allow "unraisable" warnings in nogil functions

Cython/Compiler/Code.py

@@ -2075,7 +2075,7 @@ class CCodeWriter(object):
         self.funcstate.uses_error_indicator = True
         self.putln('__Pyx_AddTraceback("%s", %s, %s, %s);' % format_tuple)
 
-    def put_unraisable(self, qualified_name):
+    def put_unraisable(self, qualified_name, nogil=False):
         """
         Generate code to print a Python warning for an unraisable exception.
 
@@ -2086,10 +2086,11 @@ class CCodeWriter(object):
             Naming.clineno_cname,
             Naming.lineno_cname,
             Naming.filename_cname,
-            int(self.globalstate.directives['unraisable_tracebacks'])
+            self.globalstate.directives['unraisable_tracebacks'],
+            nogil,
         )
         self.funcstate.uses_error_indicator = True
-        self.putln('__Pyx_WriteUnraisable("%s", %s, %s, %s, %s);' % format_tuple)
+        self.putln('__Pyx_WriteUnraisable("%s", %s, %s, %s, %d, %d);' % format_tuple)
         self.globalstate.use_utility_code(
             UtilityCode.load_cached("WriteUnraisableException", "Exceptions.c"))
 

Cython/Compiler/Nodes.py

@@ -1972,7 +1972,7 @@ class FuncDefNode(StatNode, BlockNode):
                 warning(self.entry.pos,
                         "Unraisable exception in function '%s'." %
                         self.entry.qualified_name, 0)
-                code.put_unraisable(self.entry.qualified_name)
+                code.put_unraisable(self.entry.qualified_name, lenv.nogil)
             default_retval = self.return_type.default_value
             if err_val is None and default_retval:
                 err_val = default_retval

Cython/Utility/Exceptions.c

@@ -414,16 +414,21 @@ static CYTHON_INLINE void __Pyx_ExceptionSwap(PyObject **type, PyObject **value,
 
 static void __Pyx_WriteUnraisable(const char *name, int clineno,
                                   int lineno, const char *filename,
-                                  int full_traceback); /*proto*/
+                                  int full_traceback, int nogil); /*proto*/
 
 /////////////// WriteUnraisableException ///////////////
 //@requires: PyErrFetchRestore
 
 static void __Pyx_WriteUnraisable(const char *name, CYTHON_UNUSED int clineno,
                                   CYTHON_UNUSED int lineno, CYTHON_UNUSED const char *filename,
-                                  int full_traceback) {
+                                  int full_traceback, CYTHON_UNUSED int nogil) {
     PyObject *old_exc, *old_val, *old_tb;
     PyObject *ctx;
+#ifdef WITH_THREAD
+    PyGILState_STATE state;
+    if (nogil)
+        state = PyGILState_Ensure();
+#endif
     __Pyx_ErrFetch(&old_exc, &old_val, &old_tb);
     if (full_traceback) {
         Py_XINCREF(old_exc);
@@ -444,6 +449,10 @@ static void __Pyx_WriteUnraisable(const char *name, CYTHON_UNUSED int clineno,
         PyErr_WriteUnraisable(ctx);
         Py_DECREF(ctx);
     }
+#ifdef WITH_THREAD
+    if (nogil)
+        PyGILState_Release(state);
+#endif
 }
 
 /////////////// AddTraceback.proto ///////////////

tests/run/nogil.pyx

+# mode: run
+
+try:
+    from StringIO import StringIO
+except ImportError:
+    from io import StringIO
+
+
 def test(int x):
     """
     >>> test(5)
@@ -35,3 +43,23 @@ def test_nogil_exception_propagation():
     """
     with nogil:
         nogil_func()
+
+
+cdef int write_unraisable() nogil:
+    with gil:
+        raise ValueError()
+
+
+def test_unraisable():
+    """
+    >>> print(test_unraisable())  # doctest: +ELLIPSIS
+    Exception...ignored...
+    """
+    import sys
+    old_stderr = sys.stderr
+    stderr = sys.stderr = StringIO()
+    try:
+        write_unraisable()
+    finally:
+        sys.stderr = old_stderr
+    return stderr.getvalue().strip()