This new checker tries to find execution paths on which implicit integral casts
cause definite loss of information: a certainly-negative integer is converted
to an unsigned integer, or an integer is definitely truncated to fit into
a smaller type.
Being implicit, such casts are likely to produce unexpected results.
Patch by Daniel Marjamäki!
Differential Revision: https://reviews.llvm.org/D13126
llvm-svn: 278941