The cfg isn't actually necessary, since `--emit=metadata` does not
actually do enough validation for it to fail on any platform. However,
I feel a little more comfortable leaving it in.

Unhide the feature flag, since I think that is important to display.

And tuple variant syntax, but that didn't fit in the subject :)

Now the fact that these are suggestions is exposed both to the layout
engine and to IDEs and rustfix for automatic application.

- Add documentation about task lists

We escape certain LLVM-specific features when passing the inline
assembly string to the LLVM. Until now, however, there was no test
making sure this behaviour stays intact. This commit adds such a test!

tidy: Run tidy style against markdown files.

This adds tidy checks for markdown files.  I think it is useful to have some style enforcement (for the same reasons the style is enforced on other files).  I think it is worthwhile to avoid `ignore` on rust examples since having broken code in documentation is frustrating.  Avoiding trailing whitespace is good because it has semantic meaning in markdown, which I think should be avoided.

…lnay

BTree: fix documentation of unstable public members

As rightfully requested in #62924 & #70530.
r? `@Mark-Simulacrum`

Refactor `PrimitiveTypeTable` for Clippy

I removed `PrimitiveTypeTable` and added `PrimTy::ALL` and `PrimTy::from_name` in its place. This allows Clippy to use `PrimTy::from_name` for the `builtin_type_shadow` lint, and a `const` list of primitive types is deleted from Clippy code (the goal). All changes should be a little faster, if anything.

typeck: Emit structured suggestions for tuple struct syntax

And tuple variant syntax, but that didn't fit in the subject :)

Now the fact that these are suggestions is exposed both to the layout
engine and to IDEs and rustfix for automatic application.

Miscellaneous small diagnostics cleanup

Enable 'task list' markdown extension

Closes #71183.

…nieu

Add a test for escaping LLVMisms in inline asm

We escape certain LLVM-specific features when passing the inline
assembly string to the LLVM. Until now, however, there was no test
making sure this behaviour stays intact. This commit adds such a test!

r? `@Amanieu`
cc `@joshtriplett`