Provide compile-time ROS2 version information

[serge-nikulin]

As ROS2 matures and introduces new API, we need ways to conditionally compile code against different, possibly compile-time incompatible, versions of ROS2.

Common ways to do it are:

• Define version macros or constants in C or C++ header file, e.g. (from FDRS code):

  #define FASTCDR_VERSION_MAJOR 1
  #define FASTCDR_VERSION_MINOR 0
  #define FASTCDR_VERSION_MICRO 9
  #define FASTCDR_VERSION_STR "1.0.9"

• Define version information in a CMake file and later generate a header file with C/C++ version macros or constants.

[dirk-thomas]

That sounds like a good idea. Please consider to contribute pull requests for packages where you see the need for it.

[serge-nikulin]

@dirk-thomas,

I can do a naive versioninig: plain C/C++ macros that should be upgraded manually before each build.

A "grownup", a right way to do versioning is to keep the last built version in some external DB and increment the minor version automatically and major/minor versions in a semi-auto way (via Jenkins commands?). This approach IMO should be implemented by ROS2 insiders who have full access to build infrastructure.

@dirk-thomas, should I go ahead with the naive approach pull request?

[dirk-thomas]

Each package already has the version number declared in the package.xml file which also gets bumped for every release. That value is available in CMake as <pkgname>_VERSION after the manifest file was parsed (that happens either in ament_package() or when ament_package_xml() is called any time earlier). So that information could be used for the macros which will need to be generated using configure_file().

[serge-nikulin]

@dirk-thomas, see #175

[aprotyas]

@clalancette how broad is this issue? rclcpp already generates a version header. Is there also a need for that in rcutils?

[clalancette]

@clalancette how broad is this issue? rclcpp already generates a version header. Is there also a need for that in rcutils?

I have no idea, honestly. Maybe @serge-nikulin can weigh in.

[serge-nikulin]

@aprotyas

@clalancette how broad is this issue? rclcpp already generates a version header. Is there also a need for that in rcutils?

This issue is very old. Back in 2019 ROS2 did not have any version information.
You can close this issue I guess.

Back then I wanted to generate version information for every generated library.
Rationale: in many shops, all files must have version information, and many safety and security standards require version tagging of every distributed file.

[clalancette]

Based on the previous comment, closing. Feel free to reopen if you change your mind and would like to continue.