> Here is a failing testcase. I was about to post the same test. The test fails with two counts: (1) len(P) == 80, (2) deallocate(P) fails with
a.out(882,0x7fff75e1d310) malloc: *** error for object 0x7fc801c04978: incorrect checksum for freed object - object was probably modified after being freed. ... Dominique