Обсуждение: makefiles writing to $@ should first write to $@.new
There are many Makefile rules like
foo: bar
./tool $< > $@
If the rule is interrupted (due to ^C or ENOSPC), foo can be 0 bytes or
partially written, but won't be rebuilt until someone runs distclean or debugs
it and removes the individual file, as I did for errcodes.h.
It'd be better if these did
./tool $< > $@.new
mv $@.new $@
--
Justin
On Sun, Jan 23, 2022 at 09:23:05PM -0600, Justin Pryzby wrote: > If the rule is interrupted (due to ^C or ENOSPC), foo can be 0 bytes or > partially written, but won't be rebuilt until someone runs distclean or debugs > it and removes the individual file, as I did for errcodes.h. Honestly, I am not sure that this worth bothering about. This comes down to a balance between the code complexity and the likelihood of a failure, and the odds are not in favor of the later IMO. Now, it could be perhaps possible to make such a change simple enough while it avoids a lot of technical debt, but we have a lot of custom rules particularly in src/bin/, so changing all that or even require that in future changes is not really appealing. -- Michael
Вложения
Julien Rouhaud <rjuju123@gmail.com> writes:
> On Mon, Jan 24, 2022 at 12:41:49PM +0900, Michael Paquier wrote:
>> Honestly, I am not sure that this worth bothering about. This comes
>> down to a balance between the code complexity and the likelihood of a
>> failure, and the odds are not in favor of the later IMO. Now, it
>> could be perhaps possible to make such a change simple enough while it
>> avoids a lot of technical debt, but we have a lot of custom rules
>> particularly in src/bin/, so changing all that or even require that in
>> future changes is not really appealing.
> I agree, it doesn't seem worth it.
Agreed. Another reason to not bother about this is the likelihood
that it'd all be wasted effort as soon as we switch to meson.
If that project fails, I'd be open to revisiting this issue;
but I don't think we should spend time improving the Makefiles
right now.
regards, tom lane
On 24.01.22 04:23, Justin Pryzby wrote: > There are many Makefile rules like > > foo: bar > ./tool $< > $@ > > If the rule is interrupted (due to ^C or ENOSPC), foo can be 0 bytes or > partially written, but won't be rebuilt until someone runs distclean or debugs > it and removes the individual file, as I did for errcodes.h. If a rule fails, make removes the target file. So I don't see how this can happen unless you hard kill -9 make or something like that.