Out of range integers silently accepted

[amerry]

If an integer constant that is too large or small to fit in an int64_t is specified in the toml file, it will be silently accepted and INT64_MAX or INT64_MIN will be set instead. There appears to be no way for code using toml11 to detect this (and, eg, report to the user that this will not have the expected behaviour).

Steps to reproduce

std::istringstream ss{"int_value = 9223372036854775808"};
auto const value = toml::parse(ss);
assert(value.as_table().at("int_value").as_integer() == 9223372036854775807);

Expected behaviour

toml::parse throws an exception (or maybe the problem is reported directly on the integer toml::value?).

Actual behaviour

toml::parse succeeds, and the assert passes.

[ToruNiina]

Okay, this is a bug. Thank you for reporting.

I have investigated a bit and found that

• toml::detail::parse_integer uses istringstream >> toml::integer
• stream operator calls std::num_get::get
• std::num_get::get calls std::strtoll
• std::strtoll returns LONG_MAX if the converted value falls out of range and sets errno = ERANGE.
• if std::strtoll fails, failbit is set. And errno seems to be cleared.

This can be fixed by checking failbit in parse_integer. I think the same happens in parse_floating too. I will check and fix it too.

[amerry]

NB: I didn't check what happens with hex or binary integers, which seem to use a different code path to decimal integers.

[ToruNiina]

Now it throws an error and I added a test to check if an error is thrown when too large value is given. Thanks again!