[Bug c++/71472] New: Wlogical-op misses exhaustive-or case (... || A) || B

[terra at gnome dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71472

            Bug ID: 71472
           Summary: Wlogical-op misses exhaustive-or case (... || A) || B
           Product: gcc
           Version: 6.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: terra at gnome dot org
  Target Milestone: ---

g++ 6.1 fails to complain about "bar" below.  The other two get the
expected "logical 'or' of collectively exhaustive tests is always true"
warning.


enum Enum { ENUM_A, ENUM_B, ENUM_C };

int
foo (enum Enum e)
{
  // This produces a warning
  return e != ENUM_A || e != ENUM_B;
}

int
bar (int i, enum Enum e)
{
  // This does not produce a warning
  return i != 42 || e != ENUM_A || e != ENUM_B;
}

int
baz (int i, enum Enum e)
{
  // This produces a warning
  return e != ENUM_A || e != ENUM_B || i != 42;
}