Re: groff 1.23.0.rc4 on Solaris 10

[Bruno Haible]

On Solaris 10, I tried two compilers, like last time
(see https://lists.gnu.org/archive/html/groff/2023-03/msg00005.html):

* The Sun C, C++ compilers.

  The build failure regarding <stdbool.h> is gone.

  Now there is a build failure:

  CC       src/libs/libgroff/libgroff_a-getopt.o
"../src/libs/libgroff/getopt.c", line 251: syntax error before or at: (
"../src/libs/libgroff/getopt.c", line 252: syntax error before or at: (
"../src/libs/libgroff/getopt.c", line 253: syntax error before or at: const
"../src/libs/libgroff/getopt.c", line 253: syntax error before or at: int
"../src/libs/libgroff/getopt.c", line 254: syntax error before or at: struct
"../src/libs/libgroff/getopt.c", line 254: syntax error before or at: )
"../src/libs/libgroff/getopt.c", line 273: zero or negative subscript
"../src/libs/libgroff/getopt.c", line 273: syntax error before or at: ==
"../src/libs/libgroff/getopt.c", line 278: warning: old-style declaration or 
incorrect type for: __posixly_correct
"../src/libs/libgroff/getopt.c", line 279: warning: old-style declaration or 
incorrect type for: d
...

  The cause is apparently the use of __attribute__((__unused__))
  in src/libs/libgroff/getopt.c line 251.

  This syntax is not portable; it works only in GCC, clang, and AIX xlc.

  Instead, you can use the Gnulib module 'attribute', #include "attribute.h",
  and use MAYBE_UNUSED instead of __attribute__((__unused__)). This is portable.

* The gcc, g++ compilers.

  Now 152 instead of 150 test failures.

Bruno