[patch, libgfortran] PR117820

[Jerry D]

Hi all,

Attached patch adds a test for zero that is needed for write_boz to work 
correctly. Almost obvious.

Regression tested on x86_64.

Ok for trunk?

Jerry

Author: Jerry DeLisle <jvdeli...@gcc.gnu.org>
Date:   Mon Dec 2 19:45:26 2024 -0800

    Fortran: Fix B64.0 formatted write output.

            PR fortran/117820

    libgfortran/ChangeLog:

            * io/write.c (write_b): Add test for zero needed by write_boz.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/pr117820.f90: New test.

diff --git a/gcc/testsuite/gfortran.dg/pr117820.f90 b/gcc/testsuite/gfortran.dg/pr117820.f90
new file mode 100644
index 00000000000..e873393f2ef
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr117820.f90
@@ -0,0 +1,12 @@
+! { dg-do run }
+! { dg-options "-std=gnu" }
+! see pr117820, -std=gnu for this test needed to avoid a warning with -pedantic
+! on line 9 below.
+program test
+  integer(8) :: x
+  character(80) :: output
+  output = "garbage"
+  x = -huge(x) - 1_8
+  write(output, '("<",B64.0,">")') x
+  if (output .ne. "<1000000000000000000000000000000000000000000000000000000000000000>") stop 1
+end program
diff --git a/libgfortran/io/write.c b/libgfortran/io/write.c
index 2f414c6b57d..ccb2b5cb810 100644
--- a/libgfortran/io/write.c
+++ b/libgfortran/io/write.c
@@ -1392,6 +1392,10 @@ write_b (st_parameter_dt *dtp, const fnode *f, const char *source, int len)
     {
       n = extract_uint (source, len);
       p = btoa (n, itoa_buf, sizeof (itoa_buf));
+
+      /* Test for zero. Needed by write_boz.  */
+      if (n != 0)
+       n = 1;
       write_boz (dtp, f, p, n, len);
     }
 }