[patch, libfortran, committed] Suppress -Wstringop-overflow warning

[Thomas Koenig via Gcc-patches]

Hi,

I just committed as obvious the patch below.

Disable -Wstringop-overflow warning after checking code path of caller.

The warning that is disabled, only on this single line, has been
inspected and found to be not applicable; it is known that the size
of the buffer is safe.

libgfortran/ChangeLog:

2020-06-13  Thomas Koenig  <tkoe...@gcc.gnu.org>

        PR libfortran/95313
        * io/write.c (ztoa_big): Disable -Wstringop-overflow for one
        line.

diff --git a/libgfortran/io/write.c b/libgfortran/io/write.c
index 9f02683a25c..346615ed597 100644
--- a/libgfortran/io/write.c
+++ b/libgfortran/io/write.c
@@ -1178,7 +1178,15 @@ ztoa_big (const char *s, char *buffer, int len, GFC_UINTEGER_LARGEST *n)
 	}
     }
 
+  /* write_z, which calls ztoa_big, is called from transfer.c,
+     formatted_transfer_scalar_write.  There it is passed the kind as
+     argument, which means a maximum of 16.  The buffer is large
+     enough, but the compiler does not know that, so shut up the
+     warning here.  */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
   *q = '\0';
+#pragma GCC diagnostic pop
 
   if (*n == 0)
     return "0";