…eneration method

It is only implemented for a single type. Directly passing this type is
simpler and avoids overhead from indirect calls.

It can be retrieved from the Session too.

They are not representable by Cranelift

…ypes on function signature.

Recommit after refactoring based on comment:
rust-lang#126017 (comment)

But when changing return type's lifetime to `ReError` will affect the subsequent borrow check process and cause test11 in typeck_type_placeholder_item.rs to lost E0515 message.
```rust
fn test11(x: &usize) -> &_ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
    &x //~ ERROR cannot return reference to function parameter(this E0515 msg will disappear)
}

```

…beta/stable channel

… `static` variable.

fixes rust-lang#126789

…ler-errors

Various rustc_codegen_ssa cleanups

Improve error message in tidy

The old error message was wrong (there is no `venv` Python package on PyPi), and we did not specify the correct Python path in the error message.

…-ozkan

Implement `x perf` as a separate tool

Continues work from rust-lang#126318, adds a CLI for running `rustc-perf` profiling commands through a new `rustc-perf-wrapper` tool. The CLI is in a separate tool to enable experimentation outside of `bootstrap`.

This is probably most of what we can do so far, I'll add support for benchmarking once `rustc-perf` gets a terminal output for comparing benchmark results.

r? `@onur-ozkan`

…-ozkan

Make mtime of reproducible tarballs dependent on git commit

Since rust-lang#123246, our tarballs should be fully reproducible. That means that the mtime of all files and directories in the tarballs is set to the date of the first Rust commit (from 2006). However, this is causing some mtime invalidation issues (rust-lang#125578 (comment)).

Ideally, we would like to keep the mtime reproducible, but still update it with new versions of Rust. That's what this PR does. It modifies the tarball installer bootstrap invocation so that if the current rustc directory is managed by git, we will set the UTC timestamp of the latest commit as the mtime for all files in the archive. This means that the archive should be still fully reproducible from a given commit SHA, but it will also be changed with new beta bumps and `download-rustc` versions.

Note that only files are set to this mtime, directories are still set to the year 2006, because the `tar` library used by `rust-installer` doesn't allow us to selectively override mtime for directories (or at least I haven't found it). We could work around that by doing all the mtime modifications in bootstrap, but that would require more changes. I think/hope that just modifying the file mtimes should be enough. It should at least fix cargo `rustc` mtime invalidation.

Fixes: rust-lang#125578

r? `@onur-ozkan`

Add a run-make test that LLD is not being used by default on the x64 beta/stable channel

rust-lang#126701 showed that the handling of `lld` in bootstrap is currently not ideal. While it would be nice to refactor it eventually, we should also make sure that we have a test that checks that `lld` is not used (yet!) by default on the x64 Linux stable channel.

CC `@lqd`

r? `@onur-ozkan`

…locks-diagnostics, r=compiler-errors

Improve unsafe extern blocks diagnostics

Closes rust-lang#126327

For this code:

```rust
extern {
    pub fn foo();
    pub safe fn bar();
}
```

We get ...

```
error: items in unadorned `extern` blocks cannot have safety qualifiers
 --> test.rs:3:5
  |
3 |     pub safe fn bar();
  |     ^^^^^^^^^^^^^^^^^^
  |
help: add unsafe to this `extern` block
  |
1 | unsafe extern {
  | ++++++

error[E0658]: `unsafe extern {}` blocks and `safe` keyword are experimental
 --> test.rs:3:9
  |
3 |     pub safe fn bar();
  |         ^^^^
  |
  = note: see issue rust-lang#123743 <rust-lang#123743> for more information
  = help: add `#![feature(unsafe_extern_blocks)]` to the crate attributes to enable

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0658`.
```

And then making the extern block unsafe, we get ...

```
error: extern block cannot be declared unsafe
 --> test.rs:1:1
  |
1 | unsafe extern {
  | ^^^^^^
  |
  = note: see issue rust-lang#123743 <rust-lang#123743> for more information
  = help: add `#![feature(unsafe_extern_blocks)]` to the crate attributes to enable

error: items in unadorned `extern` blocks cannot have safety qualifiers
 --> test.rs:3:5
  |
3 |     pub safe fn bar();
  |     ^^^^^^^^^^^^^^^^^^

error[E0658]: `unsafe extern {}` blocks and `safe` keyword are experimental
 --> test.rs:3:9
  |
3 |     pub safe fn bar();
  |         ^^^^
  |
  = note: see issue rust-lang#123743 <rust-lang#123743> for more information
  = help: add `#![feature(unsafe_extern_blocks)]` to the crate attributes to enable

error: aborting due to 3 previous errors

For more information about this error, try `rustc --explain E0658`.
```

r? `@compiler-errors`

…-errors

Fix a error suggestion for E0121 when using placeholder _ as return types on function signature.

Recommit after refactoring based on comment:
rust-lang#126017 (comment)

But when changing return type's lifetime to `ReError` will affect the subsequent borrow check process and cause test11 in typeck_type_placeholder_item.rs to lost E0515 message.
```rust
fn test11(x: &usize) -> &_ {
//~^ ERROR the placeholder `_` is not allowed within types on item signatures for return types
    &x //~ ERROR cannot return reference to function parameter(this E0515 msg will disappear)
}
```

fixes rust-lang#125488

r? `@pnkfelix`

fix: prefer `(*p).clone` to `p.clone` if the `p` is a raw pointer

Fixes rust-lang#126863

I wonder if there is a better way to solve the regression problem of this test case:
`tests/ui/borrowck/issue-20801.rs`.
It's okay to drop the dereference symbol in this scenario.

But it's not correct in rust-lang#126863

```
help: consider removing the dereference here
  |
5 -         let inner: String = *p;
5 +         let inner: String = p;
```

I haven't found out how to tell if clone pointer is allowed, i.e. no type mismatch occurs

Show `used attribute`'s kind for user when find it isn't applied to a `static` variable.

For example :
```rust
extern "C" {
    #[used] //~ ERROR attribute must be applied to a `static` variable
    static FOO: i32; // show the kind of this item to help user understand why the error is reported.
}
```

fixes rust-lang#126789