Both the IDL struct and bitset support inheritance in 6.31, at the moment the struct/bitset has a base, a IDL::traits<>::base_type should be make available for template meta programming

Proposal is to add a @cpp_mapping as IDL4toC++ has, to enable users to select a mapping of IDL struct to a C++ struct (that mapping itself has to be added here also)

In user code I want to use constexpr for IDL fixed values, for example

constexr F pi

;

But in order for that to work a constexpr constructor has to be available, the spec should define that

CORBA::CustomerMarshal, should be CORBA::CustomMarshal,

CORBA::CustomerMarshal should be CORBA::CustomMarshal

In order to get a type system which is CORBA independent we propose to change the exception which can be thrown by the union from CORBA::BAD_PARAM to std::invalid_argument. The impact for users is minimal as they can except std exceptions from the other std types they already use through this language mapping.

The specification lacks a description how to map the @external annotation

The IDL to C++11 spec lacks a mapping for the min/max/range annotations

The spec says "In case the union has an implicit default member it is initialized to that case", but it doesn't specify what is an implicit default member, maybe add "i.e., if the union does not have a default case and not all permissive discriminator values are listed"

The default annotation is not just for struct members, also for exception/union members but it can also be applied to a type, so also for example attributes of an interface/component/connector can have a default, all code generation related to that should also use the default whenever one is needed (for example starter code generation)

All IDL/C++ that is used in the text should be have a different font like done in the other parts of the spec, that is for example int8_t/uint8_t/Base::Base/

There shouldn't be a semi colon after the namespace closure, this is done in more places in the spec, search for "namespace", closing should be "}" and not "};", see chapters 6.3/6.5/6.23.1/6.26.2/6.27.2/6.28/6.29

For the following places the declared destructors should be using override and not virtual as they override the base class destructor. This should happen to:

• 6.18.4, see "virtual ~Example();"
• 6.18.4, see "virtual ~OBV_Example();"
• 6.20, see "virtual ~Exception();"
• 6.20, see "virtual ~SystemException();"
• 6.25, see "virtual ~MyLocalIF();"
• 6.26.6, see "virtual ~A_skel ();" and "virtual ~A_impl ();"
• 6.26.8 see "virtual ~TIE() = default;"

For the optional mapping example a `void age(IDL::optional<float>&&)` is lacking, like described for some types in chapter 6.14

For the example code, for the setter, the std::optional should be passed as const&, see https://stackoverflow.com/questions/69277649/does-passing-an-stdoptionalt-by-reference-actually-save-copying

Within the text of chapter 6.31/6.32 (IDL4) all C++/IDL should use a different font to make it clear it is code, just as in the other chapters.

For anyone using the class mapping of a structure the spec should also provide a class mapping for a bitset, that way they have a consistent API. Also why is a inherited bitset not mapped to C++ inheritance, by removing the inheritance the inheritance relation can't be used in C++ also

C++20 modules look very interesting for sharing declarations/definitions based on IDL (see https://en.cppreference.com/w/cpp/language/modules), would be good when this spec has support for C++20 modules