Use the trashcan for Gen

Author: jdemeyer

cypari2/gen.pxd

@@ -1,3 +1,4 @@
+cimport cython
 from cpython.object cimport PyObject
 from .types cimport GEN, pari_sp
 

cypari2/gen.pyx

@@ -141,6 +141,7 @@ cdef extern from *:
     GEN old_nfbasis(GEN x, GEN * y, GEN p)
 
 
+@cython.trashcan(True)
 cdef class Gen(Gen_base):
     """
     Wrapper for a PARI ``GEN`` with memory management.

cypari2/pari_instance.pyx

@@ -243,6 +243,15 @@ Reset default precision for the following tests:
 
 >>> pari.set_real_precision_bits(53)
 
+Test the trashcan mechanism (without the trashcan, this would cause
+a stack overflow):
+
+>>> pari.allocatemem(2**27, silent=True)
+>>> L = [pari(i) for i in range(2**20)]
+>>> x = pari.Pi()
+>>> del L
+>>> del x
+
 Test that interrupts work properly:
 
 >>> pari.allocatemem(8000000, 2**29)