
r? ````@aDotInTheVoid````
Greatly simplify doctest parsing and information extraction
The original process was pretty terrible, as it tried to extract information such as attributes by performing matches over tokens like `#!`, which doesn't work very well considering you can have `# ! [`, which is valid.
Also, it now does it in one pass: if the parser is happy, then we try to extract information, otherwise we return early.
r? `@fmease`
This prevents the included test case from getting at nightly-only
features when run on stable. The harness builds with
RUSTC_BOOTSTRAP, but the bundle doesn't.
rustdoc: make doctest span tweak a 2024 edition change
Fixes#132203
This is a compatibility hack, because I think the new behavior is better. When an A `include_str!` B, and B `include_str!` C, the path to C should be resolved relative to B, not A. That's how `include!` itself works, so that's how `include_str!` with should work.
rustdoc: Remove usage of `allow(unused)` attribute on `no_run` merged doctests
Fixes [#130681](https://github.com/rust-lang/rust/issues/130681).
It fixes the behaviour difference with the current doctests.
r? ``@notriddle``
Fixes#132203
This is a compatibility hack, because I think the new behavior is better.
When an A `include_str!` B, and B `include_str!` C, the path to C should
be resolved relative to B, not A. That's how `include!` itself works,
so that's how `include_str!` with should work.
