This problem appeared when code was recompiled after upgrading from gcc/gfortran 4.2.4 to 4.3, and was isolated using gcc 4.4.0 on a GNU/Linux Fedora 11 system (32bit intel).
$ gcc -v Using built-in specs. Target: i586-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch=i586 --build=i586-redhat-linux Thread model: posix gcc version 4.4.0 20090506 (Red Hat 4.4.0-4) (GCC) Example fortran program which demonstrates the problem: implicit none integer*4 kmpi integer*2 shortkmpi integer ios character test_file*10 kmpi=12 shortkmpi=kmpi test_file='test.dat' c open and write a test file on unit 12 open(kmpi, file=test_file, status='replace') write(kmpi, *) 1 write(kmpi, *) 2 write(kmpi, *) 3 close(kmpi) write(6,*) 'Try to open and read using integer for unit' open(kmpi, file=test_file, status='old', iostat=ios) if (ios .eq. 0) then write(6,*) ' Successful open using integer unit. ' close(kmpi) else write(6,*) ' Error, failed to open file using integer unit' endif write(6,*) write(6,*) 'Try to open and read using integer*2 for unit' open(shortkmpi, file=test_file, status='old', iostat=ios) if(ios .eq. 0) then write(6,*) ' Successful open using integer*2 unit.' close(shortkmpi) else write(6,*) ' Error, failed to open file using integer*2 unit' endif write(6,*) write(6,*) 'Watch what happens to close() with integer*2 for unit' open(kmpi, file=test_file, status='old', iostat=ios) close(shortkmpi) stop end $ gfortran -Wall -o opentest opentest.f $ opentest Try to open and read using integer for unit Successful open using integer unit. Try to open and read using integer*2 for unit Error, failed to open file using integer*2 unit Watch what happens to close() with integer*2 for unit At line 41 of file opentest.f (unit = 8302168) Fortran runtime error: Unit number in I/O statement too large I then compiled gcc-4.2.4 $ gcc-42 -v Using built-in specs. Target: i686-pc-linux-gnu Configured with: ../gcc-4.2.4/configure --program-suffix=-42 --enable-languages=c,c++,fortran Thread model: posix gcc version 4.2.4 $ gfortran-42 -Wall -o opentest-42 opentest.f $ opentest-42 Try to open and read using integer for unit Successful open using integer unit. Try to open and read using integer*2 for unit Successful open using integer*2 unit. Watch what happens to close() with integer*2 for unit Note that no unit number error occurs here. ---------------------------------------------- The message At line 41 of file opentest.f (unit = 8302168) Fortran runtime error: Unit number in I/O statement too large might suggest that unit numbers stored in integer*2 are being accessed in the fortran io library call as integer*4 ?? I did not find anything in the known bug list or release notes related to this. -- Summary: fortran io unit number specified in a short integer causes open to fail. Product: gcc Version: 4.4.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libfortran AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: yaknai at yahoo dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40652
