Auto merge of #115746 - tgross35:unnamed-threads-panic-message, r=<try>

Print thread ID in panic message

`panic!` does not print any identifying information for threads that are
unnamed. However, in many cases, the thread ID can be determined.

This changes the panic message from something like this:

    thread '<unnamed>' panicked at src/main.rs:3:5:
    explicit panic

To something like this:

    thread '<unnamed>' (12345) panicked at src/main.rs:3:5:
    explicit panic

Stack overflow messages are updated as well.

This change applies to both named and unnamed threads. The ID printed is
the OS integer thread ID rather than the Rust thread ID, which should
also be what debuggers print.

try-job: `*various*`
try-job: `x86_64-msvc*`

Author: rust-bors[bot]

library/std/src/panicking.rs

@@ -269,6 +269,7 @@ fn default_hook(info: &PanicHookInfo<'_>) {
 
         thread::with_current_name(|name| {
             let name = name.unwrap_or("<unnamed>");
+            let tid = thread::current_os_id();
 
             // Try to write the panic message to a buffer first to prevent other concurrent outputs
             // interleaving with it.
@@ -277,7 +278,7 @@ fn default_hook(info: &PanicHookInfo<'_>) {
 
             let write_msg = |dst: &mut dyn crate::io::Write| {
                 // We add a newline to ensure the panic message appears at the start of a line.
-                writeln!(dst, "\nthread '{name}' panicked at {location}:\n{msg}")
+                writeln!(dst, "\nthread '{name}' ({tid}) panicked at {location}:\n{msg}")
             };
 
             if write_msg(&mut cursor).is_ok() {

library/std/src/sys/pal/hermit/thread.rs

@@ -103,6 +103,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     unsafe { Ok(NonZero::new_unchecked(hermit_abi::available_parallelism())) }
 }

library/std/src/sys/pal/itron/thread.rs

@@ -349,6 +349,10 @@ unsafe fn terminate_and_delete_current_task() -> ! {
     unsafe { crate::hint::unreachable_unchecked() };
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     super::unsupported()
 }

library/std/src/sys/pal/sgx/thread.rs

@@ -137,6 +137,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     unsupported()
 }

library/std/src/sys/pal/teeos/thread.rs

@@ -132,6 +132,10 @@ impl Drop for Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 // Note: Both `sched_getaffinity` and `sysconf` are available but not functional on
 // teeos, so this function always returns an Error!
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {

library/std/src/sys/pal/uefi/thread.rs

@@ -44,6 +44,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     // UEFI is single threaded
     Ok(NonZero::new(1).unwrap())

library/std/src/sys/pal/unix/stack_overflow.rs

@@ -120,7 +120,8 @@ mod imp {
                     && thread_info.guard_page_range.contains(&fault_addr)
                 {
                     let name = thread_info.thread_name.as_deref().unwrap_or("<unknown>");
-                    rtprintpanic!("\nthread '{name}' has overflowed its stack\n");
+                    let tid = crate::thread::current_os_id();
+                    rtprintpanic!("\nthread '{name}' ({tid}) has overflowed its stack\n");
                     rtabort!("stack overflow");
                 }
             })
@@ -696,7 +697,8 @@ mod imp {
             if code == c::EXCEPTION_STACK_OVERFLOW {
                 crate::thread::with_current_name(|name| {
                     let name = name.unwrap_or("<unknown>");
-                    rtprintpanic!("\nthread '{name}' has overflowed its stack\n");
+                    let tid = crate::thread::current_os_id();
+                    rtprintpanic!("\nthread '{name}' ({tid}) has overflowed its stack\n");
                 });
             }
             c::EXCEPTION_CONTINUE_SEARCH

