It would be nice if there was a way to tell compilers not to drop the lock stack and thus issue warnings when accessing a symbol that needs a lock inside `Assume`/`Assert`.

Hit by (at least): @ajtowns , @jnewbery , me.
{
    BOOST_CHECK(TimingResistantEqual(std::string(""), std::string("")));
    BOOST_CHECK(!TimingResistantEqual(std::string("abc"), std::string("")));
    BOOST_CHECK(!TimingResistantEqual(std::string(""), std::string("abc")));
    BOOST_CHECK(!TimingResistantEqual(std::string("a"), std::string("aa")));
    BOOST_CHECK(!TimingResistantEqual(std::string("aa"), std::string("a")));
    BOOST_CHECK(TimingResistantEqual(std::string("abc"), std::string("abc")));
    BOOST_CHECK(!TimingResistantEqual(std::string("abc"), std::string("aba")));
}
/* Test strprintf formatting directives.
 * Put a string before and after to ensure sanity of element sizes on stack. */
#define B "check_prefix"
#define E "check_postfix"
BOOST_AUTO_TEST_CASE(strprintf_numbers)