Remove a flag from C++FLAGS in Makefile?

Question

I\'ve got a Makefile that includes another makefile that sets a lot of defaults. I can\'t edit the included makefile and I\'d like to change the value of C++FLAGS in my makefile

Answer 1

C++FLAGS:=$(filter-out -O3,$(C++FLAGS))

The := assignment immediately evaluates the rvalue and this should therefore work. = on the other hand has delayed expansion semantics (i.e. the C++FLAGS will expand whenever the lvalue gets used, which leads to recursion).