[Bug other/122729] New: Including libiberty.h triggers -Wundef warning ("HAVE_DECL_BASENAME" conditional)

[Explorer09 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122729

            Bug ID: 122729
           Summary: Including libiberty.h triggers -Wundef warning
                    ("HAVE_DECL_BASENAME" conditional)
           Product: gcc
           Version: 15.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Explorer09 at gmail dot com
  Target Milestone: ---

The error message is:

```
/usr/include/libiberty/libiberty.h:107:6: error: "HAVE_DECL_BASENAME" is not
defined, evaluates to 0 [-Werror=undef]
  107 | #if !HAVE_DECL_BASENAME
      |      ^~~~~~~~~~~~~~~~~~
```

It seems like the conditional can be changed from:

```
#if !HAVE_DECL_BASENAME
```

to:

```
#if !defined(HAVE_DECL_BASENAME) || !HAVE_DECL_BASENAME
```

and the problem can go away.