qapi: Prefix frontend errors with an "in definition" line

We take pains to include the offending expression in error messages,
e.g.

    tests/qapi-schema/alternate-any.json:2: alternate 'Alt' member 'one' cannot use type 'any'

But not always:

    tests/qapi-schema/enum-if-invalid.json:2: 'if' condition must be a string or a list of strings

Instead of improving them one by one, report the offending expression
whenever it is known, like this:

    tests/qapi-schema/enum-if-invalid.json: In enum 'TestIfEnum':
    tests/qapi-schema/enum-if-invalid.json:2: 'if' condition must be a string or a list of strings

Error messages that mention the offending expression become a bit
redundant, e.g.

    tests/qapi-schema/alternate-any.json: In alternate 'Alt':
    tests/qapi-schema/alternate-any.json:2: alternate 'Alt' member 'one' cannot use type 'any'

I'll take care of that later in this series.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190927134639.4284-5-armbru@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/qapi-schema/nested-struct-data.err b/tests/qapi-schema/nested-struct-data.err
index da767bade2..74d44ab111 100644
--- a/tests/qapi-schema/nested-struct-data.err
+++ b/tests/qapi-schema/nested-struct-data.err
@@ -1 +1,2 @@
+tests/qapi-schema/nested-struct-data.json: In command 'foo':
 tests/qapi-schema/nested-struct-data.json:2: Member 'a' of 'data' for command 'foo' should be a type name