std: Attempt again to inline thread-local-init across crates

Issue #25088 has been part of `thread_local!` for quite some time now.
Historical attempts have been made to add `#[inline]` to `__getit`
in #43931, #50252, and #59720, but these attempts ended up not landing
at the time due to segfaults on Windows.

In the interim though with `const`-initialized thread locals AFAIK this
is the only remaining bug which is why you might want to use
`#[thread_local]` over `thread_local!`. As a result I figured it was
time to resubmit this and see how it fares on CI and if I can help
debugging any issues that crop up.

Closes #25088

1 files changed, 6 insertions, 0 deletions

diff --git a/src/test/codegen/auxiliary/thread_local_aux.rs b/src/test/codegen/auxiliary/thread_local_aux.rs
new file mode 100644
index 00000000000..29b5e3ca244
--- /dev/null
+++ b/src/test/codegen/auxiliary/thread_local_aux.rs
@@ -0,0 +1,6 @@
+#![crate_type = "lib"]
+#![feature(thread_local_const_init)]
+
+use std::cell::Cell;
+
+thread_local!(pub static A: Cell<u64> = const { Cell::new(0) });