Bug fixes
- strictly check operator overload ambiguity (#2762) (dfc8a65)
Operator overload is an internal mechanism, it can support to compare user-defined class, but it need to be limited.
a == b
andb == a
should run the same function and get the same result in semantic level. Allowing ambiguity is bug prone. - report error for mulitple union type (#2872) (1847c8f)