Merge from rustc

Author: RalfJung

README.md

@@ -580,6 +580,7 @@ Definite bugs found:
 * [Weak-memory-induced memory leak in Windows thread-local storage](https://github.com/rust-lang/rust/pull/124281)
 * [A bug in the new `RwLock::downgrade` implementation](https://rust-lang.zulipchat.com/#narrow/channel/269128-miri/topic/Miri.20error.20library.20test) (caught by Miri before it landed in the Rust repo)
 * [Mockall reading unintialized memory when mocking `std::io::Read::read`, even if all expectations are satisfied](https://github.com/asomers/mockall/issues/647) (caught by Miri running Tokio's test suite)
+* [`ReentrantLock` not correctly dealing with reuse of addresses for TLS storage of different threads](https://github.com/rust-lang/rust/pull/141248)
 
 Violations of [Stacked Borrows] found that are likely bugs (but Stacked Borrows is currently just an experiment):
 

src/lib.rs

@@ -53,7 +53,7 @@ extern crate tracing;
 extern crate rustc_abi;
 extern crate rustc_apfloat;
 extern crate rustc_ast;
-extern crate rustc_attr_parsing;
+extern crate rustc_attr_data_structures;
 extern crate rustc_const_eval;
 extern crate rustc_data_structures;
 extern crate rustc_errors;

src/machine.rs

@@ -13,7 +13,7 @@ use rand::rngs::StdRng;
 use rand::{Rng, SeedableRng};
 use rustc_abi::{Align, ExternAbi, Size};
 use rustc_apfloat::{Float, FloatConvert};
-use rustc_attr_parsing::InlineAttr;
+use rustc_attr_data_structures::InlineAttr;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 #[allow(unused)]
 use rustc_data_structures::static_assert_size;

src/shims/native_lib.rs

@@ -92,8 +92,7 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
     fn get_func_ptr_explicitly_from_lib(&mut self, link_name: Symbol) -> Option<CodePtr> {
         let this = self.eval_context_mut();
         // Try getting the function from the shared library.
-        // On windows `_lib_path` will be unused, hence the name starting with `_`.
-        let (lib, _lib_path) = this.machine.native_lib.as_ref().unwrap();
+        let (lib, lib_path) = this.machine.native_lib.as_ref().unwrap();
         let func: libloading::Symbol<'_, unsafe extern "C" fn()> =
             unsafe { lib.get(link_name.as_str().as_bytes()).ok()? };
         #[expect(clippy::as_conversions)] // fn-ptr to raw-ptr cast needs `as`.
@@ -110,16 +109,17 @@ trait EvalContextExtPriv<'tcx>: crate::MiriInterpCxExt<'tcx> {
         // This code is a reimplementation of the mechanism for getting `dli_fname` in `libloading`,
         // from: https://docs.rs/libloading/0.7.3/src/libloading/os/unix/mod.rs.html#411
         // using the `libc` crate where this interface is public.
-        let mut info = std::mem::MaybeUninit::<libc::Dl_info>::uninit();
+        let mut info = std::mem::MaybeUninit::<libc::Dl_info>::zeroed();
         unsafe {
             if libc::dladdr(fn_ptr, info.as_mut_ptr()) != 0 {
                 let info = info.assume_init();
                 #[cfg(target_os = "cygwin")]
                 let fname_ptr = info.dli_fname.as_ptr();
                 #[cfg(not(target_os = "cygwin"))]
                 let fname_ptr = info.dli_fname;
+                assert!(!fname_ptr.is_null());
                 if std::ffi::CStr::from_ptr(fname_ptr).to_str().unwrap()
-                    != _lib_path.to_str().unwrap()
+                    != lib_path.to_str().unwrap()
                 {
                     return None;
                 }

tests/many-seeds/reentrant-lock.rs

@@ -0,0 +1,19 @@
+#![feature(reentrant_lock)]
+//! This is a regression test for
+//! <https://rust-lang.zulipchat.com/#narrow/channel/269128-miri/topic/reentrant.20lock.20failure.20on.20musl>.
+
+use std::cell::Cell;
+use std::sync::ReentrantLock;
+use std::thread;
+
+static LOCK: ReentrantLock<Cell<i32>> = ReentrantLock::new(Cell::new(0));
+
+fn main() {
+    for _ in 0..20 {
+        thread::spawn(move || {
+            let val = LOCK.lock();
+            val.set(val.get() + 1);
+            drop(val);
+        });
+    }
+}