[Bug c/60083] Duplicate conversion warnings from negative integer to unsigned type (gcc-4.3 emits only one warning)

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60083

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r139049.