Re: say which of .PRECIOUS: %.o *.o file.o will actually work

[Dmitry Goncharov]

On Thursday, October 10, 2024, Britton Kerin <britton.kerin@gmail.com> wrote:
> On Wed, Oct 9, 2024 at 4:01 PM Dmitry Goncharov <dgoncharov@users.sf.net> wrote:
>>
>> On Tue, Oct 8, 2024 at 11:16 PM Dan Jacobson <jidanni@jidanni.org> wrote:
>> >
>> > Manual says:
>> >
>> >    You can list the target pattern of an implicit rule (such as '%.o')
>> >    as a prerequisite of the special target '.PRECIOUS' to preserve
>> >    intermediate files made by implicit rules whose target patterns match
>> >    that file's name; see *note Interrupts::.
>> >
>> > Well say which of
>> > .PRECIOUS: %.o
>> > .PRECIOUS: *.o
>> > .PRECIOUS: file.o
>> > will actually work.
>> >
>> > The words above make the reader think they should use the first form.
>> >
>> > But in my experiments, only this last one works.
>>
>> .PRECIOUS: %.o has the desired effect when a related implicit rule is used.
>> For example, the following marks hello.x and hello.q as precious.
>>
>> .PRECIOUS: %.x %.q
>> all: hello.x
>> %.x: %.q; $(info $@ from $<)
>> %.q:;
>
> Does this work for static patterns also?


Use of patterns to mark files precious has effect only if a related implicit rule is used.
There is little benefit to mark files built by static pattern rules precious,  because static pattern rules do not build intermediate files.

Regards,Dmitry