We were previously creating all unions with an empty list for
local_members.  However, it will make it easier to unify struct
and union generation if we include the generated tag member in
local_members.  That way, we can have a common code pattern:
visit the base (if any), visit the local members (if any), visit
the variants (if any).  The local_members of a flat union
remains empty (because the discriminator is already visited as
part of the base).  Then, by visiting tag_member.check() during
AlternateType.check(), we no longer need to call it during
Variants.check().

The various front end entities now exist as follows:
struct: optional base, optional local_members, no variants
simple union: no base, one-element local_members, variants with tag_member
  from local_members
flat union: base, no local_members, variants with tag_member from base
alternate: no base, no local_members, variants

With the new local members, we require a bit of finesse to
avoid assertions in the clients.

No change to generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-2-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Our generated list visitors have the same problem as has been
mentioned elsewhere (see commit 2f52e205): they allocate data
even on failure. An upcoming patch will correct things to
provide saner guarantees, but first we need to expose the
behavior in the testsuite to ensure we aren't introducing any
memory usage bugs.

There are more test cases throughout the test-qmp-input-* tests
that already deal with partial allocation; a later commit will
clean up all visit_type_FOO(), without marking all of the tests
with FIXME at this time.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1446791754-23823-10-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

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.

Make the conversion to the new layout for qapi-visit.py.

Generated code changes look like:

|@@ -4912,16 +4912,16 @@ void visit_type_MemoryDeviceInfo(Visitor
|     if (!*obj) {
|         goto out_obj;
|     }
|-    visit_type_MemoryDeviceInfoKind(v, &(*obj)->kind, "type", &err);
|+    visit_type_MemoryDeviceInfoKind(v, &(*obj)->type, "type", &err);
|     if (err) {
|         goto out_obj;
|     }
|-    if (!visit_start_union(v, !!(*obj)->data, &err) || err) {
|+    if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
|         goto out_obj;
|     }
|-    switch ((*obj)->kind) {
|+    switch ((*obj)->type) {
|     case MEMORY_DEVICE_INFO_KIND_DIMM:
|-        visit_type_PCDIMMDeviceInfo(v, &(*obj)->dimm, "data", &err);
|+        visit_type_PCDIMMDeviceInfo(v, &(*obj)->u.dimm, "data", &err);
|         break;
|     default:
|         abort();
|@@ -4930,7 +4930,7 @@ out_obj:
|     error_propagate(errp, err);
|     err = NULL;
|     if (*obj) {
|-        visit_end_union(v, !!(*obj)->data, &err);
|+        visit_end_union(v, !!(*obj)->u.data, &err);
|     }
|     error_propagate(errp, err);
|     err = NULL;
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-14-git-send-email-eblake@redhat.com>
[Commit message tweaked slightly]
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

The code for visiting the base class of a child struct created
visit_type_Base_fields() which covers all fields of Base; while
the code for visiting the base class of a flat union created
visit_type_Union_fields() covering all fields of the base
except the discriminator.  But since the base class includes
the discriminator of a flat union, we can just visit the entire
base, without needing a separate visit of the discriminator.
Not only is consistently visiting all fields easier to
understand, it lets us share code.

The generated code in qapi-visit.c loses several now-unused
visit_type_UNION_fields(), along with changes like:

|@@ -1654,11 +1557,7 @@ void visit_type_BlockdevOptions(Visitor
|     if (!*obj) {
|         goto out_obj;
|     }
|-    visit_type_BlockdevOptions_fields(v, obj, &err);
|-    if (err) {
|-        goto out_obj;
|-    }
|-    visit_type_BlockdevDriver(v, &(*obj)->driver, "driver", &err);
|+    visit_type_BlockdevOptionsBase_fields(v, (BlockdevOptionsBase **)obj, &err);
|     if (err) {
|         goto out_obj;
|     }

and forward declarations where needed.  Note that the cast of obj
to BASE ** is necessary to call visit_type_BASE_fields() (and we
can't use our upcast wrappers, because those work on pointers while
we have a pointer-to-pointer).
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-12-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Rather than storing a base class as a pointer to a box, just
store the fields of that base class in the same order, so that
a child struct can be directly cast to its parent.  This gives
less malloc overhead, less pointer dereferencing, and even less
generated code.  Compare to the earlier commit 1e6c1616 "qapi:
Generate a nicer struct for flat unions" (although that patch
had fewer places to change, as less of qemu was directly using
qapi structs for flat unions).  It also allows us to turn on
automatic type-safe wrappers for upcasting to the base class
of a struct.

