This reverts commit 64acb7d.

This reverts commit d59b1f1.

This reverts commit 5b4bc05.

This reverts commit 8a1dd69.

This reverts commit 059b68d.

Note that this was manually adjusted to retain some of the refactoring
introduced by commit 059b68d, so that it could
likewise retain the correction introduced in commit
5b4bc05

Fixes rust-lang#88803

…the impl block

Currently, for the following code, the compiler produces the errors like the
following error:
```rust
struct Type<T>

impl<T: Clone> Type<T> {
	fn const f() {}
}
```
```text
error[E0658]: trait bounds other than `Sized` on const fn parameters are unstable
 --> ./test.rs:3:6
  |
3 | impl<T: Clone> Type<T> {
  |      ^
  |
  = note: see issue rust-lang#57563 <rust-lang#57563> for more information
  = help: add `#![feature(const_fn_trait_bound)]` to the crate attributes to enable
```

This can be confusing (especially to newcomers) since the error mentions
"const fn parameters", but highlights only the impl.

This commits adds function highlighting, changing the error to the following:

```text
error[E0658]: trait bounds other than `Sized` on const fn parameters are unstable
 --> ./test.rs:3:6
  |
3 | impl<T: Clone> Type<T> {
  |      ^
4 |     pub const fn f() {}
  |     ---------------- function declared as const here
  |
  = note: see issue rust-lang#57563 <rust-lang#57563> for more information
  = help: add `#![feature(const_fn_trait_bound)]` to the crate attributes to enable
```

Since 88839 `min_align_of` is lowered to AlignOf operator.

…haelwoerister

Introduce -Z remap-cwd-prefix switch

This switch remaps any absolute paths rooted under the current
working directory to a new value. This includes remapping the
debug info in `DW_AT_comp_dir` and `DW_AT_decl_file`.

Importantly, this flag does not require passing the current working
directory to the compiler, such that the command line can be
run on any machine (with the same input files) and produce the
same results. This is critical property for debugging compiler
issues that crop up on remote machines.

This is based on adetaylor's rust-lang@dbc4ae7

Major Change Proposal: rust-lang/compiler-team#450
Discussed on rust-lang#38322. Would resolve issue rust-lang#87325.

…ports, r=Amanieu

Remove `cfg(doc)` from std::os module reexports to fix rustdoc linking issues

Fixes rust-lang#88304.

I tested it based on rust-lang#88292.

Not sure if it's the best approach, but at least it makes thing a bit simpler.

cc ````@jyn514````

…xpr-parse, r=nagisa

Accept `m!{ .. }.method()` and `m!{ .. }?` statements.

This PR fixes something that I keep running into when using `quote!{}.into()` in a proc macro to convert the `proc_macro2::TokenStream` to a `proc_macro::TokenStream`:

Before:

```
error: expected expression, found `.`
 --> src/lib.rs:6:6
  |
4 |     quote! {
5 |         ...
6 |     }.into()
  |      ^ expected expression
```

After:
```
```
(No output, compiles fine.)

---

Context:

For expressions like `{ 1 }` and `if true { 1 } else { 2 }`, we accept them as full statements without a trailing `;`, which means the following is not accepted:

```rust
{ 1 } - 1 // error
```

since that is parsed as two statements: `{ 1 }` and `-1`. Syntactically correct, but the type of `{ 1 }` should be `()` as there is no `;`.

However, for specifically `.` and `?` after the `}`, we do [continue parsing it as an expression](https://github.com/rust-lang/rust/blob/13db8440bbbe42870bc828d4ec3e965b38670277/compiler/rustc_parse/src/parser/expr.rs#L864-L876):

```rust
{ "abc" }.len(); // ok
```

For braced macro invocations, we do not do this:

```rust
vec![1, 2, 3].len(); // ok
vec!{1, 2, 3}.len(); // error
```

(It parses `vec!{1, 2, 3}` as a full statement, and then complains about `.len()` not being a valid expression.)

This PR changes this to also look for a `.` and `?` after a braced macro invocation. We can be sure the macro is an expression and not a full statement in those cases, since no statement can start with a `.` or `?`.

… r=davidtwco

Revert anon union parsing

Revert PR rust-lang#84571 and rust-lang#85515, which implemented anonymous union parsing in a manner that broke the context-sensitivity for the `union` keyword and thus broke stable Rust code.

Fix rust-lang#88583.

…r=estebank

feat(rustc_typeck): suggest removing bad parens in `(recv.method)()`

Fixes rust-lang#88803

…_a_bound_in_impl_block_error, r=estebank

Highlight the `const fn` if error happened because of a bound on the impl block

Currently, for the following code, the compiler produces the errors like the
following:
```rust
struct Type<T>(T);

impl<T: Clone> Type<T> {
    const fn f() {}
}
```
```text
error[E0658]: trait bounds other than `Sized` on const fn parameters are unstable
 --> ./test.rs:3:6
  |
3 | impl<T: Clone> Type<T> {
  |      ^
  |
  = note: see issue rust-lang#57563 <rust-lang#57563> for more information
  = help: add `#![feature(const_fn_trait_bound)]` to the crate attributes to enable
```

This can be confusing (especially to newcomers) since the error mentions "const fn parameters", but highlights only the impl.

This PR adds function highlighting, changing the error to the following:

```text
error[E0658]: trait bounds other than `Sized` on const fn parameters are unstable
 --> ./test.rs:3:6
  |
3 | impl<T: Clone> Type<T> {
  |      ^
4 |     pub const fn f() {}
  |     ---------------- function declared as const here
  |
  = note: see issue rust-lang#57563 <rust-lang#57563> for more information
  = help: add `#![feature(const_fn_trait_bound)]` to the crate attributes to enable
```

---

I've originally wanted to point directly to `const` token, but couldn't find a way to get it's span. It seems like this span is lost during the AST -> HIR lowering.

Also, since the errors for object casts in `const fn`s (`&T` -> `&dyn Trait`) seem to trigger the same error, this PR accidentally changes these errors too. Not sure if it's desired or how to fix this.

P.S. it's my first time contributing to diagnostics, so feedback is very appreciated!

---

r? `@estebank`

`@rustbot` label: +A-diagnostics

`Wrapping<T>` has the same layout and ABI as `T`

Remove implementation of `min_align_of` intrinsic

Since rust-lang#88839 `min_align_of` is lowered to AlignOf operator.