commit c14f38d4292ec22462a4080841d526f87428130a
Author: Francois-Xavier Coudert <fxcoudert@gcc.gnu.org>
Date:   Thu Dec 16 15:33:17 2021 +0100

    Fix FLUSH IOSTAT value
    
    PR libfortran/101255
    
    libgfortran/ChangeLog:
    
            * io/file_pos.c: Fix error code.
    
    gcc/testsuite/ChangeLog:
    
            * gfortran.dg/iostat_5.f90: New file.

diff --git a/gcc/testsuite/gfortran.dg/iostat_5.f90 b/gcc/testsuite/gfortran.dg/iostat_5.f90
new file mode 100644
index 00000000000..1e72dfdf7e1
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/iostat_5.f90
@@ -0,0 +1,16 @@
+! PR libfortran/101255
+! { dg-do run }
+
+program test
+  use ISO_FORTRAN_ENV, only: IOSTAT_EOR, IOSTAT_END
+  implicit none
+  character(len=50) :: err
+  integer :: i
+
+  err = ""
+  flush(99, iostat=i, iomsg=err)
+
+  if (err == "") stop 1
+  if (i >= 0) stop 2
+  if (i == IOSTAT_EOR .or. i == IOSTAT_END) stop 3
+end
diff --git a/libgfortran/io/file_pos.c b/libgfortran/io/file_pos.c
index 7e71ca577e0..4ed1698f17a 100644
--- a/libgfortran/io/file_pos.c
+++ b/libgfortran/io/file_pos.c
@@ -527,7 +527,7 @@ st_flush (st_parameter_filepos *fpp)
     }
   else
     /* FLUSH on unconnected unit is illegal: F95 std., 9.3.5. */ 
-    generate_error (&fpp->common, LIBERROR_BAD_OPTION,
+    generate_error (&fpp->common, -LIBERROR_BAD_UNIT,
 			"Specified UNIT in FLUSH is not connected");
 
   if (needs_unlock)