Changes to the generated code look like this in qapi-types.h:

| struct SpiceChannel {
|-    SpiceBasicInfo *base;
|+    /* Members inherited from SpiceBasicInfo: */
|+    char *host;
|+    char *port;
|+    NetworkAddressFamily family;
|+    /* Own members: */
|     int64_t connection_id;

as well as additional upcast functions like qapi_SpiceChannel_base().
Meanwhile, changes to qapi-visit.c look like:

| static void visit_type_SpiceChannel_fields(Visitor *v, SpiceChannel **obj, Error **errp)
| {
|     Error *err = NULL;
|
|-    visit_type_implicit_SpiceBasicInfo(v, &(*obj)->base, &err);
|+    visit_type_SpiceBasicInfo_fields(v, (SpiceBasicInfo **)obj, &err);
|     if (err) {

(the cast is necessary, since our upcast wrappers only deal with a
single pointer, not pointer-to-pointer); plus the wholesale
elimination of some now-unused visit_type_implicit_FOO() functions.

Without boxing, the corner case of one empty struct having
another empty struct as its base type now requires inserting a
dummy member (previously, the 'Base *base' member sufficed).

And now that we no longer consume a 'base' member in the generated
C struct, we can delete the former negative struct-base-clash-base
test.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-11-git-send-email-eblake@redhat.com>
[Commit message tweaked slightly]
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We generate a static visit_type_FOO_fields() for every type
FOO.  However, sometimes we need a forward declaration. Split
the code to generate the forward declaration out of
gen_visit_implicit_struct() into a new gen_visit_fields_decl(),
and also prepare for a forward declaration to be emitted
during gen_visit_struct(), so that a future patch can switch
from using visit_type_FOO_implicit() to the simpler
visit_type_FOO_fields() as part of unboxing the base class
of a struct.

No change to generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-8-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We were using regular expressions to see if ret included
any earlier text that emitted a 'goto out;' line, to decide
whether we needed to output an 'out:' label.  But this is
fragile, if the ret text can possibly combine more than one
generated function body, where the first function used a
goto but the second does not.  Change the code to just check
for the known conditions which cause an error check to be
needed.  Besides, it's slightly more efficient to use plain
checks than regular expression searching.

No change to generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1445898903-12082-4-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

A future patch will enable error reporting from the various
QAPISchema*.check() methods.  But to report an error related
to an implicit type, we'll need to associate a location with
the type (the same location as the top-level entity that is
causing the creation of the implicit type), and once we do
that, keying off of whether foo.info exists is no longer a
viable way to determine if foo is an implicit type.

Instead, add an is_implicit() method to QAPISchemaEntity, and use it.
It can be overridden later for ObjectType and EnumType, when implicit
instances of those classes gain info.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1444710158-8723-8-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Previously, qapi-types and qapi-visit filtered out implicit
objects during visit_object_type() by using 'info' (works since
implicit objects do not [yet] have associated info); meanwhile
qapi-introspect filtered out all schema types on the first pass
by returning a python type from visit_begin(), which was then
used at a distance in QAPISchema.visit() to do the filtering.

Rather than keeping these ad hoc approaches, add a new visitor
callback visit_needed() which returns False to skip a given
entity, and which defaults to True unless overridden.  Use the
new mechanism to simplify all three filtering visitors.

No change to the generated code.
Suggested-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1444710158-8723-2-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Commit e36c714e causes 'qemu -netdev help' to dump core, because the
call to visit_end_union() is no longer conditional on whether *obj was
allocated.

