The current structure makes it hard to tell that there are just four
distinct code paths, depending on how many items there are in `bb_items`
and `next_items`. This commit introduces a `match` that clarifies
things.

They should only appear in transcribers.

Also rename `inner_parse_loop` as `parse_tt_inner`, because it's no
longer just a loop.

For consistency, and to make the code slightly nicer.

…pe path

…fault

…, r=notriddle

Collapse blanket and auto-trait impls by default

Blocked on rust-lang#94740 (the two first commits come from it).

This behaviour was changed in rust-lang#88490 and apparently wasn't caught since then.

You can test it [here](https://rustdoc.crud.net/imperio/collapsed-by-default/test_docs/struct.Foo.html#blanket-implementations).

r? `@notriddle`

…trochenkov

`parse_tt` refactorings

Some readability improvements.

r? `@petrochenkov`

CTFE/Miri: detect out-of-bounds pointers in offset_from

Also I became uneasy with aggressively doing `try_to_int` here -- this will always succeed on Miri, leading to the wrong codepath being taken. We should rather try to convert them both to pointers, and use the integer path as a fallback, so that's what I implemented now.

Hiding whitespaces helps with the diff.

Fixes rust-lang/miri#1950

r? `@oli-obk`

…an-DPC

Make float parsing docs more comprehensive

I was working on some code with some specialized restrictions on float parsing. I noticed the doc comments for `f32::from_str` and `f64::from_str` were missing several cases of valid inputs that are otherwise difficult to discover without looking at source code.

I'm not sure if the doc comments were initially intended to contain a comprehensive description of valid inputs, but I figured it's useful to include these extra cases for reference.

…for-struct-field-type, r=cjgillot

Suggest using double colon when a struct field type include single colon

rust-lang#92685