Large unsigned integer literal is generated to signed literal

[upsuper]

Another issue apart from #272. Having the following code

typedef unsigned long uint32_t;
const uint32_t k = 0x80000000U;

it generates

pub const k: u32 = -2147483648;

which is clearly wrong.

[emilio]

This seems like an overflow happening directly in libclang, that returns an int. I guess we can check if the signedness matches and act properly (either converting, or generating nothing).

I can fix this tomorrow morning if you haven't already :)

[upsuper]

I haven't.

It doesn't seem to me it is easy to check overflow. Probably we should just ignore evaluation from clang and parse integer literals ourselves... But that would make things like 1 << 10 not work, which seems unfortunate as well.

[emilio]

It's not easy to check unfortunately, but we can prevent invalid code easily at least.

[upsuper]

Probably we should also bug libclang to add a better API... but registeration to their bugzilla is closed :/

[emilio]

I have an account and I've sent a few patches already, I should be able to send one for this.

[emilio]

https://reviews.llvm.org/D26788

[upsuper]

Probably makes more sense if it can return a string of the evaluate result, so that it can be extended to whatever length in the future... but probably that's overkill.