Rearchitect -Wconversion and -Wsign-compare. Instead of computing them
"bottom-up" when implicit casts and comparisons are inserted, compute them
"top-down" when the full expression is finished. Makes it easier to
coordinate warnings and thus implement -Wconversion for signedness
conversions without double-warning with -Wsign-compare. Also makes it possible
to realize that a signedness conversion is okay because the context is
performing the inverse conversion. Also simplifies some logic that was
trying to calculate the ultimate comparison/result type and getting it wrong.
Also fixes a problem with the C++ explicit casts which are often "implemented"
in the AST with a series of implicit cast expressions.
llvm-svn: 103174
11 files changed