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

6 files changed, 434 insertions, 3 deletions

diff --git a/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs b/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs
new file mode 100644
index 00000000000..29d4facffce
--- /dev/null
+++ b/tests/ui/feature-gates/feature-gate-static_align-thread_local.rs
@@ -0,0 +1,11 @@
+// The feature gate error may be emitted twice, but only on certain targets
+//@ dont-require-annotations: ERROR
+//@ dont-check-compiler-stderr
+
+#![crate_type = "lib"]
+
+thread_local! {
+    //~^ ERROR the `#[rustc_align_static]` attribute is an experimental feature
+    #[rustc_align_static(16)]
+    static THREAD_LOCAL: u16 = 0;
+}
diff --git a/tests/ui/macros/macro-local-data-key-priv.stderr b/tests/ui/macros/macro-local-data-key-priv.stderr
index e93bd11046d..8df1aec140d 100644
--- a/tests/ui/macros/macro-local-data-key-priv.stderr
+++ b/tests/ui/macros/macro-local-data-key-priv.stderr
@@ -9,7 +9,7 @@ note: the constant `baz` is defined here
    |
 LL |     thread_local!(static baz: f64 = 0.0);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   = note: this error originates in the macro `$crate::thread::local_impl::thread_local_inner` which comes from the expansion of the macro `thread_local` (in Nightly builds, run with -Z macro-backtrace for more info)
+   = note: this error originates in the macro `$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 1 previous error
 
diff --git a/tests/ui/static/static-align.rs b/tests/ui/static/static-align.rs
index 93241db09f9..e2db7c01adf 100644
--- a/tests/ui/static/static-align.rs
+++ b/tests/ui/static/static-align.rs
@@ -1,10 +1,14 @@
 //@ run-pass
+//@ compile-flags: --cfg FOURTY_TWO="42" --cfg TRUE --check-cfg=cfg(FOURTY_TWO,values("42")) --check-cfg=cfg(TRUE)
 #![feature(static_align)]
+#![deny(non_upper_case_globals)]
+
+use std::cell::Cell;
 
 #[rustc_align_static(64)]
 static A: u8 = 0;
 
-#[rustc_align_static(64)]
+#[rustc_align_static(4096)]
 static B: u8 = 0;
 
 #[rustc_align_static(128)]
@@ -17,10 +21,86 @@ unsafe extern "C" {
     static C: u64;
 }
 
+struct HasDrop(*const HasDrop);
+
+impl Drop for HasDrop {
+    fn drop(&mut self) {
+        assert_eq!(core::ptr::from_mut(self).cast_const(), self.0);
+    }
+}
+
+thread_local! {
+    #[rustc_align_static(4096)]
+    static LOCAL: u64 = 0;
+
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(true, rustc_align_static(4096))]
+    static CONST_LOCAL: u64 = const { 0 };
+
+    #[cfg_attr(any(true), cfg_attr(true, rustc_align_static(4096)))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    static HASDROP_LOCAL: Cell<HasDrop> = Cell::new(HasDrop(core::ptr::null()));
+
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    #[allow(unused_mut, reason = "test attribute handling")]
+    #[cfg_attr(TRUE,
+      cfg_attr(FOURTY_TWO = "42",
+      cfg_attr(all(),
+      cfg_attr(any(true),
+      cfg_attr(true, rustc_align_static(4096))))))]
+    #[allow(unused_mut, reason = "test attribute handling")]
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    static HASDROP_CONST_LOCAL: Cell<HasDrop> = const { Cell::new(HasDrop(core::ptr::null())) };
+
+    #[cfg_attr(TRUE,)]
+    #[cfg_attr(true,)]
+    #[cfg_attr(false,)]
+    #[cfg_attr(
+        TRUE,
+        rustc_align_static(32),
+        cfg_attr(true, allow(non_upper_case_globals, reason = "test attribute handling")),
+        cfg_attr(false,)
+    )]
+    #[cfg_attr(false, rustc_align_static(0))]
+    static more_attr_testing: u64 = 0;
+}
+
+fn thread_local_ptr<T>(key: &'static std::thread::LocalKey<T>) -> *const T {
+    key.with(|local| core::ptr::from_ref::<T>(local))
+}
+
 fn main() {
     assert!(core::ptr::from_ref(&A).addr().is_multiple_of(64));
-    assert!(core::ptr::from_ref(&B).addr().is_multiple_of(64));
+    assert!(core::ptr::from_ref(&B).addr().is_multiple_of(4096));
 
     assert!(core::ptr::from_ref(&EXPORTED).addr().is_multiple_of(128));
     unsafe { assert!(core::ptr::from_ref(&C).addr().is_multiple_of(128)) };
+
+    assert!(thread_local_ptr(&LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&HASDROP_CONST_LOCAL).addr().is_multiple_of(4096));
+    assert!(thread_local_ptr(&more_attr_testing).addr().is_multiple_of(32));
+
+    // Test that address (and therefore alignment) is maintained during drop
+    let hasdrop_ptr = thread_local_ptr(&HASDROP_LOCAL);
+    core::mem::forget(HASDROP_LOCAL.replace(HasDrop(hasdrop_ptr.cast())));
+    let hasdrop_const_ptr = thread_local_ptr(&HASDROP_CONST_LOCAL);
+    core::mem::forget(HASDROP_CONST_LOCAL.replace(HasDrop(hasdrop_const_ptr.cast())));
 }
diff --git a/tests/ui/thread-local/long-docs.rs b/tests/ui/thread-local/long-docs.rs
new file mode 100644
index 00000000000..0577d0b27c2
--- /dev/null
+++ b/tests/ui/thread-local/long-docs.rs
@@ -0,0 +1,266 @@
+//@ check-pass
+
+thread_local! {
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    pub static LONG_DOCS: () = ();
+
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    /// I love doc comments.
+    #[allow(unused_mut, reason = "testing")]
+    pub static LONG_DOCS_2: () = ();
+}
+
+fn main() {}
diff --git a/tests/ui/thread-local/no-unstable.rs b/tests/ui/thread-local/no-unstable.rs
new file mode 100644
index 00000000000..3de7985e62d
--- /dev/null
+++ b/tests/ui/thread-local/no-unstable.rs
@@ -0,0 +1,17 @@
+thread_local! {
+    //~^ ERROR: use of an internal attribute [E0658]
+    //~| ERROR: use of an internal attribute [E0658]
+    //~| ERROR: `#[used(linker)]` is currently unstable [E0658]
+    //~| ERROR: `#[used]` attribute cannot be used on constants
+
+    #[rustc_dummy = 17]
+    pub static FOO: () = ();
+
+    #[cfg_attr(true, rustc_dummy = 17)]
+    pub static BAR: () = ();
+
+    #[used(linker)]
+    pub static BAZ: () = ();
+}
+
+fn main() {}
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`.