[Flang] cannot use real_kinds(i) in program

[k-arrows]

The following test1.f90 works but test2.f90 does not.

$ cat test1.f90
program test1
    use iso_fortran_env
    print *, size(real_kinds)
    print *, real_kinds(1)
    print *, real_kinds(2)
    print *, real_kinds(3)
    print *, real_kinds(4)
    print *, real_kinds(5)
    print *, real_kinds(6)
end program test1
$ flang-new test1.f90
$ ./a.out
 6
 2
 3
 4
 8
 10
 16

$ cat test2.f90
program test2
    use iso_fortran_env
    integer :: i
    do i = 1, size(real_kinds)
        print *, real_kinds(i)
    end do
end program test2
$ flang-new test2.f90
/usr/bin/ld: /tmp/test2-05b748.o: in function `_QQmain':
FIRModule:(.text+0x63): undefined reference to `_QMiso_fortran_envECreal_kinds'
flang-new: error: linker command failed with exit code 1 (use -v to see invocation)

It seems to be a linker issue, so it may be a problem specific to my environment. If so, please close this issue. But in my environment test2.f90 works if I use gfortran.

$ gfortran test2.f90
$ ./a.out
           4
           8
          10
          16

[hym3242]

Maybe you should also post linker command invocation with -v

[brtnfld]

It also fails in the same manner for integer_kinds and logical_kinds. This causes HDF5 fail to be configured, as we use this test program if ISO_FORTRAN_ENV is available.

PROGRAM FC08_AVAIL_KINDS
       USE, INTRINSIC :: ISO_FORTRAN_ENV, ONLY : stdout=>OUTPUT_UNIT, integer_kinds, real_kinds, logical_kinds
       IMPLICIT NONE
       INTEGER :: ik, jk, k, max_decimal_prec
       INTEGER :: num_rkinds, num_ikinds, num_lkinds
 
       num_ikinds = SIZE(integer_kinds)

       DO k = 1, num_ikinds
          PRINT*, integer_kinds(k)
       ENDDO

 END PROGRAM FC08_AVAIL_KINDS

flang-new version 19.0.0git (https://github.com/llvm/llvm-project.git a4de589)
Target: x86_64-unknown-linux-gnu
Thread model: posix
Found candidate GCC installation: /usr/lib64/gcc/x86_64-suse-linux/12
Found candidate GCC installation: /usr/lib64/gcc/x86_64-suse-linux/13
Found candidate GCC installation: /usr/lib64/gcc/x86_64-suse-linux/7
Selected GCC installation: /usr/lib64/gcc/x86_64-suse-linux/13
Candidate multilib: .;@m64
Selected multilib: .;@m64
"packages/llvm-project/build/bin/flang-new" -fc1 -triple x86_64-unknown-linux-gnu -emit-obj -fcolor-diagnostics -mrelocation-model pic -pic-level 2 -pic-is-pie -target-cpu x86-64 -mframe-pointer=all -o /tmp/test-72928d.o -x f95-cpp-input test.F90
"/usr/lib64/gcc/x86_64-suse-linux/13/../../../../x86_64-suse-linux/bin/ld" --hash-style=gnu --eh-frame-hdr -m elf_x86_64 -pie -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o a.out /usr/lib64/gcc/x86_64-suse-linux/13/../../../../lib64/Scrt1.o /usr/lib64/gcc/x86_64-suse-linux/13/../../../../lib64/crti.o /usr/lib64/gcc/x86_64-suse-linux/13/crtbeginS.o -L/usr/lib64/gcc/x86_64-suse-linux/13 -L/usr/lib64/gcc/x86_64-suse-linux/13/../../../../lib64 -L/lib/../lib64 -L/usr/lib/../lib64 -L/usr/lib64/gcc/x86_64-suse-linux/13/../../../../x86_64-suse-linux/lib -L/lib -L/usr/lib -L/home/brtnfld/packages/aocc-compiler-4.2.0/lib -L/home/brtnfld/packages/aocc-compiler-4.2.0/lib32 -L/usr/lib64 -L/usr/lib -L/home/brtnfld/packages/aocc-compiler-4.2.0/lib -L/home/brtnfld/packages/aocc-compiler-4.2.0/lib32 -L/usr/lib64 -L/usr/lib -L. /tmp/test-72928d.o -L/home/brtnfld/packages/llvm-project/build/lib --whole-archive -lFortran_main --no-whole-archive -lFortranRuntime -lFortranDecimal -lm -lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s --no-as-needed /usr/lib64/gcc/x86_64-suse-linux/13/crtendS.o /usr/lib64/gcc/x86_64-suse-linux/13/../../../../lib64/crtn.o
/usr/lib64/gcc/x86_64-suse-linux/13/../../../../x86_64-suse-linux/bin/ld: /tmp/test-72928d.o: in function _QQmain': FIRModule:(.text+0x69): undefined reference to _QMiso_fortran_envECinteger_kinds'
flang-new: error: linker command failed with exit code 1 (use -v to see invocation)

[hakostra]

This issue seems to be fixed:

$ flang-new flang-issue-77282.f90 
$ ./a.out 
 2
 3
 4
 8
 10
 16

integer_kinds print:

$ ./a.out 
 1
 2
 4
 8
 16

Tested with:

$ flang-new --version
flang-new version 20.0.0git (https://github.com/llvm/llvm-project.git 6c607cfb2c2d8acd2b92d7ed8106ab1e4fc0d79d)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/llvm/llvm-project/install/bin