Reported by Marc-André Lureau <marcandre.lureau@gmail.com>
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1444861825-19256-1-git-send-email-eblake@redhat.com>
[Commit message tweaked to say 'help' instead of '?']
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Consolidate the code between visit, command marshalling, and
event generation that iterates over the members of a struct.
It reduces code duplication in the generator, so that a future
patch can reduce the size of generated code while touching only
one instead of three locations.

There are no changes to the generated marshal code.

The visitor code becomes slightly more verbose, but remains
semantically equivalent, and is actually easier to read as
it follows a more common idiom:

|     visit_optional(v, &(*obj)->has_device, "device", &err);
|-    if (!err && (*obj)->has_device) {
|-        visit_type_str(v, &(*obj)->device, "device", &err);
|-    }
|     if (err) {
|         goto out;
|     }
|+    if ((*obj)->has_device) {
|+        visit_type_str(v, &(*obj)->device, "device", &err);
|+        if (err) {
|+            goto out;
|+        }
|+    }

The event code becomes slightly more verbose, but this is
arguably a bug fix: although the visitors are not well
documented, use of an optional member should not be attempted
unless guarded by a prior call to visit_optional().  Works only
because the output qmp visitor has a no-op visit_optional():

|+    visit_optional(v, &has_offset, "offset", &err);
|+    if (err) {
|+        goto out;
|+    }
|     if (has_offset) {
|         visit_type_int(v, &offset, "offset", &err);
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-17-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

qapi-commands has a nice helper gen_err_check(), but did not
use it everywhere. In fact, using it in more places makes it
easier to reduce the lines of code used for generating error
checks.  This in turn will make it easier for later patches
to consolidate another common pattern among the generators.

The generated code has fewer blank lines in qapi-event.c functions,
but has no semantic difference.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-16-git-send-email-eblake@redhat.com>
[Drop another blank line for symmetry]
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We had some pointless differences in the generated code for visit,
command marshalling, and events; unifying them makes it easier for
future patches to consolidate to common helper functions.
This is one patch of a series to clean up these differences.

This patch reduces the number of push_indent()/pop_indent() pairs
so that generated code is typically already at its natural output
indentation in the python files.  It is easier to reason about
generated code if the reader does not have to track how much
spacing will be inserted alongside the code, and moreso when all
of the generators use the same patterns (qapi-type and qapi-event
were already using in-place indentation).

Arguably, the resulting python may be a bit harder to read with C
code at the same indentation as python; on the other hand, not
having to think about push_indent() is a win, and most decent
editors provide syntax highlighting that makes it easier to
visually distinguish python code from string literals that will
become C code.

There is no change to the generated output.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-15-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We had some pointless differences in the generated code for visit,
command marshalling, and events; unifying them makes it easier for
future patches to consolidate to common helper functions.
This is one patch of a series to clean up these differences.

This patch adjusts gen_visit_union() to use the same indentation
as other functions, namely, by jumping early to the error label
if the object was not set rather than placing the rest of the
body inside an if for when it is set.

No change in semantics to the generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-14-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We had some pointless differences in the generated code for visit,
command marshalling, and events; unifying them makes it easier for
future patches to consolidate to common helper functions.
This is one patch of a series to clean up these differences.

This patch names the goto labels 'out' (not 'clean') and 'out_obj'
(not 'out_end').  Additionally, the generator was inconsistent on
whether labels had a leading space [our HACKING is silent; while
emacs 'gnu' style adds the space to avoid littering column 1].
For minimal churn, prefer no leading space; this also matches
the style that is more prevalent in current qemu.git.

No change in semantics to the generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-13-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

We had some pointless differences in the generated code for visit,
command marshalling, and events; unifying them makes it easier for
future patches to consolidate to common helper functions.
This is one patch of a series to clean up these differences.

This patch names the local visitor variable 'v' rather than 'm'.
Related objects, such as 'QapiDeallocVisitor', are also named by
their initials instead of an unrelated leading m.

