Re: Parallel problem

[Tomas Nordin]

Paul Smith <psmith@gnu.org> writes:

> On Tue, 2021-01-12 at 12:35 +0000, jeremiah@pdp10.guru wrote:
>> > After a quick squiz at your makefile I’m guessing line 42 should
>> > not read
>> >         -o bin/M2-Planet
>> > But rather
>> >         -o M2-Planet
>> > Or even better:
>> >         -o $@
>> > No?
>> > Similar changes for line 67 are probably in order
>> 
>> No that does not correct the issue reported.
>> As bin is in the VPATH on line 19.
>
> Whether bin is on VPATH is not relevant.  That's not how VPATH works:
> VPATH is _only_ useful for locating _source_ files (files that always
> exist).  It cannot be used for locating generated files.
>
> For more details read this:
>
> http://make.mad-scientist.net/papers/how-not-to-use-vpath/
>
>> Further it would break the all of the tests.
>> As they expect bin/M2-Planet.
>
> Your rule MUST ALWAYS build the target file that you told make they
> would build.  It's invalid, and will lead to breakage, if you tell make
> that your recipe will create M2-Planet but it instead creates bin/M2-
> Planet, which is a completely different file.
>
> As a result, as Malcolm says, all recipes should build $@ and never
> some alternate version of that (like bin/$@ or whatever).
>
> If you really need the generated file to be bin/M2-Planet then your
> target should build bin/M2-Planet:
>
>   all: bin/M2-Planet
>
>   bin/M2-Planet: ...
>           $(CC) ... -o $@
>
> If you want to be able to run "make M2-Planet" you can create a
> shortcut like this:
>
>   M2-Planet: bin/M2-Planet

OK! Is that understood as a shortcut by make? So the "MUST ALWAYS build
the target" does not apply in this case?

Best regards
--
Tomas