<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/128609>128609</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Flang] The value of c_intmax_t defined in iso_c_binding is different for Flang and Gfortran/ifx.
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            flang
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          ohno-fj
      </td>
    </tr>
</table>

<pre>
    ```
Version of flang : 21.0.0(f75126eeabba13ce2aab53c2e4296fca12b9da0d)/AArch64
```

While running the attached program, I noticed that the value of `c_intmax_t` defined in `iso_c_binding` is different for Flang and Gfortran/ifx.  
Flang is 16 and Gfortran/ifx is 8.  
```
$ grep c_intmax_t /work/groups/ssoft/compiler/llvm/aarch64/main-latest/include/flang/iso_c_binding.mod 
integer(4),parameter::c_intmax_t=16_4
$
```
Is there no problem that the value of flang is different from the value of gfortran/ifx?

The following are the test program, Flang, Gfortran and ifx compilation/execution result.

snfg1101_err077_2.f90:
```fortran
program main
  use , intrinsic :: iso_c_binding
  call csub1()
contains
  subroutine csub1()
 logical(c_intmax_t)        :: i_c_intmax_t
    i_c_intmax_t = .TRUE.
 print *,i_c_intmax_t
    print *,c_sizeof(i_c_intmax_t)
  end subroutine csub1
end program main
```

```
$ flang snfg1101_err077_2.f90
error: Semantic errors in snfg1101_err077_2.f90
./snfg1101_err077_2.f90:6:5: error: LOGICAL(KIND=16) is not a supported type
      logical(c_intmax_t)        :: i_c_intmax_t
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
$ 
```

```
$ gfortran snfg1101_err077_2.f90; ./a.out
snfg1101_err077_2.f90:6:11:

    6 |     logical(c_intmax_t) :: i_c_intmax_t
      |           1
Warning: C kind type parameter is for type INTEGER but type at (1) is LOGICAL
 T
                    8
$ 
```

```
$ ifx snfg1101_err077_2.f90; ./a.out
 T
 8
$ 
```

</pre>
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