4.3.37 -XCC=a

Accepts C++-style comments. In particular, // can be used to indicate the start of a comment. a can be either yes or no. The default is -XCC=no. Specifying -XCC is equivalent to specifying -XCC=yes.

You only need to use this option if you use -xc99=none. Under -xc99=all (the default), lint accepts comments which are indicated by //.