I guess with the menue item
it should be possible to deactive it.
That menu item gives me the option to disable auto-insertion of a lot of things, but not comment brackets, unfortunately. Not in my version anyway.
I'm not sure which eclipse version numbers to tell you about, but here is my guess:
Eclipse IDE for C/C++ Developers
I'm using Texas Instruments code composer studio 5.2.0.00069 which is Eclipse plus TI plug ins.
How would I install Eclipse alongside my TI installation to see whether the latest version of Eclipse now supports no auto adding of comment brackets, without risking the integrity of my existing installation?