library/std/src/sys/pal/unix/thread.rs

@@ -318,6 +318,44 @@ impl Drop for Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    // Most Unix platforms have a way to query an integer ID of the current thread, all with
+    // slightly different spellings.
+    cfg_if::cfg_if! {
+        // Most platforms have a function returning a `pid_t` or int, which is an `i32`.
+        if #[cfg(any(target_os = "android", target_os = "linux", target_os = "nto"))] {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pid_t = unsafe { libc::gettid() };
+            Some(id as u64)
+        } else if #[cfg(target_os = "openbsd")] {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::pid_t = unsafe { libc::getthrid() };
+            Some(id as u64)
+        } else if #[cfg(target_os = "freebsd")] {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::c_int = unsafe { libc::pthread_getthreadid_np() };
+            Some(id as u64)
+        } else if #[cfg(target_os = "netbsd")] {
+            // SAFETY: FFI call with no preconditions.
+            let id: libc::lwpid_t = unsafe { libc::_lwp_self() };
+            Some(id as u64)
+        } else if #[cfg(target_vendor = "apple")] {
+            // Apple allows querying arbitrary thread IDs, `thread=NULL` queries the current thread.
+            let mut id = 0u64;
+            // SAFETY: `thread_id` is a valid pointer, no other preconditions.
+            let status: libc::c_int = unsafe { libc::pthread_threadid_np(0, &mut id) };
+            if status == 0 {
+                Some(id)
+            } else {
+                None
+            }
+        } else {
+            // Other platforms don't have an OS thread ID or don't have a way to access it.
+            None
+        }
+    }
+}
+
 #[cfg(any(
     target_os = "linux",
     target_os = "nto",

library/std/src/sys/pal/unsupported/thread.rs

@@ -31,6 +31,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     unsupported()
 }

library/std/src/sys/pal/wasi/thread.rs

@@ -186,6 +186,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     cfg_if::cfg_if! {
         if #[cfg(target_feature = "atomics")] {

library/std/src/sys/pal/windows/c/bindings.txt

@@ -2177,6 +2177,7 @@ GetSystemInfo
 GetSystemTimeAsFileTime
 GetSystemTimePreciseAsFileTime
 GetTempPathW
+GetThreadId
 GetUserProfileDirectoryW
 GetWindowsDirectoryW
 HANDLE

library/std/src/sys/pal/windows/c/windows_sys.rs

@@ -61,6 +61,7 @@ windows_targets::link!("kernel32.dll" "system" fn GetSystemInfo(lpsysteminfo : *
 windows_targets::link!("kernel32.dll" "system" fn GetSystemTimeAsFileTime(lpsystemtimeasfiletime : *mut FILETIME));
 windows_targets::link!("kernel32.dll" "system" fn GetSystemTimePreciseAsFileTime(lpsystemtimeasfiletime : *mut FILETIME));
 windows_targets::link!("kernel32.dll" "system" fn GetTempPathW(nbufferlength : u32, lpbuffer : PWSTR) -> u32);
+windows_targets::link!("kernel32.dll" "system" fn GetThreadId(thread : HANDLE) -> u32);
 windows_targets::link!("userenv.dll" "system" fn GetUserProfileDirectoryW(htoken : HANDLE, lpprofiledir : PWSTR, lpcchsize : *mut u32) -> BOOL);
 windows_targets::link!("kernel32.dll" "system" fn GetWindowsDirectoryW(lpbuffer : PWSTR, usize : u32) -> u32);
 windows_targets::link!("kernel32.dll" "system" fn InitOnceBeginInitialize(lpinitonce : *mut INIT_ONCE, dwflags : u32, fpending : *mut BOOL, lpcontext : *mut *mut core::ffi::c_void) -> BOOL);

library/std/src/sys/pal/windows/stack_overflow.rs

@@ -20,7 +20,8 @@ unsafe extern "system" fn vectored_handler(ExceptionInfo: *mut c::EXCEPTION_POIN
         if code == c::EXCEPTION_STACK_OVERFLOW {
             thread::with_current_name(|name| {
                 let name = name.unwrap_or("<unknown>");
-                rtprintpanic!("\nthread '{name}' has overflowed its stack\n");
+                let tid = thread::current_os_id();
+                rtprintpanic!("\nthread '{name}' ({tid}) has overflowed its stack\n");
             });
         }
         c::EXCEPTION_CONTINUE_SEARCH

library/std/src/sys/pal/windows/thread.rs

@@ -115,6 +115,14 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    // SAFETY: FFI call with no preconditions.
+    let id: u32 = unsafe { c::GetThreadId(c::GetCurrentThread()) };
+
+    // A return value of 0 indicates failed lookup.
+    if id == 0 { None } else { Some(id.into()) }
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     let res = unsafe {
         let mut sysinfo: c::SYSTEM_INFO = crate::mem::zeroed();

