swift234

Sema: Check that enum raw values are unique.

Track raw values of the enum in a DenseMap and flag repeat values, taking care to treat equal floating-point and integer values as the same key. Also keep track of the most recent explicit raw value for each implicit raw value, so that if we end up with repeated values due to auto-incrementing behavior, the diagnostic can include notes about where the auto-increment began.

Swift SVN r8586