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We have two issues with our qapi union layout:
1) Even though the QMP wire format spells the tag 'type', the
C code spells it 'kind', requiring some hacks in the generator.
2) The C struct uses an anonymous union, which places all tag
values in the same namespace as all non-variant members. This
leads to spurious collisions if a tag value matches a non-variant
member's name.
This patch is the back end for a series that converts to a
saner qapi union layout. Now that all clients have been
converted to use 'type' and 'obj->u.value', we can drop the
temporary parallel support for 'kind' and 'obj->value'.
Given a simple union qapi type:
{ 'union':'Foo', 'data': { 'a':'int', 'b':'bool' } }
this is the overall effect, when compared to the state before
this series of patches:
| struct Foo {
|- FooKind kind;
|- union { /* union tag is @kind */
|+ FooKind type;
|+ union { /* union tag is @type */
| void *data;
| int64_t a;
| bool b;
|- };
|+ } u;
| };
The testsuite still contains some examples of artificial restrictions
(see flat-union-clash-type.json, for example) that are no longer
technically necessary, now that there is no longer a collision between
enum tag values and non-variant member names; but fixing this will be
done in later patches, in part because some further changes are required
to keep QAPISchema*.check() from asserting. Also, a later patch will
add a reservation for the member name 'u' to avoid a collision between a
user's non-variant names and our internal choice of C union name.
Note, however, that we do not rename the generated enum, which
is still 'FooKind'. A further patch could generate implicit
enums as 'FooType', but while the generator already reserved
the '*Kind' namespace (commit
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| .. | ||
| kvm | ||
| qemu-guest-agent | ||
| qemugdb | ||
| qmp | ||
| tracetool | ||
| acpi_extract_preprocess.py | ||
| acpi_extract.py | ||
| analyse-9p-simpletrace.py | ||
| analyze-migration.py | ||
| check-qerror.sh | ||
| checkpatch.pl | ||
| cleanup-trace-events.pl | ||
| cocci-macro-file.h | ||
| coverity-model.c | ||
| create_config | ||
| disas-objdump.pl | ||
| dump-guest-memory.py | ||
| extract-vsssdk-headers | ||
| feature_to_c.sh | ||
| get_maintainer.pl | ||
| gtester-cat | ||
| hxtool | ||
| make_device_config.sh | ||
| make-release | ||
| ordereddict.py | ||
| qapi-commands.py | ||
| qapi-event.py | ||
| qapi-introspect.py | ||
| qapi-types.py | ||
| qapi-visit.py | ||
| qapi.py | ||
| qemu-binfmt-conf.sh | ||
| qemu-gdb.py | ||
| qtest.py | ||
| refresh-pxe-roms.sh | ||
| shaderinclude.pl | ||
| signrom.py | ||
| simpletrace.py | ||
| switch-timer-api | ||
| texi2pod.pl | ||
| tracetool.py | ||
| update-acpi.sh | ||
| update-linux-headers.sh | ||
| vmstate-static-checker.py | ||