[PATCH] toplev.c: Check for null argument to fprintf

[Stefan Schulze Frielinghaus via Gcc-patches]

Ensure that CF does not equal NULL in function output_stack_usage_1
before calling fprintf.  This fixes the following warning/error:

gcc/toplev.c:976:13: error: argument 1 null where non-null expected 
[-Werror=nonnull]
  976 |     fprintf (cf, "\\n" HOST_WIDE_INT_PRINT_DEC " bytes (%s)",
      |     ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  977 |       stack_usage,
      |       ~~~~~~~~~~~~
  978 |       stack_usage_kind_str[stack_usage_kind]);

An example call side where CF is NULL is in function output_stack_usage.

Bootstrapped and regtested successfully on S/390. Ok for master?

gcc/ChangeLog:

2020-04-28  Stefan Schulze Frielinghaus  <stefa...@linux.ibm.com>

        * toplev.c (output_stack_usage_1): Ensure that first
        argument to fprintf is not null.
---
 gcc/toplev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/toplev.c b/gcc/toplev.c
index 4c8be502c71..5c026feece2 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -972,7 +972,7 @@ output_stack_usage_1 (FILE *cf)
       stack_usage += current_function_dynamic_stack_size;
     }
 
-  if (flag_callgraph_info & CALLGRAPH_INFO_STACK_USAGE)
+  if (cf && flag_callgraph_info & CALLGRAPH_INFO_STACK_USAGE)
     fprintf (cf, "\\n" HOST_WIDE_INT_PRINT_DEC " bytes (%s)",
             stack_usage,
             stack_usage_kind_str[stack_usage_kind]);
-- 
2.25.3