[RFC PATCH 0/4] qom: Introduce object_class_property_deprecate()

[Philippe Mathieu-Daudé]

Hi,

There will always be a need to deprecate things. Here I'm
tackling the QOM (class) properties, since they can be set
from some CLI options (-object -device -global ...).

As an experiment, we add object_class_property_deprecate()
to register a class property as deprecated (since some version),
then we deprecate the TYPE_PFLASH_CFI02 'width' property, and
finally as a bonus we emit a warning when the deprecation period
is over, as a reminder. (For that we introduce few 'versions'
helpers).

Output example:

$ qemu-system-arm -M musicpal,accel=qtest -S \
  -drive if=pflash,driver=null-co,read-zeroes=on,size=8M \
  -global driver=cfi.pflash02,property=width,value=2
qemu-system-arm: warning: Property 'cfi.pflash02.width' is deprecated (renamed 
as 'cfi.pflash02.device-width').

$ qemu-system-arm -M musicpal,accel=qtest -S \
  -drive if=pflash,driver=null-co,read-zeroes=on,size=8M \
  -global driver=cfi.pflash02,property=device-width,value=2
qemu-system-arm: warning: Property 'cfi.pflash02.width' has been deprecated in 
release v8.0 and can be removed.

Thought?

Regards,

Phil.

[earlier inspiration: 
https://lore.kernel.org/qemu-devel/Y7wlnqwU+/auE0Jj@redhat.com/]

Philippe Mathieu-Daudé (4):
  qom: Introduce object_class_property_deprecate()
  hw/block: Rename TYPE_PFLASH_CFI02 'width' property as 'device-width'
  util: Introduce helpers to compare QEMU versions
  qom: Warn when deprecated class property can be removed

 hw/block/pflash_cfi02.c     |  8 +++++++-
 include/qemu/qemu-version.h | 36 ++++++++++++++++++++++++++++++++++++
 include/qom/object.h        | 17 +++++++++++++++++
 qom/object.c                | 30 ++++++++++++++++++++++++++++++
 util/meson.build            |  1 +
 util/qemu-version.c         | 37 +++++++++++++++++++++++++++++++++++++
 6 files changed, 128 insertions(+), 1 deletion(-)
 create mode 100644 include/qemu/qemu-version.h
 create mode 100644 util/qemu-version.c

-- 
2.38.1