Re: Suspicious warning in W64 build

[Fabrice Popineau <fabrice.popineau@centralesupelec.fr>]

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2017-09-15 11:12 GMT+02:00 Eli Zaretskii <eliz@gnu.org>:

> > From: Fabrice Popineau <fabrice.popineau@centralesupelec.fr>
> > Date: Fri, 15 Sep 2017 08:55:06 +0200
> > Cc: Emacs developers <emacs-devel@gnu.org>
> >
> >  # define pDWP "16llx"
> >  ^
> >
> >  Should these be using the ptrdiff_t formatter pD from lisp.h ?
> >
> > I'd rather cast the values to "long long unsigned int" as these values
> are assumed to be positive,
> > and would be meaningless if printed in decimal.
>
> That's what I did.
>
>
That's ok and no more warnings now.


> > There are also a bunch of warnings in dispnew.c:adjust_glyph_matrix()
> > because the w parameter could be NULL. Actually, some parts of the code
> > are protected with if (w) { ... } but much more than those ones assume
> that
> > w is not NULL.
>
> That's because they really cannot be NULL at that point.  GCC 7
> doesn't really understand the code, so it shouldn't emit these
> warnings, if it wants them to be useful.
>
> > I wonder if the whole function should not just return if w is NULL.
>
> No!


Ok. I see your eassert() added at this point.
But clearly there is a problem with GCC 7, because it doesn't understand
the implications of this eassert() :

  CC       dispnew.o
../../emacs/src/dispnew.c: In function 'adjust_frame_glyphs':
../../emacs/src/dispnew.c:392:14: warning: null pointer dereference
[-Wnull-dereference]
       left = margin_glyphs_to_reserve (w, dim.width, w->left_margin_cols);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:322:11: warning: null pointer dereference
[-Wnull-dereference]
       int width = w->total_cols;
           ^~~~~
../../emacs/src/dispnew.c:393:15: warning: null pointer dereference
[-Wnull-dereference]
       right = margin_glyphs_to_reserve (w, dim.width,
w->right_margin_cols);
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:322:11: warning: null pointer dereference
[-Wnull-dereference]
       int width = w->total_cols;
           ^~~~~
In file included from ../../emacs/src/frame.h:23:0,
                 from ../../emacs/src/dispnew.c:34:
../../emacs/src/window.h:651:38: warning: null pointer dereference
[-Wnull-dereference]
 #define WINDOW_LEFT_PIXEL_EDGE(W) (W)->pixel_left
                                   ~~~^~~
../../emacs/src/dispnew.c:401:36: note: in expansion of macro
'WINDOW_LEFT_PIXEL_EDGE'
    && matrix->window_pixel_left == WINDOW_LEFT_PIXEL_EDGE (w)
                                    ^~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/window.h:660:37: warning: null pointer dereference
[-Wnull-dereference]
 #define WINDOW_TOP_PIXEL_EDGE(W) (W)->pixel_top
                                  ~~~^~~
../../emacs/src/dispnew.c:402:35: note: in expansion of macro
'WINDOW_TOP_PIXEL_EDGE'
    && matrix->window_pixel_top == WINDOW_TOP_PIXEL_EDGE (w)
                                   ^~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:404:34: warning: null pointer dereference
[-Wnull-dereference]
    && matrix->window_vscroll == w->vscroll
                                 ~^~~~~~~~~
../../emacs/src/dispnew.c:392:14: warning: null pointer dereference
[-Wnull-dereference]
       left = margin_glyphs_to_reserve (w, dim.width, w->left_margin_cols);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:322:11: warning: null pointer dereference
[-Wnull-dereference]
       int width = w->total_cols;
           ^~~~~
../../emacs/src/dispnew.c:393:15: warning: null pointer dereference
[-Wnull-dereference]
       right = margin_glyphs_to_reserve (w, dim.width,
w->right_margin_cols);
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:322:11: warning: null pointer dereference
[-Wnull-dereference]
       int width = w->total_cols;
           ^~~~~
In file included from ../../emacs/src/frame.h:23:0,
                 from ../../emacs/src/dispnew.c:34:
../../emacs/src/window.h:651:38: warning: null pointer dereference
[-Wnull-dereference]
 #define WINDOW_LEFT_PIXEL_EDGE(W) (W)->pixel_left
                                   ~~~^~~
../../emacs/src/dispnew.c:401:36: note: in expansion of macro
'WINDOW_LEFT_PIXEL_EDGE'
    && matrix->window_pixel_left == WINDOW_LEFT_PIXEL_EDGE (w)
                                    ^~~~~~~~~~~~~~~~~~~~~~
../../emacs/src/window.h:660:37: warning: null pointer dereference
[-Wnull-dereference]
 #define WINDOW_TOP_PIXEL_EDGE(W) (W)->pixel_top
                                  ~~~^~~
../../emacs/src/dispnew.c:402:35: note: in expansion of macro
'WINDOW_TOP_PIXEL_EDGE'
    && matrix->window_pixel_top == WINDOW_TOP_PIXEL_EDGE (w)
                                   ^~~~~~~~~~~~~~~~~~~~~
../../emacs/src/dispnew.c:404:34: warning: null pointer dereference
[-Wnull-dereference]
    && matrix->window_vscroll == w->vscroll
                                 ~^~~~~~~~~
cc1.exe: warning: null pointer dereference [-Wnull-dereference]
cc1.exe: warning: null pointer dereference [-Wnull-dereference]

-- 
Fabrice

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