[gentoo-dev] RFC: cartesian product extension to keyword system

[heroxbd <heroxbd@gentoo.org>]

Dear all,

In GLEP22[1], reasonable defaults has been introduced to prevent the
explosion of keywords. With the growth of Gentoo Prefix, however, a
substantial amount of keywords are introduced. Among them, duplex
information exists. For example, an ebuild keyworded x86-linux(Gentoo
Prefix on x86 linux) will certainly build on x86 (Gentoo vanilla on x86
linux). Furthermore if the ebuild has "amd64" keyword, it will certainly
build on amd64-linux too.

This duplication becomes more manifested during the development of
Gentoo Prefix on arm. Introducing an arm-linux keyword is objected by
developers because we are having too many keywords[2]. But it is far
from consensus yet, as people are already adding arm-linux to
ebuilds[2].

There were also a proposal to treat arm the same as arm-linux, but
received more objections for its vagueness.

Therefore we propose the following cartesian product extension to
keyword system.

a. introducing four more variables, in order, KEYWORDS_ARCH,
   KEYWORDS_KERNEL, KEYWORDS_USERLAND, KEYWORDS_LIBC. An order relation
   is defined as arch > kernel > userland > libc

b. KEYWORDS_var1 must be defined if KEYWORDS_var2 is defined and var2 <
   var1. Otherwise it can be omitted.

c. KEYWORDS_PROD is defined as cartesian product of KEYWORDS_ARCH,
   KEYWORDS_KERNEL, KEYWORDS_USERLAND, KEYWORDS_LIBC. Omitted variable
   is interpreted as empty and not counted in the product. e.g., if
   KEYWORDS_USERLAND and KEYWORDS_LIBC are not defined, KEYWORDS_PROD is
   the product of KEYWORDS_ARCH and KEYWORDS_KERNEL.

c1. "~" is attached to KEYWORDS_PROD elements if any of its oprand has "~".

d. KEYWORDS is redefined as union of KEYWORDS_PROD and KEYWORDS (for
   backward compatibility)

e. reasonable defaults in GLEP22 applys.

Therefore, for sys-devel/bison, the keywords proposed will be:

KEYWORDS="~hppa-hpux ~m68k-mint ~ppc-aix ~x64-solaris ~x86-interix

KEYWORDS_ARCH="~alpha ~amd64 ~arm ~hppa ~ia64 ~m68k ~mips ~ppc ~ppc64 ~s390 ~sh ~sparc ~x86"

KEYWORDS_KERNEL="~linux ~solaris ~freebsd ~fbsd ~macos"

Problems remaining:

a. how to do stablization in this case?

b. how to handle things that does not exist? e.g. sparc-macosx?

c. how to clean up confusions? e.g. x64-solaris vs amd64-solaris,
   freebsd (Gentoo Prefix on FreeBSD) vs fbsd (Gentoo/FreeBSD)

Thanks,
Benda

1. http://www.gentoo.org/proj/en/glep/glep-0022.html

2. see sys-devel/bison, ~alpha ~amd64 ~amd64-fbsd ~amd64-linux ~arm ~arm-linux
   ~hppa ~hppa-hpux ~ia64 ~ia64-hpux ~ia64-linux ~m68k ~m68k-mint ~mips
   ~ppc ~ppc-aix ~ppc-macos ~ppc64 ~s390 ~sh ~sparc ~sparc-fbsd
   ~sparc-solaris ~sparc64-solaris ~x64-freebsd ~x64-macos ~x64-solaris
   ~x86 ~x86-fbsd ~x86-freebsd ~x86-interix ~x86-linux ~x86-macos
   ~x86-solaris