[Bug sanitizer/80404] New: UBSAN: compile time crash with "non-trivial conversion at assignment" error

["babokin at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80404

            Bug ID: 80404
           Summary: UBSAN: compile time crash with "non-trivial conversion
                    at assignment" error
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: babokin 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: ---

gcc x86_64, top of the trunk.

> cat f.cpp
extern short var_54;
unsigned foo() {
  unsigned a = (0 < 0 >= (0 >= 0)) / unsigned(var_54);
  return a;
}

> g++ -fsanitize=undefined -w -O0 -c f.cpp
f.cpp: In function ‘unsigned int foo()’:
f.cpp:2:10: error: non-trivial conversion at assignment
 unsigned foo() {
          ^~~
unsigned int
int
a = 0;
f.cpp:2:10: internal compiler error: verify_gimple failed
<...>