From 3c03d82c8489e0f408daa052760e5db651145ca2 Mon Sep 17 00:00:00 2001
From: beepster4096 <19316085+beepster4096@users.noreply.github.com>
Date: Sun, 18 Jan 2026 14:18:12 -0800
Subject: [PATCH 1/2] error on DuplicateHandle of pseudo handle

---
 src/tools/miri/src/shims/windows/handle.rs                  | 6 +++++-
 .../miri/tests/fail-dep/concurrency/windows_join_main.rs    | 2 +-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/tools/miri/src/shims/windows/handle.rs b/src/tools/miri/src/shims/windows/handle.rs
index 92d6321bed1f..b0d29bdd6f27 100644
--- a/src/tools/miri/src/shims/windows/handle.rs
+++ b/src/tools/miri/src/shims/windows/handle.rs
@@ -314,7 +314,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
                     "`DuplicateHandle` called on a thread handle, which is unsupported"
                 );
             }
-            Handle::Pseudo(pseudo) => Handle::Pseudo(pseudo),
+            Handle::Pseudo(_) => {
+                throw_unsup_format!(
+                    "`DuplicateHandle` called on a pseudo handle, which is unsupported"
+                );
+            }
             Handle::Null | Handle::Invalid => this.invalid_handle("DuplicateHandle")?,
         };
 
diff --git a/src/tools/miri/tests/fail-dep/concurrency/windows_join_main.rs b/src/tools/miri/tests/fail-dep/concurrency/windows_join_main.rs
index a71778b1d0d4..8c085384a688 100644
--- a/src/tools/miri/tests/fail-dep/concurrency/windows_join_main.rs
+++ b/src/tools/miri/tests/fail-dep/concurrency/windows_join_main.rs
@@ -12,7 +12,7 @@ use windows_sys::Win32::System::Threading::{INFINITE, WaitForSingleObject};
 
 // XXX HACK: This is how miri represents the handle for thread 0.
 // This value can be "legitimately" obtained by using `GetCurrentThread` with `DuplicateHandle`
-// but miri does not implement `DuplicateHandle` yet. (FIXME: it does now.)
+// but miri does not implement `DuplicateHandle` for pseudo handles yet.
 const MAIN_THREAD: HANDLE = (2i32 << 29) as HANDLE;
 
 fn main() {

From 7a937ae2395160fc74ca0c3f596f769ffe64ff40 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Sat, 24 Jan 2026 11:10:48 +0100
Subject: [PATCH 2/2] add test for DuplicateHandle on a pseudo handle

---
 .../fail-dep/win/duplicate-pseudo-handle.rs   | 22 +++++++++++++++++++
 .../win/duplicate-pseudo-handle.stderr        | 12 ++++++++++
 2 files changed, 34 insertions(+)
 create mode 100644 src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.rs
 create mode 100644 src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.stderr

diff --git a/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.rs b/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.rs
new file mode 100644
index 000000000000..c69ea419f7d2
--- /dev/null
+++ b/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.rs
@@ -0,0 +1,22 @@
+//@only-target: windows # Uses win32 api functions
+use windows_sys::Win32::Foundation::{CloseHandle, DUPLICATE_SAME_ACCESS, DuplicateHandle};
+use windows_sys::Win32::System::Threading::{GetCurrentProcess, GetCurrentThread};
+
+fn main() {
+    unsafe {
+        let cur_proc = GetCurrentProcess();
+
+        let pseudo = GetCurrentThread();
+        let mut out = std::mem::zeroed();
+        let res =
+            DuplicateHandle(cur_proc, pseudo, cur_proc, &mut out, 0, 0, DUPLICATE_SAME_ACCESS);
+        //~^ERROR: pseudo handle
+        assert!(res != 0);
+        assert!(out.addr() != 0);
+        // Since the original handle was a pseudo handle, we must return something different.
+        assert!(out != pseudo);
+        // And closing it should work (which it does not for a pseudo handle).
+        let res = CloseHandle(out);
+        assert!(res != 0);
+    }
+}
diff --git a/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.stderr b/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.stderr
new file mode 100644
index 000000000000..bbab2af67781
--- /dev/null
+++ b/src/tools/miri/tests/fail-dep/win/duplicate-pseudo-handle.stderr
@@ -0,0 +1,12 @@
+error: unsupported operation: `DuplicateHandle` called on a pseudo handle, which is unsupported
+  --> tests/fail-dep/win/duplicate-pseudo-handle.rs:LL:CC
+   |
+LL |             DuplicateHandle(cur_proc, pseudo, cur_proc, &mut out, 0, 0, DUPLICATE_SAME_ACCESS);
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ unsupported operation occurred here
+   |
+   = help: this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support
+
+note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
+
+error: aborting due to 1 previous error
+