Rollup merge of #146281 - Jules-Bertholet:static-align-thread-local, r=Mark-Simulacrum

Support `#[rustc_align_static]` inside `thread_local!`

Tracking issue: rust-lang/rust#146177

```rust
thread_local! {
    #[rustc_align_static(64)]
    static SO_ALIGNED: u64 = const { 0 };
}
```

This increases the amount of recursion the macro performs (once per attribute in addition to the previous once per item), making it easier to hit the recursion limit. I’ve added workarounds to limit the impact in the case of long doc comments, but this still needs a crater run just in case.

r? libs

``@rustbot`` label A-attributes A-macros A-thread-locals F-static_align T-libs

1 files changed, 57 insertions, 0 deletions

diff --git a/tests/ui/thread-local/no-unstable.stderr b/tests/ui/thread-local/no-unstable.stderr
new file mode 100644
index 00000000000..fbcd804d917
--- /dev/null
+++ b/tests/ui/thread-local/no-unstable.stderr
@@ -0,0 +1,57 @@
+error[E0658]: use of an internal attribute
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+   = note: the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_dummy]` attribute is used for rustc unit tests
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0658]: use of an internal attribute
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: add `#![feature(rustc_attrs)]` to the crate attributes to enable
+   = note: the `#[rustc_dummy]` attribute is an internal implementation detail that will never be stable
+   = note: the `#[rustc_dummy]` attribute is used for rustc unit tests
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0658]: `#[used(linker)]` is currently unstable
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = note: see issue #93798 <https://github.com/rust-lang/rust/issues/93798> for more information
+   = help: add `#![feature(used_with_arg)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: `#[used]` attribute cannot be used on constants
+  --> $DIR/no-unstable.rs:1:1
+   |
+LL | / thread_local! {
+...  |
+LL | |     pub static BAZ: () = ();
+LL | | }
+   | |_^
+   |
+   = help: `#[used]` can only be applied to statics
+   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_process_attrs` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0658`.