The Unicode table code can only be safely called on valid code-points.
So code that calls it must only pass it valid Unicode data. The string
iterator's Unchecked Unchecked methods only provide this guarantee
when the string being iterated is guaranteed to be valid UTF-16; while
client code should only use QString, QStringView and friends on valid
UTF-16 data, we have no way to be sure they have respected that.
So take the few extra cycles to actually check validity in the course
of iterating strings, when the resulting code-points are to be passed
to the Unicode table look-ups. Add tests that case mapping doesn't
access Unicode tables out of range (it'll trigger the new assertion).
Added some comments to qchar.h that helped me understand surrogates.
Change-Id: Iec2c3106bf1a875bdaa1d622f6cf94d7007e281e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
78cf89c07d