We don't actually check, so the user can get some unpleasant stacktraces.
Formalize it.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 scripts/qapi/expr.py                              | 7 +++++++
 tests/qapi-schema/alternate-invalid-data-type.err | 2 ++
 tests/qapi-schema/union-invalid-data-type.err     | 2 ++
 3 files changed, 11 insertions(+)

diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
index 73e7d8cb0d..ca5ab7bfda 100644
--- a/scripts/qapi/expr.py
+++ b/scripts/qapi/expr.py
@@ -281,6 +281,9 @@ def check_union(expr, info):
             raise QAPISemError(info, "'discriminator' requires 'base'")
         check_name_is_str(discriminator, info, "'discriminator'")
 
+    if not isinstance(members, dict):
+        raise QAPISemError(info, "'data' must be an object")
+
     for (key, value) in members.items():
         source = "'data' member '%s'" % key
         if discriminator is None:
@@ -296,6 +299,10 @@ def check_alternate(expr, info):
 
     if not members:
         raise QAPISemError(info, "'data' must not be empty")
+
+    if not isinstance(members, dict):
+        raise QAPISemError(info, "'data' must be an object")
+
     for (key, value) in members.items():
         source = "'data' member '%s'" % key
         check_name_lower(key, info, source)
diff --git a/tests/qapi-schema/alternate-invalid-data-type.err b/tests/qapi-schema/alternate-invalid-data-type.err
index e69de29bb2..c7301ccb00 100644
--- a/tests/qapi-schema/alternate-invalid-data-type.err
+++ b/tests/qapi-schema/alternate-invalid-data-type.err
@@ -0,0 +1,2 @@
+alternate-invalid-data-type.json: In alternate 'Alt':
+alternate-invalid-data-type.json:2: 'data' must be an object
diff --git a/tests/qapi-schema/union-invalid-data-type.err b/tests/qapi-schema/union-invalid-data-type.err
index e69de29bb2..b71c3400c5 100644
--- a/tests/qapi-schema/union-invalid-data-type.err
+++ b/tests/qapi-schema/union-invalid-data-type.err
@@ -0,0 +1,2 @@
+union-invalid-data-type.json: In union 'TestUnion':
+union-invalid-data-type.json:9: 'data' must be an object
-- 
2.30.2

Suggest

    qapi/expr.py: Check type of union and alternate 'data' member

John Snow <jsnow@redhat.com> writes:

> We don't actually check, so the user can get some unpleasant stacktraces.

Let's point to the new tests here.

> Formalize it.

Huh?

> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  scripts/qapi/expr.py                              | 7 +++++++
>  tests/qapi-schema/alternate-invalid-data-type.err | 2 ++
>  tests/qapi-schema/union-invalid-data-type.err     | 2 ++
>  3 files changed, 11 insertions(+)
>
> diff --git a/scripts/qapi/expr.py b/scripts/qapi/expr.py
> index 73e7d8cb0d..ca5ab7bfda 100644
> --- a/scripts/qapi/expr.py
> +++ b/scripts/qapi/expr.py
> @@ -281,6 +281,9 @@ def check_union(expr, info):
>              raise QAPISemError(info, "'discriminator' requires 'base'")
>          check_name_is_str(discriminator, info, "'discriminator'")
>  
> +    if not isinstance(members, dict):
> +        raise QAPISemError(info, "'data' must be an object")
> +
>      for (key, value) in members.items():
>          source = "'data' member '%s'" % key
>          if discriminator is None:
> @@ -296,6 +299,10 @@ def check_alternate(expr, info):
>  
>      if not members:
>          raise QAPISemError(info, "'data' must not be empty")
> +
> +    if not isinstance(members, dict):
> +        raise QAPISemError(info, "'data' must be an object")
> +
>      for (key, value) in members.items():
>          source = "'data' member '%s'" % key
>          check_name_lower(key, info, source)
> diff --git a/tests/qapi-schema/alternate-invalid-data-type.err b/tests/qapi-schema/alternate-invalid-data-type.err
> index e69de29bb2..c7301ccb00 100644
> --- a/tests/qapi-schema/alternate-invalid-data-type.err
> +++ b/tests/qapi-schema/alternate-invalid-data-type.err
> @@ -0,0 +1,2 @@
> +alternate-invalid-data-type.json: In alternate 'Alt':
> +alternate-invalid-data-type.json:2: 'data' must be an object
> diff --git a/tests/qapi-schema/union-invalid-data-type.err b/tests/qapi-schema/union-invalid-data-type.err
> index e69de29bb2..b71c3400c5 100644
> --- a/tests/qapi-schema/union-invalid-data-type.err
> +++ b/tests/qapi-schema/union-invalid-data-type.err
> @@ -0,0 +1,2 @@
> +union-invalid-data-type.json: In union 'TestUnion':
> +union-invalid-data-type.json:9: 'data' must be an object

On 3/25/21 10:26 AM, Markus Armbruster wrote:
> Suggest
> 
>      qapi/expr.py: Check type of union and alternate 'data' member
> 
> John Snow <jsnow@redhat.com> writes:
> 
>> We don't actually check, so the user can get some unpleasant stacktraces.
> 
> Let's point to the new tests here.
> 

Well, it'll get merged with the last one to keep make check working, so 
I have to update the commit message anyway.