No change in semantics to the generated code.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1443565276-4535-12-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Move gen_visit_decl() to a better place.  Inline
generate_visit_struct_body().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Message-Id: <1442401589-24189-15-git-send-email-armbru@redhat.com>

Generate just 'FOO' instead of 'struct FOO' when possible.

Drop helper functions that are now unused.

Make pep8 and pylint reasonably happy.

Rename generate_FOO() functions to gen_FOO() for consistency.

Use more consistent and sensible variable names.

Consistently use c_ for mapping keys when their value is a C
identifier or type.

Simplify gen_enum() and gen_visit_union()

Consistently use single quotes for C text string literals.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Message-Id: <1442401589-24189-14-git-send-email-armbru@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Fixes flat unions to visit the base's base members (the previous
commit merely added them to the struct).  Same test case.

Patch's effect on visit_type_UserDefFlatUnion():

     static void visit_type_UserDefFlatUnion_fields(Visitor *m, UserDefFlatUnion **obj, Error **errp)
     {
         Error *err = NULL;

    +    visit_type_int(m, &(*obj)->integer, "integer", &err);
    +    if (err) {
    +        goto out;
    +    }
         visit_type_str(m, &(*obj)->string, "string", &err);
         if (err) {
             goto out;

Test cases updated for the bug fix.

Fixes alternates to generate a visitor for their implicit enumeration
type.  None of them are currently used, obviously.  Example:
block-core.json's BlockdevRef now generates
visit_type_BlockdevRefKind().

Code is generated in a different order now, and therefore has got a
few new forward declarations.  Doesn't matter.

The guard QAPI_VISIT_BUILTIN_VISITOR_DECL is renamed to
QAPI_VISIT_BUILTIN.

The previous commit's two ugly special cases exist here, too.  Mark
both TODO.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

The QAPI code generators work with a syntax tree (nested dictionaries)
plus a few symbol tables (also dictionaries) on the side.

They have clearly outgrown these simple data structures.  There's lots
of rummaging around in dictionaries, and information is recomputed on
the fly.  For the work I'm going to do, I want more clearly defined
and more convenient interfaces.

Going forward, I also want less coupling between the back-ends and the
syntax tree, to make messing with the syntax easier.

Create a bunch of classes to represent QAPI schemata.

Have the QAPISchema initializer call the parser, then walk the syntax
tree to create the new internal representation, and finally perform
semantic analysis.

Shortcut: the semantic analysis still relies on existing check_exprs()
to do the actual semantic checking.  All this code needs to move into
the classes.  Mark as TODO.

Simple unions are lowered to flat unions.  Flat unions and structs are
represented as a more general object type.

Catching name collisions in generated code would be nice.  Mark as
TODO.

We generate array types eagerly, even though most of them aren't used.
Mark as TODO.

Nothing uses the new intermediate representation just yet, thus no
change to generated files.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Clean up white-space, brace placement, and superfluous #ifdef
QAPI_TYPES_BUILTIN_CLEANUP_DEF.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Most functions that can return a pointer or set an Error ** value
are decent enough to guarantee a NULL return when reporting an error.
Not so with our generated qapi visitor functions.  If the caller
is not careful to clean up partially-allocated objects on error,
then the caller suffers a memory leak.

Properly fixing it is probably complex enough to save for a later
day, so merely document it for now.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1438295587-19069-1-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

The generated code passes mangled schema names to visit_type_enum()
and union's visit_start_struct().  Fix it to pass the names
unadulterated, like we do everywhere else.

Only qapi-schema-test.json actually has names where this makes a
difference: enum __org.qemu_x-Enum, flat union __org.qemu_x-Union2,
simple union __org.qemu_x-Union1 and its implicit enum
__org.qemu_x-Union1Kind.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Use set because that's what it is.  While there, rename to
implicit_structs_seen.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

The visit_type_implicit_FOO() are generated on demand, right before
their first use.  Used by visit_type_STRUCT_fields() when STRUCT has
base FOO, and by visit_type_UNION() when flat UNION has member a FOO.

If the schema defines FOO after its first use as struct base or flat
union member, visit_type_implicit_FOO() calls
visit_type_implicit_FOO() before its definition, which doesn't
compile.

