Implement unions as members of structs.

mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 {%- set header_guard = "%s_H_"|
         format(module.path|upper|replace("/","_")|replace(".","_")) %}
 
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
@@ skipping 45 matching lines @@
 {#--- Union Forward Declarations -#}
 {%  for union in unions %}
 class {{union.name}};
 {%    if union|should_inline_union %}
 typedef mojo::InlinedStructPtr<{{union.name}}> {{union.name}}Ptr;
 {%    else %}
 typedef mojo::StructPtr<{{union.name}}> {{union.name}}Ptr;
 {%    endif %}
 {%- endfor %}
 
+{#--- Unions must be declared first because they can be members of structs #}

[yzshen1, 2015/02/17 19:34:35]

Do we need to distinguish between "inlined unions" and "non-inlined unions" just
like what line 72 says for structs? (I haven't tried myself.)

[azani, 2015/02/18 00:27:57]

I don't think so. Unions are never inlined in unions, so that problem shouldn't
come up.

+{#--- Unions #}
+{%  for union in unions %}
+{%    include "wrapper_union_class_declaration.tmpl" %}
+{%- endfor %}
+
 {#--- NOTE: Non-inlined structs may have pointers to inlined structs, so we  #}
 {#---       need to fully define inlined structs ahead of the others.        #}
 
 {#--- Inlined structs #}
 {%  for struct in structs %}
 {%    if struct|should_inline %}
 {%      include "wrapper_class_declaration.tmpl" %}
 {%    endif %}
 {%- endfor %}
 
 {#--- Non-inlined structs #}
 {%  for struct in structs %}
 {%    if not struct|should_inline %}
 {%      include "wrapper_class_declaration.tmpl" %}
 {%    endif %}
 {%- endfor %}
 
-{#--- Unions #}
-{%  for union in unions %}
-{%    include "wrapper_union_class_declaration.tmpl" %}
-{%- endfor %}
-
 {#--- Interfaces -#}
 {%  for interface in interfaces %}
 {%    include "interface_declaration.tmpl" %}
 {%- endfor %}
 
 {#--- Interface Proxies -#}
 {%  for interface in interfaces %}
 {%    include "interface_proxy_declaration.tmpl" %}
 {%- endfor %}
 
@@ skipping 25 matching lines @@
 {%    for union in unions %}
 {{      serialization_macros.declare_serialization(union.name) }}
 {%-   endfor %}
 {%- endif %}
 
 {%- for namespace in namespaces_as_array|reverse %}
 }  // namespace {{namespace}}
 {%- endfor %}
 
 #endif  // {{header_guard}}