C/C++ support

[fvgh]

I would like to provide C/C++ formatting support.
The following features shall be initially provided:

• C/C++ formatter based on CDT (see Provision of Spotless Eclipse CDT formatter plugin. #231)
• Include order changes based on existing code for ImportOrderStep
• Extension for Gradle/Maven whereas Maven will use default file name extensions and Gradle probably the native-specs (have to do some reading first...)

[fvgh]

I provided an example use case. Feedback is welcome.

[fvgh]

Formatting accomplished with #295.
Sorting of include statements still to be supported. Usage of ImportOrderStep is not a suitable option. CDT offers a highly configurable solution. Aiming to integrate CDT include-organizer.
Hence this issue remains open.

[fvgh]

The usage of IncludeOrganizer as it is provided by CDT is not an option.

• The amount of dependencies on other Eclipse components is quite high.
• Only a very small set of options is supported without pre-knowledge of the project setup (knowledge which headers belong to other libraries). Unfortunately even the header substitution is not applied.
• The results differ for the same configuration depending whether it is run with a project or without. This cannot be easily worked-around.

All in all it seems a better idea to implement an own organizer similar to the Spotless Java Import sorter.

[nedtwigg]

I try to keep the issues in-sync with our releases, but I missed this one! We have had C/C++ support since:

• plugin-maven 1.15.0 2018-09-23
• plugin-gradle 3.15.0 2018-09-23

It seems like a missing piece is an include organizer. One option is to build one from scratch, another would be to use clang-format (#475), and follow it up with eclipseCdt(). Regardless, even without include organizing, it's tremendously valuable to have Eclipse CDT's autoformatter included, thanks so much @fvgh! I'm going to close this as "long-ago implemented", and if you have a specific unmet need, feel free to open a new issue.

[nedtwigg]

As of plugin-gradle 5.2.0 we also support clang-format. PR for maven welcome :)