library/std/src/sys/pal/xous/thread.rs

@@ -133,6 +133,10 @@ impl Thread {
     }
 }
 
+pub(crate) fn current_os_id() -> Option<u64> {
+    None
+}
+
 pub fn available_parallelism() -> io::Result<NonZero<usize>> {
     // We're unicore right now.
     Ok(unsafe { NonZero::new_unchecked(1) })

library/std/src/thread/current.rs

@@ -1,4 +1,4 @@
-use super::{Thread, ThreadId};
+use super::{Thread, ThreadId, imp};
 use crate::mem::ManuallyDrop;
 use crate::ptr;
 use crate::sys::thread_local::local_pointer;
@@ -148,6 +148,16 @@ pub(crate) fn current_id() -> ThreadId {
     id::get_or_init()
 }
 
+/// Gets the OS thread ID of the thread that invokes it, if available. If not, return the Rust
+/// thread ID.
+///
+/// We use a `u64` to fit either integer or pointer IDs on all platforms without excess `cfg`. This
+/// is a "best effort" approach for diagnostics and is allowed to fall back to a non-OS ID (such as
+/// the Rust thread ID) or a non-unique ID (such as a PID) if the thread ID cannot be retrieved.
+pub(crate) fn current_os_id() -> u64 {
+    imp::current_os_id().unwrap_or_else(|| current_id().as_u64().get())
+}
+
 /// Gets a reference to the handle of the thread that invokes it, if the handle
 /// has been initialized.
 pub(super) fn try_with_current<F, R>(f: F) -> R

library/std/src/thread/mod.rs

@@ -183,7 +183,7 @@ mod current;
 
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use current::current;
-pub(crate) use current::{current_id, current_or_unnamed, drop_current};
+pub(crate) use current::{current_id, current_or_unnamed, current_os_id, drop_current};
 use current::{set_current, try_with_current};
 
 mod spawnhook;

library/std/src/thread/tests.rs

@@ -346,6 +346,13 @@ fn test_thread_id_not_equal() {
     assert!(thread::current().id() != spawned_id);
 }
 
+#[test]
+fn test_thread_os_id_not_equal() {
+    let spawned_id = thread::spawn(|| thread::current_os_id()).join().unwrap();
+    let current_id = thread::current_os_id();
+    assert!(current_id != spawned_id);
+}
+
 #[test]
 fn test_scoped_threads_drop_result_before_join() {
     let actually_finished = &AtomicBool::new(false);

src/tools/compiletest/src/runtest.rs

@@ -2413,6 +2413,11 @@ impl<'test> TestCx<'test> {
                 })
                 .into_owned();
 
+        // Normalize thread IDs in panic messages
+        normalized = static_regex!(r"thread '(?P<name>.*?)' \(\d+\) panicked")
+            .replace_all(&normalized, "thread '$name' ($$TID) panicked")
+            .into_owned();
+
         normalized = normalized.replace("\t", "\\t"); // makes tabs visible
 
         // Remove test annotations like `//~ ERROR text` from the output,

src/tools/miri/src/shims/env.rs

@@ -110,8 +110,29 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         }
     }
 
+    /// Get the process identifier.
     fn get_pid(&self) -> u32 {
         let this = self.eval_context_ref();
         if this.machine.communicate() { std::process::id() } else { 1000 }
     }
+
+    /// Get an "OS" thread ID for the current thread.
+    fn get_current_tid(&self) -> u32 {
+        self.get_tid(self.eval_context_ref().machine.threads.active_thread())
+    }
+
+    /// Get an "OS" thread ID for any thread.
+    fn get_tid(&self, thread: ThreadId) -> u32 {
+        let this = self.eval_context_ref();
+        let index = thread.to_u32();
+        let target_os = &this.tcx.sess.target.os;
+        if target_os == "linux" || target_os == "netbsd" {
+            // On Linux, the main thread has PID == TID so we uphold this. NetBSD also appears
+            // to exhibit the same behavior, though I can't find a citation.
+            this.get_pid().strict_add(index)
+        } else {
+            // Other platforms do not document any relationship between PID and TID.
+            index
+        }
+    }
 }

src/tools/miri/src/shims/unix/env.rs

@@ -7,6 +7,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_index::IndexVec;
 use rustc_middle::ty::Ty;
 use rustc_middle::ty::layout::LayoutOf;
+use rustc_span::Symbol;
 
 use crate::*;
 
