Re: Warnings in mingw64 builds on master

[Eli Zaretskii]

> From: Andy Moreton <andrewjmoreton@gmail.com>
> Date: Fri, 14 Aug 2020 23:37:27 +0100
> 
> Building master for 64bit mingw64 gives the following warnings:
> 
> C:/emacs/git/emacs/master/src/w32reg.c:146:1: warning: function might be 
> candidate for attribute 'malloc' [-Wsuggest-attribute=malloc]
>   146 | w32_get_string_resource (void *v_rdb, const char *name, const char 
> *class)
>       | ^~~~~~~~~~~~~~~~~~~~~~~

That's just noise.  There's nothing wrong with the code.

> C:/emacs/git/emacs/master/src/w32menu.c: In function 'set_frame_menubar':
> C:/emacs/git/emacs/master/src/w32menu.c:326:2: warning: 'memcpy' offset [3, 
> 10] from the object at '<unknown>' is out of the bounds of referenced 
> subobject 'contents' with type 'union Lisp_X *[]' at offset 3 [-Warray-bounds]
>   326 |  memcpy (previous_items, XVECTOR (f->menu_bar_vector)->contents,
>       |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   327 |   previous_menu_items_used * word_size);
>       |   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> In file included from C:/emacs/git/emacs/master/src/w32menu.c:26:
> C:/emacs/git/emacs/master/src/lisp.h:1631:17: note: subobject 'contents' 
> declared here
>  1631 |     Lisp_Object contents[FLEXIBLE_ARRAY_MEMBER];
>       |                 ^~~~~~~~

Likewise.

> C:/emacs/git/emacs/master/src/w32.c: In function '_sys_read_ahead':
> C:/emacs/git/emacs/master/src/w32.c:8785:10: warning: 'rc' may be used 
> uninitialized in this function [-Wmaybe-uninitialized]
>  8785 |   if (rc == sizeof (char))
>       |       ~~~^~~~~~~~~~~~~~~~

This is a bug in the compiler you are using: rc _is_ initialized.

> C:/emacs/git/emacs/master/src/image.c:116: warning: macro "PIX_MASK_DRAW" is 
> not used [-Wunused-macros]
>   116 | #define PIX_MASK_DRAW 1
>       | 

This macro is used in the PNG code.  Are you building without PNG
support?

> These must have been introduced fairly recently, as the build was clean
> earlier this year.

Actually, this code was not touched in years, so I'm guessing you
upgraded to a later version of the compiler lately.

Thanks.