Re: debian/rules and DEB_BUILD_PROFILES vs _OPTIONS

[Christian Kastner <ckk@debian.org>]

On 2020-09-08 08:36, Niels Thykier wrote:
> Fundamentally, the difference between the two are:
> 
>  * _PROFILES is a "new"[0] thing with a specific purpose to reduce
>    build-dependencies (at least in this case).  It ends up in d/rules
>    for skipping builds of specific packages (e.g. "nopython")
> 
>  * _OPTIONS is the thing that has been here since the "dawn of time" to
>    enable the builder to tweak the build in a standardized way.
> 
> (Note that their definitions do not overlap)
> 
> Basically, we ended up in the situation like this with nocheck[1]:
> 
>  * We had _OPTIONS with nocheck for at least a decade and probably more.
>    - I.e. _OPTIONS is what everyone wrote in their d/rules file to
>      implement policy.
> 
>  * We invented _PROFILES and supported nocheck to assist cross-builders
>    and bootstrappers, who generally want as few build-depends as
>    possible even at the expense of running tests (cross-builders often
>    cannot run them anyway).
>    - I.e. _PROFILES is what the dependency resolvers look for when
>      deciding which build-depends to install.
> 
> And that is how you end up with WET Debian packaging.
> 
> I hope that cleared the relationship between _OPTIONS and _PROFILES and
> how we got here.

Yes, thank you for the background -- that was really helpful.

Coming back to the practical problem from a maintainer's point of view,
unless I'm mistaken, that means:


nocheck
-------

A recipe such as

    override_dh_auto_test:
    ifeq (,$(filter nocheck,$(DEB_BUILD_PROFILES)))
        dh_auto_test
    endif

is sufficient as "dh_auto_test" will honor possibly present _OPTIONS, but

    override_dh_auto_test:
    ifeq (,$(filter nocheck,$(DEB_BUILD_PROFILES)))
        custom-test-command
    endif

is not, as "custom-test-command" will be executed even if
DEB_BUILD_OPTIONS=nocheck is set.


nodoc
-----

As recipes frequently follow the pattern of

    override_dh_auto_build:
        dh_auto_build
    ifeq (,$(filter nodoc,$(DEB_BUILD_PROFILES)))
        build-docs-command
    endif

DEB_BUILD_OPTIONS=nodoc gets ignored.


vice versa
-----------
And the same applies when _OPTIONS is filtered instead of _PROFILES.


Did I get that right?

Christian