new attempt

pyo3-ffi/Cargo.toml

@@ -14,6 +14,7 @@ rust-version = "1.63"
 
 [dependencies]
 libc = "0.2.62"
+rustversion = "1"
 
 [features]
 
@@ -42,7 +43,6 @@ generate-import-lib = ["pyo3-build-config/python3-dll-a"]
 paste = "1"
 
 [build-dependencies]
-cc = "1.2"
 pyo3-build-config = { path = "../pyo3-build-config", version = "=0.23.3", features = ["resolve-config"] }
 
 [lints]

pyo3-ffi/build.rs

@@ -182,19 +182,6 @@ fn emit_link_config(interpreter_config: &InterpreterConfig) -> Result<()> {
     Ok(())
 }
 
-fn do_cc(interpreter_config: &InterpreterConfig) {
-    let implementation_def = match interpreter_config.implementation {
-        PythonImplementation::CPython => "PYTHON_IS_CPYTHON",
-        PythonImplementation::PyPy => "PYTHON_IS_PYPY",
-        PythonImplementation::GraalPy => "PYTHON_IS_GRAALPY",
-    };
-    println!("cargo:rerun-if-changed=src/acquire_gil.cpp");
-    cc::Build::new()
-        .file("src/acquire_gil.c")
-        .define(implementation_def, None)
-        .compile("acquire_gil");
-}
-
 /// Prepares the PyO3 crate for compilation.
 ///
 /// This loads the config from pyo3-build-config and then makes some additional checks to improve UX
@@ -231,8 +218,6 @@ fn configure_pyo3() -> Result<()> {
     // Emit cfgs like `invalid_from_utf8_lint`
     print_feature_cfgs();
 
-    do_cc(&interpreter_config);
-
     Ok(())
 }
 

pyo3-ffi/src/pystate.rs

@@ -73,15 +73,50 @@ pub enum PyGILState_STATE {
     PyGILState_UNLOCKED,
 }
 
+struct HangThread;
+
+impl Drop for HangThread {
+    fn drop(&mut self) {
+        loop {
+            #[cfg(target_family = "unix")]
+            unsafe {
+                libc::pause();
+            }
+            #[cfg(not(target_family = "unix"))]
+            std::thread::sleep(std::time::Duration::from_secs(9_999_999));
+        }
+    }
+}
+
+// The PyGILState_Ensure function will call pthread_exit during interpreter shutdown,
+// which causes undefined behavior. Redirect to the "safe" version that hangs instead,
+// as Python 3.14 does.
+//
+// See https://github.com/rust-lang/rust/issues/135929
+
+// C-unwind only supported (and necessary) since 1.71
+mod raw {
+    #[rustversion::since(1.71)]
+    extern "C-unwind" {
+        #[cfg_attr(PyPy, link_name = "PyPyGILState_Ensure")]
+        pub fn PyGILState_Ensure() -> super::PyGILState_STATE;
+    }
+
+    #[rustversion::before(1.71)]
+    extern "C" {
+        #[cfg_attr(PyPy, link_name = "PyPyGILState_Ensure")]
+        pub fn PyGILState_Ensure() -> super::PyGILState_STATE;
+    }
+}
+
+pub unsafe extern "C" fn PyGILState_Ensure() -> PyGILState_STATE {
+    let guard = HangThread;
+    let ret: PyGILState_STATE = raw::PyGILState_Ensure();
+    std::mem::forget(guard);
+    ret
+}
+
 extern "C" {
-    // The PyGILState_Ensure function will call pthread_exit during interpreter shutdown,
-    // which causes undefined behavior. Redirect to the "safe" version that hangs instead,
-    // as Python 3.14 does.
-    //
-    // See https://github.com/rust-lang/rust/issues/135929
-    #[cfg_attr(PyPy, link_name = "PyPyGILState_Ensure_Safe")]
-    #[cfg_attr(not(PyPy), link_name = "PyGILState_Ensure_Safe")]
-    pub fn PyGILState_Ensure() -> PyGILState_STATE;
     #[cfg_attr(PyPy, link_name = "PyPyGILState_Release")]
     pub fn PyGILState_Release(arg1: PyGILState_STATE);
     #[cfg(not(PyPy))]