Values for define_macros=

[mdavidsaver]

For Extension(defines_macros=[...], ...) the defines_macros list is documented as accepting entries of the form ('NAME','value') and ('NAME',None), which with GCC yield -DNAME=value and -DNAME respectively. I find that a third form ('NAME',) is accepted, yielding -UNAME.

This third form is redundant to the undef_macros=[...] list, with the added benefit of control over relative ordering, which is important as I have a situation where I want to pass -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 in this order to override the default value of that builtin macro.

Is this third form considered supported? If not, can it be?