[Bug libfortran/63471] New: [5.0 Regression] unix.c:1906:10: error: implicit declaration of function 'ttyname_r'

["danglin at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63471

            Bug ID: 63471
           Summary: [5.0 Regression] unix.c:1906:10: error: implicit
                    declaration of function 'ttyname_r'
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libfortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: danglin at gcc dot gnu.org
              Host: hppa64-hp-hpux11.11
            Target: hppa64-hp-hpux11.11
             Build: hppa64-hp-hpux11.11

libtool: compile:  /test/gnu/gcc/objdir/./gcc/xgcc
-B/test/gnu/gcc/objdir/./gcc/
 -B/opt/gnu64/gcc/gcc-5.0/hppa64-hp-hpux11.11/bin/
-B/opt/gnu64/gcc/gcc-5.0/hppa
64-hp-hpux11.11/lib/ -isystem
/opt/gnu64/gcc/gcc-5.0/hppa64-hp-hpux11.11/include
 -isystem /opt/gnu64/gcc/gcc-5.0/hppa64-hp-hpux11.11/sys-include
-DHAVE_CONFIG_H
 -I. -I../../../gcc/libgfortran -iquote../../../gcc/libgfortran/io
-I../../../gc
c/libgfortran/../gcc -I../../../gcc/libgfortran/../gcc/config
-I../../../gcc/lib
gfortran/../libquadmath -I../.././gcc -I../../../gcc/libgfortran/../libgcc
-I../libgcc -std=gnu11 -Wall -Wstrict-prototypes -Wmissing-prototypes
-Wold-style-definition -Wextra -Wwrite-strings
-Werror=implicit-function-declaration -fcx-fortran-rules -ffunction-sections
-fdata-sections -g -O2 -MT unix.lo -MD -MP -MF .deps/unix.Tpo -c
../../../gcc/libgfortran/io/unix.c  -DPIC -o .libs/unix.o
../../../gcc/libgfortran/io/unix.c: In function 'stream_ttyname':
../../../gcc/libgfortran/io/unix.c:1906:10: error: implicit declaration of
function 'ttyname_r' [-Werror=implicit-function-declaration]
   return ttyname_r (((unix_stream *) s)->fd, buf, buflen);
          ^
cc1: some warnings being treated as errors
make[3]: *** [unix.lo] Error 1

Probably _REENTRANT is not defined.