[committed][gdb] Fix -Wstrict-null-sentinel warning (--with-iconv-bin)

[Tom de Vries <tdevries at suse dot de>]

[ was: Re: [PATCH 2/2] gdb: Fix a type of sentinel ]

On 30-01-2020 14:58, Lukas Durfina wrote:
> Hello,
> 
> To Simon: I will merge both patches into the single one.

I was not aware of this thread, so I've fixed the gdb_environ::set
occurrence in commit 85f0dd3ce8 "[gdb] Fix -Wstrict-null-sentinel warnings".

After seeing this thread and the charset.c occurrence, I realized it
would cause a build breaker when using --with-iconv-bin, now that we
have the warning on-by-default.

So, given the higher urgency, I've committed the patch for charset.c as
well.

Thanks,
- Tom

[gdb] Fix -Wstrict-null-sentinel warning (--with-iconv-bin)

When using configure flag --with-iconv-bin=$(which iconv), we run into:
...
gdb/charset.c: In function 'void find_charset_names()':
gdb/charset.c:821:75: error: missing sentinel in function call [-Werror=format=]
     iconv_program = concat (iconv_dir.c_str(), SLASH_STRING, "iconv", NULL);
                                                                           ^
cc1plus: all warnings being treated as errors
...

Fix the warning.

Build and reg-tested on x86_64-linux.

2020-02-12  Lukas Durfina  <ldurfina@tachyum.com>
	    Tom de Vries  <tdevries@suse.de>

	* charset.c (find_charset_names): Cast concat NULL sentinel to char *.

---
 gdb/charset.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gdb/charset.c b/gdb/charset.c
index 5cfd2d8030..4e459c2b45 100644
--- a/gdb/charset.c
+++ b/gdb/charset.c
@@ -818,7 +818,8 @@ find_charset_names (void)
   {
     std::string iconv_dir = relocate_gdb_directory (ICONV_BIN,
 						    ICONV_BIN_RELOCATABLE);
-    iconv_program = concat (iconv_dir.c_str(), SLASH_STRING, "iconv", NULL);
+    iconv_program
+      = concat (iconv_dir.c_str(), SLASH_STRING, "iconv", (char *) NULL);
   }
 #else
   iconv_program = xstrdup ("iconv");