qemu-e2k/scripts
Eric Blake 30594fe1cd qapi: Prefer typesafe upcasts to qapi base classes
A previous patch (commit 1e6c1616) made it possible to
directly cast from a qapi flat union type to its base type.
However, it requires the use of a C cast, which turns off
compiler type-safety checks.  Fortunately, no such casts
exist, just yet.

Regardless, add inline type-safe wrappers named
qapi_FOO_base() for any union type FOO that has a base,
which can be used for a safer upcast, and enhance the
testsuite to cover the new functionality.

A future patch will extend the upcast support to structs,
where such conversions do exist already.

Note that C makes const-correct upcasts annoying because
it lacks overloads; these functions cast away const so that
they can accept user pointers whether const or not, and the
result in turn can be assigned to normal or const pointers.
Alternatively, this could have been done with macros, but
type-safe macros are hairy, and not worthwhile here.

This patch just adds upcasts.  None of our code needed to
downcast from a base qapi class to a child.  Also, in the
case of grandchildren (such as BlockdevOptionsQcow2), the
caller will need to call two functions to get to the inner
base (although it wouldn't be too hard to generate a
qapi_FOO_base_base() if desired).  If a user changes qapi
to alter the base class hierarchy, such as going from
'A -> C' to 'A -> B -> C', it will change the type of
'qapi_C_base()', and the compiler will point out the places
that are affected by the new base.

One alternative was proposed, but was deemed too ugly to use
in practice: the generators could output redundant
information using anonymous types:
| struct Child {
|     union {
|         struct {
|             Type1 parent_member1;
|             Type2 parent_member2;
|         };
|         Parent base;
|     };
| };
With that ugly proposal, for a given qapi type, obj->member
and obj->base.member would refer to the same storage; allowing
convenience in working with members without needing 'base.'
allowing typesafe upcast without needing a C cast by accessing
'&obj->base', and allowing downcasts from the parent back to
the child possible through container_of(obj, Child, base).

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-10-git-send-email-eblake@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
2015-11-02 08:30:26 +01:00
..
kvm kvm_stat: add kvm_stat.1 man page 2015-03-10 10:49:25 +01:00
qemu-guest-agent qemu-ga: sample fsfreeze hooks 2013-01-08 16:38:12 -06:00
qemugdb gdb command: qemu handlers 2015-10-29 17:59:27 +00:00
qmp qmp-shell: add documentation 2015-09-04 13:18:04 +02:00
tracetool trace: add DTrace reserved words for .d files 2015-03-02 15:39:43 -06:00
acpi_extract.py i386: Add an ACPI_EXTRACT_NAME_BUFFER16 directive. 2014-11-02 11:52:24 +02:00
acpi_extract_preprocess.py i386: add ACPI table files from seabios 2013-10-14 17:48:51 +03:00
analyse-9p-simpletrace.py scripts/analyse-9p-simpletrace.py: Add symbolic names for 9p operations. 2011-12-21 12:37:23 +05:30
analyze-migration.py Teach analyze-migration.py about section footers 2015-06-12 06:54:01 +02:00
check-qerror.sh qerror: add check-qerror.sh to verify alphabetical order 2012-01-18 10:23:39 -02:00
checkpatch.pl checkpatch: port fix from kernel "## is not a valid modifier" 2015-10-12 18:29:26 +02:00
cleanup-trace-events.pl cleanup-trace-events.pl: Tighten search for trace event call 2014-09-26 09:34:38 +01:00
cocci-macro-file.h add macro file for coccinelle 2015-09-09 15:34:55 +02:00
coverity-model.c coverity: fix address_space_rw model 2015-05-05 10:42:11 +02:00
create_config module: implement module loading 2014-02-20 13:14:18 +01:00
disas-objdump.pl disas-objdump: Pass --adjust-vma to objdump 2013-08-24 07:26:45 +02:00
dump-guest-memory.py scripts/dump-guest-memory.py: fix after RAMBlock change 2015-09-09 15:34:55 +02:00
extract-vsssdk-headers Add a script to extract VSS SDK headers on POSIX system 2013-09-09 14:17:56 -05:00
feature_to_c.sh exec: move include files to include/exec/ 2012-12-19 08:31:31 +01:00
get_maintainer.pl get_maintainer.pl: \C is deprecated 2015-09-25 12:04:41 +02:00
gtester-cat test makefile overhaul 2012-03-30 08:14:11 -05:00
hxtool vl.c: In qemu -h output, only print options for the arch we are running as 2011-12-19 10:27:33 -06:00
make-release make-release: Record SeaBIOS version 2014-03-31 15:02:04 +01:00
make_device_config.sh build: pass .d file name to scripts/make_device_config.sh, fix makefile target 2015-03-18 12:07:25 +01:00
ordereddict.py qapi: Clean up qapi.py per pep8 2015-10-12 18:44:54 +02:00
qapi-commands.py qapi: More robust conditions for when labels are needed 2015-11-02 08:30:26 +01:00
qapi-event.py qapi: Share gen_visit_fields() 2015-10-12 18:46:50 +02:00
qapi-introspect.py qapi: Use predicate callback to determine visit filtering 2015-10-15 08:39:07 +02:00
qapi-types.py qapi: Prefer typesafe upcasts to qapi base classes 2015-11-02 08:30:26 +01:00
qapi-visit.py qapi-visit: Split off visit_type_FOO_fields forward decl 2015-11-02 08:30:26 +01:00
qapi.py qapi: Reserve 'q_*' and 'has_*' member names 2015-11-02 08:30:26 +01:00
qemu-binfmt-conf.sh scripts/qemu-binfmt-conf.sh: Add AArch64 registration 2014-03-17 16:31:53 +00:00
qemu-gdb.py gdb command: qemu handlers 2015-10-29 17:59:27 +00:00
qtest.py qtest: Add scripts/qtest.py 2015-02-16 15:07:18 +00:00
refresh-pxe-roms.sh roms: rewrite scripts/refresh-pxe-roms.sh 2013-09-30 09:44:35 +02:00
shaderinclude.pl opengl: add shader build infrastructure 2015-05-05 09:03:32 +02:00
signrom.py signrom: Rewrite as python script 2012-04-16 15:41:20 +02:00
simpletrace.py simpletrace: add simpletrace.py --no-header option 2014-08-12 14:26:11 +01:00
switch-timer-api misc: Fix case Qemu -> QEMU 2014-02-15 16:10:25 +04:00
texi2pod.pl Support utf8 chars in pod docs 2012-03-24 14:10:25 +00:00
tracetool.py trace: Multi-backend tracing 2014-06-09 15:43:40 +02:00
update-acpi.sh acpi: add rules to compile ASL source 2013-10-14 17:48:51 +03:00
update-linux-headers.sh linux-headers: add unistd.h 2015-10-22 14:34:48 +03:00
vmstate-static-checker.py vmstate-static-checker: update whitelist 2015-02-05 17:16:14 +01:00