Re: warnings compiling Emacs 22 on amd64

[Stefan Monnier]

>> But since this warning is about something which is not itself a bug, either
>> gcc provides a way to annotate the code to indicate that this is not a bug
>> (like the use of double-parens to turn off the warning about assignment in
>> an `if'), or there's not much we can do about it (other than try to work
>> around it by making the code ugly, less robust, and maybe even less
>> efficient: after all the warning here is output specifically when gcc finds
>> an optimization).

> First I tried to work around it by making the code slightly more
> complex, but still clear.  However, I failed.

> I looked at the gcc 4.1 info page, and I found no warnings to turn off
> that are specific for this case (I looked for the string "compar").

Yes, I believe there's no way.  Which is why I think the least bad course
is -Wno-foo.

> As far as code annotations are concerned, I don't know where to look: I
> had never heard of the double parenthesis trick, nor was I able to find
> it in the gcc info page.

Can't remember where I saw it, but if you do

      if (foo = bar) ...

gcc warns that you may have meant == instead of =, so if you really meant =
you can just write

      if ((foo = bar)) ...

and gcc will then keep quiet.


        Stefan