bitwise operators dont have desired results when compiled to javascript

[adam-singer]

dart2js does not carry the signed bit when code is compiled to javascript that uses the shift operators << >> . This leads to bugs with the way bit shifting is implemented with native dart int.

[ltackmann]

Are these bugs contained to shifting operations on BigNum or are they also apparent when doing ordinary math with bignums (which also internally rely on shifting) ?

[adam-singer]

I think its only when shifting numbers that are negative the object fails. Internally none of numbers in the internal data structure should be negative, so all computations should be safe. I noticed this issue when dealing with negative numbers and put a safe guard in for checking a shift on negative carry http://goo.gl/Ayjnv . While I dont like this solution at the moment, it seems to work.

[adam-singer]

google group discussion started on this https://groups.google.com/a/dartlang.org/d/topic/misc/3olrB-Fkd5U/discussion