I am using a GNU Make Makefile to build a C project with several targets (all, clean, and a few project specific targets). In the process of debugging, I would like to append some flags to a single build without permanently editing the Makefile (e.g., add debugging symbols or set a preprocessor flag).
In the past, I have done that as follows (using the debugging symbols example):
make target CFLAGS+=-g
Unfortunately, this is not appending to the CFLAGS variable, but instead, clearing it and stopping it from compiling. Is there a clean way of doing this without defining some sort of dummy variable appended to the end of CFLAGS and LDFLAGS?
Check out the override directive. You will probably need to modify the makefile once, but it should do what you want.
Example makefile:
override CFLAGS += -Wall
app: main.c
gcc $(CFLAGS) -o app main.c
Example command lines:
$ make
gcc -Wall -o app main.c
$ make CFLAGS=-g
gcc -g -Wall -o app main.c