qapi: Improve reporting of invalid flags

Split check_flags() off check_keys() and have check_exprs() call it
later, so its error messages gain an "in definition" line.  Tweak the
error messages.

Checking values in a function named check_keys() is unclean anyway.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190927134639.4284-20-armbru@redhat.com>

scripts/qapi/common.py

@@ -915,16 +915,17 @@ def check_keys(expr, info, meta, required, optional=[]):
     required = required + [meta]
     source = "%s '%s'" % (meta, name)
     check_known_keys(expr, info, source, required, optional)
-    for (key, value) in expr.items():
-        if key in ['gen', 'success-response'] and value is not False:
-            raise QAPISemError(info,
-                               "'%s' of %s '%s' should only use false value"
-                               % (key, meta, name))
-        if (key in ['boxed', 'allow-oob', 'allow-preconfig']
-                and value is not True):
-            raise QAPISemError(info,
-                               "'%s' of %s '%s' should only use true value"
-                               % (key, meta, name))
+
+
+def check_flags(expr, info):
+    for key in ['gen', 'success-response']:
+        if key in expr and expr[key] is not False:
+            raise QAPISemError(
+                info, "flag '%s' may only use false value" % key)
+    for key in ['boxed', 'allow-oob', 'allow-preconfig']:
+        if key in expr and expr[key] is not True:
+            raise QAPISemError(
+                info, "flag '%s' may only use true value" % key)
 
 
 def normalize_enum(expr):
@@ -1027,6 +1028,7 @@ def check_exprs(exprs):
             assert False, 'unexpected meta type'
 
         check_if(expr, info)
+        check_flags(expr, info)
 
         if doc:
             doc.check_expr(expr)

tests/qapi-schema/allow-preconfig-test.err

@@ -1 +1,2 @@
-tests/qapi-schema/allow-preconfig-test.json:2: 'allow-preconfig' of command 'allow-preconfig-test' should only use true value
+tests/qapi-schema/allow-preconfig-test.json: In command 'allow-preconfig-test':
+tests/qapi-schema/allow-preconfig-test.json:2: flag 'allow-preconfig' may only use true value

tests/qapi-schema/args-bad-boxed.err

@@ -1 +1,2 @@
-tests/qapi-schema/args-bad-boxed.json:2: 'boxed' of command 'foo' should only use true value
+tests/qapi-schema/args-bad-boxed.json: In command 'foo':
+tests/qapi-schema/args-bad-boxed.json:2: flag 'boxed' may only use true value

tests/qapi-schema/oob-test.err

@@ -1 +1,2 @@
-tests/qapi-schema/oob-test.json:2: 'allow-oob' of command 'oob-command-1' should only use true value
+tests/qapi-schema/oob-test.json: In command 'oob-command-1':
+tests/qapi-schema/oob-test.json:2: flag 'allow-oob' may only use true value

tests/qapi-schema/type-bypass-bad-gen.err

@@ -1 +1,2 @@
-tests/qapi-schema/type-bypass-bad-gen.json:2: 'gen' of command 'foo' should only use false value
+tests/qapi-schema/type-bypass-bad-gen.json: In command 'foo':
+tests/qapi-schema/type-bypass-bad-gen.json:2: flag 'gen' may only use false value