[Qemu-devel] [PULL 04/15] qapi: Forbid 'any' inside an alternate

[Markus Armbruster <armbru@redhat.com>]

From: Eric Blake <eblake@redhat.com>

The whole point of an alternate is to allow some type-safety while
still accepting more than one JSON type.  Meanwhile, the 'any'
type exists to bypass type-safety altogether.  The two are
incompatible: you can't accept every type, and still tell which
branch of the alternate to use for the parse; fix this to give a
sane error instead of a Python stack trace.

Note that other types that can't be alternate members are caught
earlier, by check_type().

Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <1455778109-6278-4-git-send-email-eblake@redhat.com>
[Commit message tweaked]
Signed-off-by: Markus Armbruster <armbru@redhat.com>
---
 scripts/qapi.py                      | 5 ++++-
 tests/Makefile                       | 1 +
 tests/qapi-schema/alternate-any.err  | 1 +
 tests/qapi-schema/alternate-any.exit | 1 +
 tests/qapi-schema/alternate-any.json | 4 ++++
 tests/qapi-schema/alternate-any.out  | 0
 6 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 tests/qapi-schema/alternate-any.err
 create mode 100644 tests/qapi-schema/alternate-any.exit
 create mode 100644 tests/qapi-schema/alternate-any.json
 create mode 100644 tests/qapi-schema/alternate-any.out

diff --git a/scripts/qapi.py b/scripts/qapi.py
index f97236f..17bf633 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -629,7 +629,10 @@ def check_alternate(expr, expr_info):
                    value,
                    allow_metas=['built-in', 'union', 'struct', 'enum'])
         qtype = find_alternate_member_qtype(value)
-        assert qtype
+        if not qtype:
+            raise QAPIExprError(expr_info,
+                                "Alternate '%s' member '%s' cannot use "
+                                "type '%s'" % (name, key, value))
         if qtype in types_seen:
             raise QAPIExprError(expr_info,
                                 "Alternate '%s' member '%s' can't "
diff --git a/tests/Makefile b/tests/Makefile
index c1c605f..7c66d16 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -241,6 +241,7 @@ check-qtest-xtensaeb-y = $(check-qtest-xtensa-y)
 
 check-qtest-generic-y += tests/qom-test$(EXESUF)
 
+qapi-schema += alternate-any.json
 qapi-schema += alternate-array.json
 qapi-schema += alternate-base.json
 qapi-schema += alternate-clash.json
diff --git a/tests/qapi-schema/alternate-any.err b/tests/qapi-schema/alternate-any.err
new file mode 100644
index 0000000..aaa0154
--- /dev/null
+++ b/tests/qapi-schema/alternate-any.err
@@ -0,0 +1 @@
+tests/qapi-schema/alternate-any.json:2: Alternate 'Alt' member 'one' cannot use type 'any'
diff --git a/tests/qapi-schema/alternate-any.exit b/tests/qapi-schema/alternate-any.exit
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/tests/qapi-schema/alternate-any.exit
@@ -0,0 +1 @@
+1
diff --git a/tests/qapi-schema/alternate-any.json b/tests/qapi-schema/alternate-any.json
new file mode 100644
index 0000000..e47a73a
--- /dev/null
+++ b/tests/qapi-schema/alternate-any.json
@@ -0,0 +1,4 @@
+# we do not allow the 'any' type as an alternate branch
+{ 'alternate': 'Alt',
+  'data': { 'one': 'any',
+            'two': 'int' } }
diff --git a/tests/qapi-schema/alternate-any.out b/tests/qapi-schema/alternate-any.out
new file mode 100644
index 0000000..e69de29
-- 
2.4.3