Re: [PULL 04/16] curses: Fixes curses compiling errors.

["罗勇刚(Yonggang Luo)" <luoyonggang@gmail.com>]

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On Wed, Sep 9, 2020 at 4:29 AM Peter Maydell <peter.maydell@linaro.org>
wrote:

> On Tue, 8 Sep 2020 at 19:56, Yonggang Luo <luoyonggang@gmail.com> wrote:
> >
> > This is the compiling error:
> > ../ui/curses.c: In function 'curses_refresh':
> > ../ui/curses.c:256:5: error: 'next_maybe_keycode' may be used
> uninitialized in this function [-Werror=maybe-uninitialized]
> >   256 |     curses2foo(_curses2keycode, _curseskey2keycode, chr,
> maybe_keycode)
> >       |     ^~~~~~~~~~
> > ../ui/curses.c:302:32: note: 'next_maybe_keycode' was declared here
> >   302 |             enum maybe_keycode next_maybe_keycode;
> >       |                                ^~~~~~~~~~~~~~~~~~
> > ../ui/curses.c:256:5: error: 'maybe_keycode' may be used uninitialized
> in this function [-Werror=maybe-uninitialized]
> >   256 |     curses2foo(_curses2keycode, _curseskey2keycode, chr,
> maybe_keycode)
> >       |     ^~~~~~~~~~
> > ../ui/curses.c:265:24: note: 'maybe_keycode' was declared here
> >   265 |     enum maybe_keycode maybe_keycode;
> >       |                        ^~~~~~~~~~~~~
> > cc1.exe: all warnings being treated as errors
>
> > Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
> > ---
> >  ui/curses.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/ui/curses.c b/ui/curses.c
> > index 12bc682cf9..e4f9588c3e 100644
> > --- a/ui/curses.c
> > +++ b/ui/curses.c
> > @@ -262,7 +262,7 @@ static int curses2foo(const int _curses2foo[], const
> int _curseskey2foo[],
> >  static void curses_refresh(DisplayChangeListener *dcl)
> >  {
> >      int chr, keysym, keycode, keycode_alt;
> > -    enum maybe_keycode maybe_keycode;
> > +    enum maybe_keycode maybe_keycode = CURSES_KEYCODE;
> >
> >      curses_winch_check();
> >
> > @@ -299,7 +299,7 @@ static void curses_refresh(DisplayChangeListener
> *dcl)
> >
> >          /* alt or esc key */
> >          if (keycode == 1) {
> > -            enum maybe_keycode next_maybe_keycode;
> > +            enum maybe_keycode next_maybe_keycode = CURSES_KEYCODE;
> >              int nextchr = console_getch(&next_maybe_keycode);
> >
> >              if (nextchr != -1) {
>
> The problem here is that the compiler hasn't noticed that it's
> impossible to return something other than -1 from console_getch()
> without initializing next_maybe_keycode.
>
> There are two possible reasons for this:
> (1) your gcc is a bit old -- newer gcc are better at working
> out this kind of thing. But you said on irc that you're using
> gcc 10.2.0, which is new...
>
> (2) this is a variant of the problem with the system headers
> that causes us to have to redefine assert() in osdep.h, only
> with abort() (ie abort() is perhaps not marked as noreturn in
> the system headers). If this theory is true, then changing
> the abort() in console_getch() to instead be g_assert_not_reached()
> would be a different way to avoid the warnings (and if that works
> we should probably fix up abort() the way we do assert()).
>
Tried   g_assert_not_reached still not fixes the issue, and I verified
on debug build, either g_assert_not_reached or abort, the compiling error
doesn't appear,
the debug build are the build that configured with --enable-debug-info
--enable-debug

this compiling error only appear in release build.

>
> thanks
> -- PMM
>


-- 
         此致
礼
罗勇刚
Yours
    sincerely,
Yonggang Luo

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