Re: New warning

[Eshel Yaron]

Po Lu <luangruo@yahoo.com> writes:

> Since a previous commit, I get:
>
> ../../emacs/src/window.c: In function ‘window_wants_header_line’:
> ../../emacs/src/window.c:5546:19: warning: potential null pointer dereference 
> [-Wnull-dereference]
>  5546 |               || !null_header_line_format (BVAR (XBUFFER 
> (WINDOW_BUFFER (w)),
>       |                   
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>  5547 |                                                  header_line_format), 
> f))
>       |                                                  
> ~~~~~~~~~~~~~~~~~~~~~~~
>
> Would someone please look into this?
> Thanks.

Hmm, clang doesn't emit this warning (and I didn't try compiling with
gcc before submitting that patch, sorry about that).

The following seems to silence this warning with gcc 13.1, but I'm not
sure I fully understand why/when WINDOW_BUFFER might return NULL, so I'm
not sure it's the right thing to do... Any insights?

diff --git a/src/window.c b/src/window.c
index 81578375498..644fcab9d04 100644
--- a/src/window.c
+++ b/src/window.c
@@ -5540,6 +5540,7 @@ window_wants_header_line (struct window *w)
          && !WINDOW_PSEUDO_P (w)
          && !EQ (window_header_line_format, Qnone)
          && (!null_header_line_format (window_header_line_format, f)
+             || !WINDOW_BUFFER (w)
              || !null_header_line_format (BVAR (XBUFFER (WINDOW_BUFFER (w)),
                                                 header_line_format), f))
          && (WINDOW_PIXEL_HEIGHT (w)