In Emacs we have a macro that tends to produce the warning
comparison is always false due to limited range of data type
when compiling for 64-bit machines. EMACS_INT is 64 bits
in that case. Here is the macro:
#define FIXNUM_OVERFLOW_P(i) \
((EMACS_INT)(i) > MOST_POSITIVE_FIXNUM \
|| (
My suggestion is that
(EMACS_INT)(int)(i) > MOST_POSITIVE_FIXNUM
would avoid the warning. But we would not put the casts in the macro
FIXNUM_OVERFLOW_P itself, since that would negate the purpose of the
macro. Instead we would put the cast in the argument, when the
argument is an `int' anyway
I think this warning is starting to happen for valid code because of
64-bit machines.
You can avoid it by using unsigned types. I think that something like
this will do the trick:
#define FIXNUM_OVERFLOW_P(i)\
((unsigned long long)(i) > M
No. This is an undocumented, unnamed, unconditional warning.
We are working on fixing those for GCC 4.3 :-)
Could you explain what that means? What exactly is the problem that
you are talking about fixing? What change is planned?
http://publications.gbdirect.co.uk/c_book/ is reportedly a free
book on C -- but it is C89, more or less.
If it is well written, we could look for people to update it to modern
C. But if it isn't well written and clear, it probably isn't worth
the trouble.
If a few of you who are familiar with o
Nevertheless, I (and others seem to agree) would like to name that
particular warning, so it can be enabled/disabled. Also, there is a
similar warning for unsigned >= 0 and unsigned < 0 in -Wextra. There
are bug reports about the inconsistency (http://gcc.gnu.org/PR23587).
So,
Currently, I believe, GCC combines various calls to abort in a single
function, because it knows that none of them returns.
If the goal is simply to make the compiled code as small as possible,
this is the way to do it. But that is not the best goal when
compiling free software. Merging the vari
Otherwise, we need to consider the merits of disabling an optimization
to make debugging easier.
Optimizing calls to `abort' doesn't offer much benefit, so I think in
this particular case it is worth disabling cross-jumping.
This is a difficult choice to make, but at
-O2, I'd
'abort: core dumped' is not a good user experience. If code is being
shipped with naked aborts in it, that is where the problem lies.
You're entitled to your opinion, but such a conclusion requires much
stronger basis than this.
If
cross jumping makes debugging harder, tough --
The __FILE__ strings will be combined, so you get a most one of it for
each object file.
You're right about that. So the increase in size due to fancy_abort
will be somewhat less than I previously said. However, it will still
be an increase in size, compared with using abort and not
cros
Most people don't do debugging. For some reason you appear to think
that every free software user is also a free software debuggers.
After some 20 years of developing popular free software, I have
somewhat of an idea what users are likely to do. I don't use
fancy_abort functions because
With or without cross-jumping, when the developer gets a
report from a user that "the program died with an abort", he or she has to
debug from scratch, only to find out in many cases that it's a known bug,
already fixed in CVS for the next release, information that would have
> After some 20 years of developing popular free software, I have
> somewhat of an idea what users are likely to do.
Many of us have developed software for a similar period of time,
and yet feel differently.
We may have had different experiences working on different kinds of
progr
> Currently, I believe, GCC combines various calls to abort in a single
> function, because it knows that none of them returns.
afaics it is more generic. It merges them because it knows that it doesn't
make any difference.
Sometimes it is useful to make special exceptions to gene
As I recall, in the old days you (RMS) used to do user polls on occasion.
Would you consider doing it in this case? That is, is it appropriate
for the GNU project to place naked aborts in its programs?
Conducting a poll does not mean asking users to vote on a design
decison or a desig
GCC's primary purpose is to be the compiler for the GNU system. It is
used for many other purposes too, and it is good for GCC to serve more
purposes, but they're not as important for the GNU Project, even
though they are all important for some users.
Meanwhile, assuming that -Os is not implied b
When they see abort: core dumped, they just curse Emacs for losing their
work and switch to vi.
I am dubious of that speculation, because Emacs is very good at not
losing your work.
It's true
that they don't complain about it on the Emacs developer list, where you
participat
petitors which consist of our code plus something
else that is off limits to us.
--
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org www.gnu.org
Skype: No way! That's nonfree (freedom-denying) software.
Use Ekiga or an ordinary phone call.
shed free source code, but under
Apple's rules and Apple's DRM, the binary can't be free.
--
Dr Richard Stallman
President, Free Software Foundation
51 Franklin St
Boston MA 02110
USA
www.fsf.org www.gnu.org
Skype: No way! That's nonfree (freedom-denying) software.
Use Ekiga or an ordinary phone call.
n "System specific".
I will make that change. Thanks.
--
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)
gt; correct: the reference should point to the (cpp) manual instead of the
> (gcc) manual.
What is the full, formal tit;e of the CPP manual? Texinfo cross-references
need to specify that, as well as the short name for Info.
--
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of t
Some macros are predefined on each kind of machine
(@pxref{System specific Predefined Macros, System specific Predefined
Macros, System-specific Predefined Macros, cpp, The C Preprocessor}). This
allows you to provide code specially tuned for a
particular machine.
--
Dr Richard Stallman (
[[[ To any NSA and FBI agents reading my email: please consider]]]
[[[ whether defending the US Constitution against all enemies, ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]
Congratulations on the new release. May it be as boring as we hope.
--
Dr Ri
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