To avoid the risk outlined here, knowing all the references to a variable is not sufficient; without an understanding of their lifetimes in every possible permu

To avoid the risk outlined here, knowing all the references to a variable is not sufficient; without an understanding of their lifetimes in every possible permutation of the program's use (and misuse), you cannot act on that information to minimize the exposure posited here. I won't get into the question of whether a programmer should also know all that, as there is another consideration which renders it moot: Even with a non-GC'd language, a programmer could leave variables with sensitive information in memory for the remaining duration of the program (e.g. local variables left deep in the stack when a function returns or throws an exception - do you know when they will be overwritten?) What matters here is that the programmer understands the risks, knows what constitutes the most sensitive data, and acts accordingly - but, armed with that knowledge, the programmer can just as well ameliorate the risk in a GC'd language as one that is not.