Disable make builtin rules and variables from inside the make file

Question

I want to disable builtin rules and variables as per passing the -r and -R options to GNU make, from inside the make file. Other solutions that allow me to do this implicitly and transparently are also welcome.

I've found several references to using MAKEFLAGS, and had similar problems.

Answer 1

Disabling the built-in rules is done by writing an empty rule for .SUFFIXES:

.SUFFIXES:

Having erased the built-in rules, I'm not sure that erasing the built-in variables helps you much more than just remembering to set them yourself or not use them, but you could use something like

$(foreach V
    $(shell make -p -f/dev/null 2>/dev/null | sed -n '/^[^:#= ]* *=/s/ .*//p'),
    $(if $(findstring default,$(origin $V)),$(eval $V=)))

...which is admittedly fairly crazy. If there is a way to get a list of the defined variables from within make (instead of shelling out to another make), it would be viable. As it is, it's not really much better than

CC=
CXX=
# etc, for each likely built-in variable