Decouple `rustc_hir::print` into `rustc_hir_pretty`
High level summary:
- The HIR pretty printer, `rustc_hir::print` is moved into a new crate `rustc_hir_pretty`.
- `rustc_ast_pretty` and `rustc_errors` are dropped as `rustc_hir` dependencies.
- The dependence on HIR pretty is generally reduced, leaving `rustc_save_analysis`, `rustdoc`, `rustc_metadata`, and `rustc_driver` as the remaining clients.
The main goal here is to reduce `rustc_hir`'s dependencies and its size such that it can start and finish earlier, thereby working towards https://github.com/rust-lang/rust/issues/65031.
r? @Zoxc
Allow obtaining &mut OsStr
```rust
impl DerefMut for OsString {...} // type Target = OsStr
impl IndexMut<RangeFull> for OsString {...} // type Output = OsStr
```
---
This change is pulled out of #69937 per @dtolnay
This implements `DerefMut for OsString` to allow obtaining a `&mut OsStr`. This also implements `IndexMut for OsString`, which is used by `DerefMut`. This pattern is the same as is used by `Deref`.
This is necessary to for methods like `make_ascii_lowercase` which need to mutate the underlying value.
Fix cycle error when emitting suggestion for mismatched `fn` type
Fixes#66667
Previously, we called `tcx.typeck_tables_of` when determining whether or
not to emit a suggestion for a type error. However, we might already be
type-checking the `DefId` we pass to `typeck_tables_of` (it could be
anywhere in the query stack).
Fortunately, we only need the function signature, not the entire
`TypeckTables`. By using `tcx.fn_sig`, we avoid the possibility of cycle
errors while retaining the ability to emit a suggestion.
Remove framework in `dataflow/mod.rs` in favor of "generic" one
This is the culmination of the work described in rust-lang/compiler-team#202. All dataflow analyses (including the one in `clippy`) have been ported to use the framework in `dataflow/generic`, which can efficiently handle both gen/kill and generic problems. This PR moves the framework in `dataflow/generic` to `dataflow/framework`, and removes the gen/kill framework in `dataflow/mod.rs`.
More comprehensive documentation for the new framework is tracked in rust-lang/rustc-guide#564.
`clippy` will need to change the path it uses to import the dataflow analysis traits.
`error_bad_item_kind`: add help text
For example, this adds:
```
= help: consider moving the `use` import out to a nearby module scope
```
r? @petrochenkov @estebank
Fixes https://github.com/rust-lang/rust/issues/37205.
add 'fn write_u16s' to Memory
Added new function `Memory::write_u16s`. Needed in `MIRI` for implementing helper function to write wide_str to memory (for Windows).
- Added `Iterator::fold_first`, which is like `fold`, but uses the first element in the iterator as the initial accumulator
- Includes doc and doctest
- Rebase commit; see #65222 for details
Co-Authored-By: Tim Vermeulen <tvermeulen@me.com>
