Breaking things down a bit, one thing I keep running into with our current 
codebase and metadata is that overrides are not clear. In my previous email,
the example was:

do_configure_class-native

A human can usually spot "class-native" is and "configure" or 
"configure_class-native" is not. Bitbake's parser struggles. It has huge 
internal lists including variables like x86_64 where it has to track 
whether "64" in an override.

One way of fixing this is to be explicit about overrides and use a different 
separator. See an example patch below I made to the quilt recipe using ":" 
instead to see how it looks. Personally, I think this looks like an improvement.

There are two challenges:

a) The work of migration. Do we migrate piecemeal or with a flag day? I'm not
sure piecemeal is even possible unfortunately.

b) Some of the packaging code (at the very least) needs rewriting as it accesses
both RDEPENDS_${PN} and puts ${PN} in OVERRIDES and accesses RDEPENDS. I'm not
sure what else may be assuming this works.

This change does buy us cleaner looking metadata and ultimately, a faster
and cleaner internal bitbake that at least would use less memory. It could set
the stage to allow the defval idea I mentioned in a previous mail to happen.

It is a huge change and would need a lot of work to make it happen. Is it worth 
doing? Not sure. I'm putting it out there for discussion.

It is also going to be tempting that "if we're breaking things, lets break lots".
I want to be mindful that tempting as that may be, if users can't convert clearly,
it will be worlds of pain. The benefit of this change is that at least in the
general case, the transition should be clear. Taking steps rather than changing the
world may therefore be a better idea...

Cheers,

Richard


diff --git a/meta/recipes-devtools/quilt/quilt.inc b/meta/recipes-devtools/quilt/quilt.inc
index d7ecda7aaa6..f85de384d26 100644
--- a/meta/recipes-devtools/quilt/quilt.inc
+++ b/meta/recipes-devtools/quilt/quilt.inc
@@ -14,36 +14,36 @@ SRC_URI = "${SAVANNAH_GNU_MIRROR}/quilt/quilt-${PV}.tar.gz \
file://0001-tests-Allow-different-output-from-mv.patch \
"

-SRC_URI_append_class-target = " file://gnu_patch_test_fix_target.patch"
+SRC_URI:append:class-target = " file://gnu_patch_test_fix_target.patch"

SRC_URI[md5sum] = "6800c2404a2c0598ab2eff92a636ba70"
SRC_URI[sha256sum] = "314b319a6feb13bf9d0f9ffa7ce6683b06919e734a41275087ea457cc9dc6e07"

inherit autotools-brokensep ptest

-INHIBIT_AUTOTOOLS_DEPS_class-native = "1"
-PATCHTOOL_class-native = "patch"
+INHIBIT_AUTOTOOLS_DEPS:class-native = "1"
+PATCHTOOL:class-native = "patch"

CLEANBROKEN = "1"

EXTRA_OECONF = "--with-perl='${USRBINPATH}/env perl' --with-patch=patch"
-EXTRA_OECONF_append_class-native = " --disable-nls"
+EXTRA_OECONF:append:class-native = " --disable-nls"
EXTRA_AUTORECONF += "--exclude=aclocal"

CACHED_CONFIGUREVARS += "ac_cv_path_BASH=/bin/bash ac_cv_path_COLUMN=column"

# Make sure we don't have "-w" in shebang lines: it breaks using
# "/usr/bin/env perl" as parser
-do_configure_prepend () {
+do_configure:prepend () {
find ${S} -name "*.in" -exec sed -i -e "1s,^#\!.*@PERL@ -w$,#\! @PERL@\nuse warnings;," {} \;
}

# Don't setup symlinks to host utilities, we don't need them
-do_configure_append () {
+do_configure:append () {
sed -e 's,^COMPAT_SYMLINKS.*:=.*,COMPAT_SYMLINKS :=,' -i ${S}/Makefile
}

-do_configure_class-native () {
+do_configure:class-native () {
oe_runconf
}

@@ -54,7 +54,7 @@ do_install () {
rm -rf ${D}/${datadir}/emacs
}

-do_install_append_class-native () {
+do_install:append:class-native () {
# Dummy quiltrc file for patch.bbclass
install -d ${D}${sysconfdir}/
touch ${D}${sysconfdir}/quiltrc
@@ -75,16 +75,16 @@ do_install_ptest() {

PACKAGES += "guards guards-doc"

-FILES_${PN} = "${sysconfdir} ${datadir}/quilt \
+FILES:${PN} = "${sysconfdir} ${datadir}/quilt \
${bindir}/quilt ${libdir}/quilt"
-FILES_guards = "${bindir}/guards"
-FILES_${PN}-doc = "${mandir}/man1/quilt.1 ${docdir}/${BPN}"
-FILES_guards-doc = "${mandir}/man1/guards.1"
+FILES:guards = "${bindir}/guards"
+FILES:${PN}-doc = "${mandir}/man1/quilt.1 ${docdir}/${BPN}"
+FILES:guards-doc = "${mandir}/man1/guards.1"

-RDEPENDS_${PN} = "bash patch diffstat bzip2 util-linux less"
-RDEPENDS_${PN}_class-native = "diffstat-native patch-native bzip2-native"
+RDEPENDS:${PN} = "bash patch diffstat bzip2 util-linux less"
+RDEPENDS:${PN}:class-native = "diffstat-native patch-native bzip2-native"

-RDEPENDS_${PN}-ptest = "make file sed gawk diffutils findutils ed perl \
+RDEPENDS:${PN}-ptest = "make file sed gawk diffutils findutils ed perl \
perl-module-filehandle perl-module-getopt-std \
perl-module-posix perl-module-file-temp \
perl-module-text-parsewords perl-module-overloading \