The following example program leaks memory like a sieve (because the GC is disabled).  Apparently, std.regex.match() is not supposed to perform heap allocations.

import std.regex, core.memory;

void main() {
    string s = "This is only a test.  Repeat, this is only a test.";
    auto r = regex("is.only");

    GC.disable;
    while(true) {
        auto m = match(s, r);
    }
}