@@ -275,15 +276,56 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
         interp_ok(Scalar::from_u32(this.get_pid()))
     }
 
-    fn linux_gettid(&mut self) -> InterpResult<'tcx, Scalar> {
+    /// The `gettid`-like function for Unix platforms that take no parameters and return a 32-bit
+    /// integer. It is not always named "gettid".
+    fn unix_gettid(&mut self, link_name: Symbol) -> InterpResult<'tcx, Scalar> {
         let this = self.eval_context_ref();
-        this.assert_target_os("linux", "gettid");
+        let target_os = &self.eval_context_ref().tcx.sess.target.os;
+
+        // Various platforms have a similar function with different names.
+        match (target_os.as_ref(), link_name.as_str()) {
+            ("linux" | "android", "gettid") => (),
+            ("openbsd", "getthrid") => (),
+            ("freebsd", "pthread_getthreadid_np") => (),
+            ("netbsd", "_lwp_self") => (),
+            (_, name) => panic!("`{name}` is not supported on {target_os}"),
+        };
+
+        // For most platforms the return type is an `i32`, but some are unsigned. The TID
+        // will always be positive so we don't need to differentiate.
+        interp_ok(Scalar::from_u32(this.get_current_tid()))
+    }
 
-        let index = this.machine.threads.active_thread().to_u32();
+    /// The Apple-specific `int pthread_threadid_np(pthread_t thread, uint64_t *thread_id)`, which
+    /// allows querying the ID for arbitrary threads.
+    fn apple_pthread_threadip_np(
+        &mut self,
+        thread_op: &OpTy<'tcx>,
+        tid_op: &OpTy<'tcx>,
+    ) -> InterpResult<'tcx, Scalar> {
+        let this = self.eval_context_mut();
+
+        let target_vendor = &this.tcx.sess.target.vendor;
+        assert_eq!(
+            target_vendor, "apple",
+            "`pthread_threadid_np` is not supported on target vendor {target_vendor}",
+        );
+
+        let thread = this.read_scalar(thread_op)?.to_int(this.libc_ty_layout("pthread_t").size)?;
+        let thread = if thread == 0 {
+            // Null thread ID indicates that we are querying the active thread.
+            this.machine.threads.active_thread()
+        } else {
+            let Ok(thread) = this.thread_id_try_from(thread) else {
+                return interp_ok(this.eval_libc("ESRCH"));
+            };
+            thread
+        };
 
-        // Compute a TID for this thread, ensuring that the main thread has PID == TID.
-        let tid = this.get_pid().strict_add(index);
+        let tid_dest = this.deref_pointer_as(tid_op, this.machine.layouts.u64)?;
+        this.write_int(this.get_tid(thread), &tid_dest)?;
 
-        interp_ok(Scalar::from_u32(tid))
+        // Never an error if we only ever check the current thread.
+        interp_ok(Scalar::from_u32(0))
     }
 }

src/tools/miri/src/shims/unix/freebsd/foreign_items.rs

@@ -56,6 +56,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                 };
                 this.write_scalar(res, dest)?;
             }
+            "pthread_getthreadid_np" => {
+                let [] = this.check_shim(abi, CanonAbi::C, link_name, args)?;
+                let result = this.unix_gettid(link_name)?;
+                this.write_scalar(result, dest)?;
+            }
 
             "cpuset_getaffinity" => {
                 // The "same" kind of api as `sched_getaffinity` but more fine grained control for FreeBSD specifically.

src/tools/miri/src/shims/unix/linux/foreign_items.rs

@@ -117,7 +117,7 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
             }
             "gettid" => {
                 let [] = this.check_shim(abi, CanonAbi::C, link_name, args)?;
-                let result = this.linux_gettid()?;
+                let result = this.unix_gettid(link_name)?;
                 this.write_scalar(result, dest)?;
             }