I am experiencing problems that appear to be in std::variant. I wonder
if this has been reported before, and I just need to upgrade.
The problem appears to be in this switch:
class number_t {
enum type_t { int_e, float_e };
std::variant<ssize_t, double> value;
public:
...
number_t& operator=( const number_t& that ) {
assert( that.value.index() != std::variant_npos );
switch( type_t(that.value.index()) ) {
case int_e: value = std::get<ssize_t>(that.value); break;
case float_e: value = std::get<double>(that.value); break;
}
return *this;
}
That's not how I wrote the code originally. That's a re-write to try to
isolate the problem.
valgrind reports:
==999106== Conditional jump or move depends on uninitialised value(s)
==999106== at 0x1130B8: number_t::operator=(number_t const&)
(expression.h:80)
==999106== by 0x123C23: env_t::numop(number_t& (*)(number_t&, exp_t const&),
exp_t const&) (core.cc:429)
==999106== by 0x123FA3: env_t::mul(exp_t const&, env_t&) (core.cc:457)
==999106== by 0x12286F: env_t::eval(exp_t const&, env_t&) (core.cc:148)
==999106== by 0x122767: env_t::eval(exp_t const&, env_t&) (core.cc:136)
==999106== by 0x1104EB: yyparse() (parse.y:319)
==999106== by 0x12DF3F: repl() (main.cc:30)
==999106== by 0x12E20F: main (main.cc:79)
It seems to me that if the assert doesn't trip, then the object must be
initialized, in which case the switch cannot depend on an uninitialized value.
Many thanks.
--jkl