Rearrange qapi-schema-test.json to demonstrate the bug.

Fix by generating the necessary forward declaration.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

A flat union's tag member gets renamed to 'kind' in the generated
code.  Breaks when another member named 'kind' exists.

Example, adapted from qapi-schema-test.json:

    { 'struct': 'UserDefUnionBase',
      'data': { 'kind': 'str', 'enum1': 'EnumOne' } }

We generate:

    struct UserDefFlatUnion
    {
        EnumOne kind;
        union {
            void *data;
            UserDefA *value1;
            UserDefB *value2;
            UserDefB *value3;
        };
        char *kind;
    };

Kill the silly rename.
Reported-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

gen_sync_call()'s parameter indent is useless: gen_sync_call() uses it
only as optional argument for push_indent() and pop_indent(), their
default is four, and gen_sync_call()'s only caller passes four.  Drop
the parameter.

gen_visitor_input_containers_decl()'s parameter obj is always
"QOBJECT(args)".  Use that, and drop the parameter.

Drop unused parameters of gen_marshal_output(),
gen_marshal_input_decl(), generate_visit_struct_body(),
generate_visit_list(), generate_visit_enum(), generate_declaration(),
generate_enum_declaration(), generate_decl_enum().

Drop unused variables in generate_event_enum_lookup(),
generate_enum_lookup(), generate_visit_struct_fields(), check_event().
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

Enhance the testsuite to cover downstream alternates, including
whether the branch name or type is downstream.  Update the
generator to mangle alternate names in the appropriate places.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Enhance the testsuite to cover downstream flat unions, including
the base type, discriminator name and type, and branch name and
type.  Update the generator to mangle the union names in the
appropriate places.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Enhance the testsuite to cover downstream simple unions, including
when a union branch is a downstream name.  Update the generator to
mangle the union names in the appropriate places.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Enhance the testsuite to cover downstream structs, including struct
members and base structs.  Update the generator to mangle the
struct names in the appropriate places.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Enhance the testsuite to cover a downstream enum type and enum
string.  Update the generator to mangle the enum name in the
appropriate places.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NEric Blake <eblake@redhat.com>

Now that the two functions are identical, we only need one of them,
and we might as well give it a more descriptive name.  Basically,
the function serves as the translation from a QAPI name into a
(portion of a) C identifier, without regards to whether it is a
variable or function name.
Signed-off-by: NEric Blake <eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Now that we no longer have nested structs to visit, the use of
prefix strings is no longer required.  Remove the code that is
no longer reachable.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

A future patch will be using a 'name':{dictionary} entry in the
QAPI schema to specify a default value for an optional argument
(see previous commit messages for more details why); but existing
use of inline nested structs conflicts with that goal. Now that
all commands have been changed to avoid inline nested structs,
nuke support for them, and turn it into a hard error. Update the
testsuite to reflect tighter parsing rules.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Referring to "type" as both a meta-type (built-in, enum, union,
alternate, or struct) and a specific type (the name that the
schema uses for declaring structs) is confusing.  The confusion
is only made worse by the fact that the generator mostly already
refers to struct even when dealing with expr['type'].  This
commit changes the generator to consistently refer to it as
struct everywhere, plus a single back-compat tweak that allows
accepting the existing .json files as-is, so that the meat of
this change is separate from the mindless churn of that change.

Fix the testsuite fallout for error messages that change, and
in some cases, become more legible.  Improve comments to better
match our intentions where a struct (rather than any complex
type) is required.  Note that in some cases, an error message
now refers to 'struct' while the schema still refers to 'type';
that will be cleaned up in the later commit to the schema.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>

Previous patches have led up to the point where I create the
new meta-type "'alternate':'Foo'".  See the previous patches
for documentation; I intentionally split as much work into
earlier patches to minimize the size of this patch, but a lot
of it is churn due to testsuite fallout after updating to the
new type.
Signed-off-by: NEric Blake <eblake@redhat.com>
Reviewed-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>