[Bug sanitizer/118972] New: Missing ubsan complaint for double->int cast overflow

[blubban at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118972

            Bug ID: 118972
           Summary: Missing ubsan complaint for double->int cast overflow
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: blubban at gmail dot com
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
  Target Milestone: ---

int main()
{
    double max = __DBL_MAX__;
    __builtin_printf("%x\n", (int)(double)max);
    __builtin_printf("%x\n", (int)(double)__DBL_MAX__);
}

-O0 -fsanitize=undefined -Wall -Wextra


Expected: Two UBSan complaints or compiler warnings. Or, if GCC defines some
particular semantics for overflowing double->int casts, at least return the
same number for both.

Actual:

80000000
7fffffff

Clang's UBSan complains about both, as expected (then returns different
numbers, but that's fine, it's UB). https://godbolt.org/z/8rK7co19s