[Bug c/71803] New: Wpedantic: enumerator value is not an integer constant expression

[johan at forberg dot se]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71803

            Bug ID: 71803
           Summary: Wpedantic: enumerator value is not an integer constant
                    expression
           Product: gcc
           Version: 6.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johan at forberg dot se
  Target Milestone: ---

This concerns GCC 6.1.1 running on Arch Linux amd64. The following code will
produce a warning if compiled with -Wpedantic:

    enum { TEST = 1 << 31 };

The warning is:

    warning: enumerator value for ‘TEST’ is not an integer constant expression
[-Wpedantic]

But if I instead write 

    enum { TEST = 1 << 30 };

There is no warning.

This is unforunate since e.g. the glib/gio headers contain such enums, so they
will add warnings to the compile if using -Wpedantic.

I don't feel that this warning is motivated. According to the C11 standard
(final draft, page 106), an integer constant expression "shall have integer
type and shall only have operands that are integer constants", which by my
understanding this expression satisfies.

Thanks for you attention,
Johan