cpp-edit-list

cpp-edit-list is a variable defined in `cpp.el'.
Its value is

nil

Documentation:
Alist of cpp macros and information about how they should be displayed.
Each entry is a list with the following elements:
0. The name of the macro (a string).
1. Face used for text that is `ifdef' the macro.
2. Face used for text that is `ifndef' the macro.
3. t, nil, or `both' depending on what text may be edited.

You can customize this variable.