improve documentation for `Fn*` traits
This PR is not yet a serious attempt at contribution. Rather, I'm opening this for discussion. I can think of a few things we may want to accomplish with the documentation of the `Fn`, `FnMut`, and `FnOnce` traits:
- the relationship between these traits and the closures that implement them
- examples of non-closure implementations
- the relationship between these traits and Rust's ownership semantics
show how iterating over `RangeTo` and `RangeToInclusive` fails
Feedback on PR #35701 seems to be positive, so this does the same thing for `RangeTo` and `RangeToInclusive`.
Doc: explain why Box/Rc/Arc methods do not take self
This can be confusing for newcomers, especially due to the argument name `this` that is used for Rc and Arc.
Batch up libsyntax breaking changes
Batch of the following syntax-[breaking-change] changes:
- #35591: Add a field `span: Span` to `ast::Generics`.
- #35618: Remove variant `Mod` of `ast::PathListItemKind` and refactor the remaining variant `ast::PathListKind::Ident` to a struct `ast::PathListKind_`.
- #35480: Change uses of `Constness` in the AST to `Spanned<Constness>`.
- c.f. `MethodSig`, `ItemKind`
- #35728: Refactor `cx.pat_enum()` into `cx.pat_tuple_struct()` and `cx.pat_path()`.
- #35850: Generalize the elements of lists in attributes from `MetaItem` to a new type `NestedMetaItem` that can represent a `MetaItem` or a literal.
- #35917: Remove traits `AttrMetaMethods`, `AttributeMethods`, and `AttrNestedMetaItemMethods`.
- Besides removing imports of these traits, this won't cause fallout.
- Add a variant `Union` to `ItemKind` to future proof for `union` (c.f. #36016).
- Remove inherent methods `attrs` and `fold_attrs` of `Annotatable`.
- Use methods `attrs` and `map_attrs` of `HasAttrs` instead.
r? @Manishearth
These fit with other From implementations between integer types.
This helps the coding style of avoiding the 'as' operator that sometimes
silently truncates, and signals that these specific conversions are
lossless and infaillible.
rustbuild: smarter `git submodule`-ing
With this commit, if one bootstraps rust against system llvm then the
src/llvm submodule is not updated/checked-out. This saves considerable
network bandwith when starting from a fresh clone of rust-lang/rust as
the llvm submodule is never cloned.
cc #30107
r? @alexcrichton
cc @petevine
~~We could also avoid updating the jemalloc submodule if --disable-jemalloc is used. It just hasn't been implemented.~~ Done
This probably doesn't handle "recursive" submodules correctly but I think we don't have any of those right now.
I'm still testing a bootstrap but already confirmed that the llvm submodule doesn't get updated when `--llvm-root` is passed to `configure`.
