[for-4.0,v7,09/27] qapi: add 'if' to enum members

diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 610840d2e5..fdc0fd69ef 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -874,7 +874,8 @@  def check_enum(expr, info):
     for member in members:
         if isinstance(member, dict):
             source = "dictionary member of enum '%s'" % name
-            check_known_keys(info, source, member, ['name'], [])
+            check_known_keys(info, source, member, ['name'], ['if'])
+            check_if(member, info)
             member = member['name']
 
         check_name(info, "Member of enum '%s'" % name, member,
@@ -1358,9 +1359,10 @@  class QAPISchemaObjectType(QAPISchemaType):
 class QAPISchemaMember(object):
     role = 'member'
 
-    def __init__(self, name):
+    def __init__(self, name, ifcond=None):
         assert isinstance(name, str)
         self.name = name
+        self.ifcond = listify_cond(ifcond)
         self.owner = None
 
     def set_owner(self, name):
@@ -1672,9 +1674,11 @@  class QAPISchema(object):
         for v in values:
             if isinstance(v, dict):
                 name = v['name']
+                ifcond = v.get('if')
             else:
                 name = v
-            enum.append(QAPISchemaMember(name))
+                ifcond = None
+            enum.append(QAPISchemaMember(name, ifcond))
         return enum
 
     def _make_implicit_enum_type(self, name, info, ifcond, values):
diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
index 53eaf01f34..08c5ef97ff 100644
--- a/docs/devel/qapi-code-gen.txt
+++ b/docs/devel/qapi-code-gen.txt
@@ -752,6 +752,15 @@  gets its generated code guarded like this:
  #endif /* defined(HAVE_BAR) */
  #endif /* defined(CONFIG_FOO) */
 
+An enum value can be replaced by a dictionary with a 'name' and a 'if'
+key.
+
+Example: a conditional 'bar' enum member.
+
+{ 'enum': 'IfEnum', 'data':
+  [ 'foo',
+    { 'name' : 'bar', 'if': 'defined(IFCOND)' } ] }
+
 Please note that you are responsible to ensure that the C code will
 compile with an arbitrary combination of conditions, since the
 generators are unable to check it at this point.
diff --git a/tests/Makefile.include b/tests/Makefile.include
index 2e894c1037..3c9eea27fd 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -384,6 +384,7 @@  qapi-schema += enum-bad-name.json
 qapi-schema += enum-bad-prefix.json
 qapi-schema += enum-clash-member.json
 qapi-schema += enum-dict-member-unknown.json
+qapi-schema += enum-if-invalid.json
 qapi-schema += enum-int-member.json
 qapi-schema += enum-member-case.json
 qapi-schema += enum-missing-data.json
diff --git a/tests/qapi-schema/enum-dict-member-unknown.err b/tests/qapi-schema/enum-dict-member-unknown.err
index 76bd0471db..2aae618be0 100644
--- a/tests/qapi-schema/enum-dict-member-unknown.err
+++ b/tests/qapi-schema/enum-dict-member-unknown.err
@@ -1,2 +1,2 @@ 
 tests/qapi-schema/enum-dict-member-unknown.json:2: Unknown key 'bad-key' in dictionary member of enum 'MyEnum'
-Valid keys are 'name'.
+Valid keys are 'if', 'name'.
diff --git a/tests/qapi-schema/enum-if-invalid.err b/tests/qapi-schema/enum-if-invalid.err
new file mode 100644
index 0000000000..54c3cf887b
--- /dev/null
+++ b/tests/qapi-schema/enum-if-invalid.err
@@ -0,0 +1 @@ 
+tests/qapi-schema/enum-if-invalid.json:2: 'if' condition must be a string or a list of strings
diff --git a/tests/qapi-schema/enum-if-invalid.exit b/tests/qapi-schema/enum-if-invalid.exit
new file mode 100644
index 0000000000..d00491fd7e
--- /dev/null
+++ b/tests/qapi-schema/enum-if-invalid.exit
@@ -0,0 +1 @@ 
+1
diff --git a/tests/qapi-schema/enum-if-invalid.json b/tests/qapi-schema/enum-if-invalid.json
new file mode 100644
index 0000000000..60bd0ef1d7
--- /dev/null
+++ b/tests/qapi-schema/enum-if-invalid.json
@@ -0,0 +1,3 @@ 
+# check invalid 'if' type
+{ 'enum': 'TestIfEnum', 'data':
+  [ 'foo', { 'name' : 'bar', 'if': { 'val': 'foo' } } ] }
diff --git a/tests/qapi-schema/enum-if-invalid.out b/tests/qapi-schema/enum-if-invalid.out
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json
index fb03163430..22d9044a89 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -204,7 +204,8 @@ 
 { 'struct': 'TestIfStruct', 'data': { 'foo': 'int' },
   'if': 'defined(TEST_IF_STRUCT)' }
 
-{ 'enum': 'TestIfEnum', 'data': [ 'foo', 'bar' ],
+{ 'enum': 'TestIfEnum', 'data':
+  [ 'foo', { 'name' : 'bar', 'if': 'defined(TEST_IF_ENUM_BAR)' } ],
   'if': 'defined(TEST_IF_ENUM)' }
 
 { 'union': 'TestIfUnion', 'data': { 'foo': 'TestStruct' },
@@ -213,7 +214,7 @@ 
 { 'alternate': 'TestIfAlternate', 'data': { 'foo': 'int', 'bar': 'TestStruct' },
   'if': 'defined(TEST_IF_ALT) && defined(TEST_IF_STRUCT)' }
 
-{ 'command': 'TestIfCmd', 'data': { 'foo': 'TestIfStruct' },
+{ 'command': 'TestIfCmd', 'data': { 'foo': 'TestIfStruct', 'bar': 'TestIfEnum' },
   'returns': 'UserDefThree',
   'if': ['defined(TEST_IF_CMD)', 'defined(TEST_IF_STRUCT)'] }
 
diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out
index 39cd2b0fc3..130199fe8f 100644
--- a/tests/qapi-schema/qapi-schema-test.out
+++ b/tests/qapi-schema/qapi-schema-test.out
@@ -272,6 +272,7 @@  object TestIfStruct
 enum TestIfEnum
     member foo
     member bar
+        if ['defined(TEST_IF_ENUM_BAR)']
     if ['defined(TEST_IF_ENUM)']
 object q_obj_TestStruct-wrapper
     member data: TestStruct optional=False
@@ -290,6 +291,7 @@  alternate TestIfAlternate
     if ['defined(TEST_IF_ALT) && defined(TEST_IF_STRUCT)']
 object q_obj_TestIfCmd-arg
     member foo: TestIfStruct optional=False
+    member bar: TestIfEnum optional=False
     if ['defined(TEST_IF_CMD)', 'defined(TEST_IF_STRUCT)']
 command TestIfCmd q_obj_TestIfCmd-arg -> UserDefThree
    gen=True success_response=True boxed=False oob=False preconfig=False
diff --git a/tests/qapi-schema/test-qapi.py b/tests/qapi-schema/test-qapi.py
index 641a18f06d..aadf252d9d 100644
--- a/tests/qapi-schema/test-qapi.py
+++ b/tests/qapi-schema/test-qapi.py
@@ -29,6 +29,7 @@  class QAPISchemaTestVisitor(QAPISchemaVisitor):
             print('    prefix %s' % prefix)
         for m in members:
             print('    member %s' % m.name)
+            self._print_if(m.ifcond, indent=8)
         self._print_if(ifcond)
 
     def visit_object_type(self, name, info, ifcond, base, members, variants):