Consider narrowing the scope of #undef ERROR in generated message code

[gerkey]

d4264b7#commitcomment-17146232

[mikaelarguedas]

This is a known problem that we face is ROS1 as well (e.g. ros/geometry2#172) and it would be great to see how we can address these collisions with Windows defined in the near future

[dejanpan]

This issue has come up again here:

The generated file build\tf2_msgs\rosidl_generator_cpp\tf2_msgs\msg\tf2_error__struct.hpp contains the following code that conflicts with Windows' definition:

  // constants
  enum { NO_ERROR = 0u };

Windows SDK defines macro NO_ERROR in Error.h:

#define NO_ERROR            0

We have confirmed for myself that that culprit is Windows SDK. On a clean installation everything works OK but as soon as we installed Windows SDK the build fails in TF2 (now it fails in Release build too).

@wjwwood says:
It might also be possible to change these constants in ROS 2 (with appropriate special handling in the ros1_bridge).

[tfoote]

This is also an issue with 'DELETE' defined in winnt.h: ros2/common_interfaces#44

We'll either need some way to generically protect ourselves from some known set of conflicting strings or else have a blacklist of known strings that must be banned due to windows bad hygene in macro names.

Might it make sense to have a known set of potentially colliding macros that automatically get undefed in our code generators if a conflict is detected?

[dirk-thomas]

Options:

• undefine Windows specific MACRO (preferrably only when the message actually uses that name)
• name mangle the enum (e.g. appending an underscore)
• use different enum naming scheme (e.g. kError)

[tfoote]

Related: ros2/design#172