Re: ORed build profiles

[Matthias Klose <doko@debian.org>]

On 11/24/25 00:12, Johannes Schauer Marin Rodrigues wrote:
> Quoting Ben Hutchings (2025-11-24 00:00:56)
> > On Sun, 2025-11-23 at 08:07 +0100, Matthias Klose wrote:
> > [...]
> > > However when adding additional pkg.llvm.noflang, pkg.llvm.nolld, ...
> > > build profiles for some more fine grained control (attached diff), as in
> > >
> > >     Package: lld-21
> > >     Build-Profiles: <!pkg.llvm.noclang> + <!pkg.llvm.nolld>
> > >
> > > then all the packages with an ORed build profile are NOT built by
> > > default.  I'm not expecting this.  dpkg doesn't complain about the
> > > syntax of this field.
> > >
> > > Looking at
> > > https://wiki.debian.org/BuildProfileSpec#The_Package-List_field
> > >
> > > the spec seems to be a little bit ambiguous about that field, not giving
> > > a spec, but just some examples, and no example for ORed build profiles,
> > > and not explaining what the examples are supposed to do.
> > >
> > > There's also nothing told about the precedence of the operators, (NOT
> > > (!), OR (+), AND (,)).
> > [...]
> >
> > For the Build-Profiles field, "the same restriction formula syntax from
> > the Build-Depends field is used", and I think that is adequately
> > documented.
> >
> > For the Package-List field I think the syntax is changed just to avoid
> > whitespace in the expression.
>
> Yes, that was the reasoning we used back then.
>
> There is also a good chance that build profiles will be part of Debian Policy
> soon. The latest version of the text (last message in the bug) is much better
> written than the BuildProfileSpec page in the Debian wiki and might thus be a
> better document to read to understand how it is supposed to work:
>
> https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=757760

thanks for the pointer to the report.

sorry, the last proposed text again doesn't explicitly talk about the 
Build-Profiles attribute.  There are too many "I think"'s here, and e.g. 
claims that these don't support ORs, while the spec *is* talking about 
ANDing and ORing.

"Thinking" in a spec should be avoided. Plus dpkg apparently doesn't 
properly check the supposed/intended syntax.

Please be explicit about the Build-Profiled attribute, and give some 
examples like you did for the Build-Depends field.

The spec should be explicit about
 - Are <> part of the list?
 - Where is whitespace allowed/prohibited?
 - Having examples for the Build-Profiles attribute, without referencing
   the Build-Depends attribute.

Please update the spec.

Matthias