Autogenerate unstable compiler flag stubs for unstable-book

[kohsine]

Closes #141525.

Based on old PR #142135.

Parses rustc -Zhelp to generate doc stubs for unstable compiler flags if any are missing.

[rustbot]

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[clubby789]

For context, a previous attempt at this parsed the options macro: #154070 This was reverted in #154488. Would you be interested in investigating an approach that addresses the concerns raised?

If not, please add a Co-authored-by: credit with the original author of this code to your commit.

[kohsine]

For context, a previous attempt at this parsed the options macro: #154070 This was reverted in #154488. Would you be interested in investigating an approach that addresses the concerns raised?

I can address the concerns in #154488 here:

Moving the unstable options to a separate include! file is marginally more convenient for the unstable-book-gen tool, but a big hassle for compiler contributors looking to read or modify the list of unstable options. It breaks normal file layout conventions, interferes with navigation, and interferes with IDE features, all without ever being truly necessary.

Options file is not touched because it parses rustc -Zhelp instead.

The extra syn-based parser in unstable-book-gen is quite complicated, almost entirely undocumented, and seemingly buggy. That makes it extremely difficult to understand or modify, which in turn makes it effectively impossible to ever change the options! macro on the compiler side.

No external dependencies are used. It's all plain string matching and splitting. Should be fairly easy to modify for anyone looking to change the formatting of rustc -Zhelp.

The new tests in unstable-book-gen don't appear to be hooked up to run in CI.

There are no new tests.

The compiler changes don't appear to have been approved by a T-compiler reviewer.

Should probably link T-compiler since changing rustc -Zhelp output could break unstable-book build if this PR gets merged.

[kohsine]

Added Co-authored-by

[clubby789]

I can address the concerns here

I was asking if you'd like to investigate a macro-parsing approach which addresses these concerns. I think this is fine though;
@bors r+

[rust-bors]

📌 Commit d3201bd has been approved by clubby789

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 5. This pull request will be tested once the tree is reopened.

[JonathanBrouwer]

💔 I suspect this PR failed tests as part of a rollup
@bors r-

After fixing the problem, consider running a try job for the failed job before re-approving.

Link to failure: #157708 (comment)

[rust-bors]

This pull request was unapproved.

This PR was contained in a rollup (#157708), which was unapproved.

View changes since this unapproval

[clubby789]

no -Z options were found in x86_64-gnu-stable; probably that these options are unavailable in a stable build

[rustbot]

HIR ty lowering was modified

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Some changes occurred to constck

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compiletest directives have been modified. Please add or update docs for the
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Some changes occurred to diagnostic attributes.

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Some changes occurred in need_type_info.rs

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Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

changes to inspect_obligations.rs

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These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

Some changes occurred to the CTFE machinery

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clippy is developed in its own repository. If possible, consider making this change to rust-lang/rust-clippy instead.

cc @rust-lang/clippy

Some changes occurred in abstract_const.rs

cc @BoxyUwU

Warning

If you are changing how CI LLVM is built or linked, make sure to bump
src/bootstrap/download-ci-llvm-stamp.

cc @jieyouxu

Some changes occurred in src/tools/compiletest

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Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

changes to the core type system

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rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

Some changes occurred to the core trait solver

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rustc_codegen_gcc is developed in its own repository. If possible, consider making this change to rust-lang/rustc_codegen_gcc instead.

cc @antoyo, @GuillaumeGomez

Some changes occurred in compiler/rustc_hir/src/attrs

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This PR changes rustc_public

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Some changes occurred in const_evaluatable.rs

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Some changes occurred in match checking

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Some changes occurred to the CTFE / Miri interpreter

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[kohsine]

Should pass CI on stable now

@rustbot ready

[JonathanBrouwer]

Don't worry these rebase errors happen regularly 😂
@bors try jobs=x86_64-gnu-stable

[rust-bors]

☀️ Try build successful (CI)
Build commit: 7f60639 (7f60639b302eee795b0813365e6b17c615f9cad5, parent: 485ec3fbcc12fa14ef6596dabb125ad710499c9e)

[clubby789]

@bors r+

[rust-bors]

📌 Commit 4980543 has been approved by clubby789

It is now in the queue for this repository.