qapi: Command returning anonymous type doesn't work, outlaw

Reproducer: with

    { 'command': 'user_def_cmd4', 'returns': { 'a': 'int' } }

added to qapi-schema-test.json, qapi-commands.py dies when it tries to
generate the command handler function

    Traceback (most recent call last):
      File "/work/armbru/qemu/scripts/qapi-commands.py", line 359, in <module>
        ret = generate_command_decl(cmd['command'], arglist, ret_type) + "\n"
      File "/work/armbru/qemu/scripts/qapi-commands.py", line 29, in generate_command_decl
        ret_type=c_type(ret_type), name=c_name(name),
      File "/work/armbru/qemu/scripts/qapi.py", line 927, in c_type
        assert isinstance(value, str) and value != ""
    AssertionError

because the return type doesn't exist.

Simply outlaw this usage, and drop or dumb down test cases accordingly.

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

1 files changed, 8 insertions, 9 deletions

diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index c19c15732d..a253e27d5f 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -394,7 +394,7 @@ following example objects:
 === Commands ===
 
 Usage: { 'command': STRING, '*data': COMPLEX-TYPE-NAME-OR-DICT,
-         '*returns': TYPE-NAME-OR-DICT,
+         '*returns': TYPE-NAME,
          '*gen': false, '*success-response': false }
 
 Commands are defined by using a dictionary containing several members,
@@ -415,14 +415,13 @@ The member is optional from the command declaration; if absent, the
 "return" field will be an empty dictionary.  If 'returns' is present,
 it must be the string name of a complex or built-in type, a
 one-element array containing the name of a complex or built-in type,
-or a dictionary that declares an anonymous type with the same
-semantics as a 'struct' expression, with one exception noted below
-when 'gen' is used.  Although it is permitted to have the 'returns'
-member name a built-in type or an array of built-in types, any command
-that does this cannot be extended to return additional information in
-the future; thus, new commands should strongly consider returning a
-dictionary-based type or an array of dictionaries, even if the
-dictionary only contains one field at the present.
+with one exception noted below when 'gen' is used.  Although it is
+permitted to have the 'returns' member name a built-in type or an
+array of built-in types, any command that does this cannot be extended
+to return additional information in the future; thus, new commands
+should strongly consider returning a dictionary-based type or an array
+of dictionaries, even if the dictionary only contains one field at the
+present.
 
 All commands in Client JSON Protocol use a dictionary to report
 failure, with no way to specify that in QAPI.  Where the error return