Add support for custom defines

[qistoph]

Could you consider adding support for custom defines, so that something like the example below would work? Or am I overlooking an available approach to make this work?

#ifdef ALTERNATIVE_V1
  void specialCall() {
    // Runs alternative code
  }
#else
  void specialCall() {
    // Runs standard code
  }
#endif

$ make CUSTOM_DEFINES="-DALTERNATIVE_V1"

[tuna-f1sh]

You should be able to pass custom defines as part of the compiler flags since they are appended in the Makefile rather than set - I've done it this way before.

For .cpp and .c source you can use CPPFLAGS="-D..." or CXXFLAGS='"-D...". .c source only uses CFLAGS="-D..."

[qistoph]

Thanks for your feedback. Somehow using CXXFLAGS does work, where CPPFLAGS doesn't. So it seems my issue is solvable.

Using CPPFLAGS

$ cat Makefile 
# Arduino Make file. Refer to https://github.com/sudar/Arduino-Makefile
BOARD_TAG   = nano
BOARD_SUB   = atmega328
ARDUINO_DIR  = /home/chris/arduino-1.8.5/
include /home/chris/Projects/Arduino-Makefile/Arduino.mk

alt1:
	$(MAKE) CPPFLAGS="-DALT1" OBJDIR=build-alt1-$(BOARD_TAG)-$(BOARD_SUB)

$ make alt1
...
make CPPFLAGS="-DALT1" OBJDIR=build-alt1-nano-atmega328
make[1]: Entering directory '/home/chris/Projects/Test'
mkdir -p build-alt1-nano-atmega328
/home/chris/arduino-1.8.5//hardware/tools/avr/bin/avr-g++ -x c++ -include Arduino.h -MMD -c -DALT1 -fpermissive -fno-exceptions -std=gnu++11 -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color=always Test.ino -o build-alt1-nano-atmega328/Test.ino.o
cc1plus: fatal error: Arduino.h: No such file or directory
compilation terminated.
/home/chris/Projects/Arduino-Makefile/Arduino.mk:1314: recipe for target 'build-alt1-nano-atmega328/Test.ino.o' failed

Using CXXFLAGS

$ cat Makefile 
# Arduino Make file. Refer to https://github.com/sudar/Arduino-Makefile
BOARD_TAG   = nano
BOARD_SUB   = atmega328
ARDUINO_DIR  = /home/chris/arduino-1.8.5/
include /home/chris/Projects/Arduino-Makefile/Arduino.mk

alt1:
	$(MAKE) CXXFLAGS="-DALT1" OBJDIR=build-alt1-$(BOARD_TAG)-$(BOARD_SUB)

$ make alt1
...
make CXXFLAGS="-DALT1" OBJDIR=build-alt1-nano-atmega328
make[1]: Entering directory '/home/chris/Projects/Test'
mkdir -p build-alt1-nano-atmega328
/home/chris/arduino-1.8.5//hardware/tools/avr/bin/avr-g++ -x c++ -include Arduino.h -MMD -c -D__PROG_TYPES_COMPAT__ -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=185 -DARDUINO_ARCH_AVR -I/home/chris/arduino-1.8.5//hardware/arduino/avr/cores/arduino -I/home/chris/arduino-1.8.5//hardware/arduino/avr/variants/eightanaloginputs    -Wall -ffunction-sections -fdata-sections -Os -DALT1 Test.ino -o build-alt1-nano-atmega328/Test.ino.o

[tuna-f1sh]

Yes I'm not sure why but setting CPPFLAGS external to the Arduino.mk seems to drop all the include flags, despite it being appended here: https://github.com/sudar/Arduino-Makefile/blob/master/Arduino.mk#L1062

Not got time to look into it now but maybe you can spot something. I thought it might be this line doing the expand prior to the includes but commenting it out still presents the same problem.

[qistoph]

Just found out that using CXXFLAGS does influence the build. The following arguments are missing when using CXXFLAGS from my Makefile:

-fpermissive -fno-exceptions -std=gnu++11 -f| braries/Servo/src -I/home/chris/arduino-1.8.5//hardware/arduino/avr/libraries/EEPROM/src -Wall -ffun no-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color=always

I think the variables that are passed as arguments are not overwritten or appended from the Arduino.mk. I think this thread is explaining a possible solution. I'm going to give it a try...

[qistoph]

Jup, that seems to make it work. Updated the PR to reflect this :)

Thanks for your help in figuring it out and make the solution much cleaner.

[qistoph]

Just checking up if you are going to merge this into master?
I am referring Arduino-Makefile in one of my projects that I'm going to share with some friends. If they could just use the default Arduino-Makefile, that would be much easier for them.

[tuna-f1sh]

I can't merge as I'm a contributor not collaborator. If you want more chance of getting it merge though, it would be worth updating the arduino-vars.md and changelog as described in CONTRIBUTING.MD.

There might be something to be said for sticking to the original sole addition of a variable, in case people are using the passing of CPPFLAGS in the command args to override the default intentionally.

[sudar]

@qistoph

Thanks for the PR. Please do add some documentation in the arduino-vars.md file.

[wingunder]

I patched the current master's HEAD, fe84c59, examples/Blink/Blink.ino with the following patch:
https://gist.github.com/6d223de494e7f5a57a3392b21e819986

I then ran the following in the examples/Blink directory:

$ CPPFLAGS="-DALTERNATIVE_V1 -DUSING_CPPFLAGS" make clean all 2>&1 |grep Blink.ino
/usr/share/arduino/hardware/tools/avr/bin/avr-g++ -x c++ -include Arduino.h -MMD -c -D__PROG_TYPES_COMPAT__ -DALTERNATIVE_V1 -DUSING_CPPFLAGS -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=105  -I/usr/share/arduino/hardware/arduino//cores/arduino -I/usr/share/arduino/hardware/arduino//variants/standard    -Wall -ffunction-sections -fdata-sections -Os -fpermissive -fno-exceptions -std=gnu++11 -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color=always Blink.ino -o build-uno/Blink.ino.o
Blink.ino:9:2: warning: #warning "Yes, ALTERNATIVE_V1 was assigned!" [-Wcpp]
/usr/share/arduino/hardware/tools/avr/bin/avr-gcc -mmcu=atmega328p -Wl,--gc-sections -Os -flto -fuse-linker-plugin -o build-uno/Blink.elf build-uno/Blink.ino.o build-uno/libcore.a   -lc -lm 

So, using CPPFLAGS works for me.

$ CXXFLAGS="-DALTERNATIVE_V1 -DUSING_CXXFLAGS" make clean all 2>&1 |grep Blink.ino
/usr/share/arduino/hardware/tools/avr/bin/avr-g++ -x c++ -include Arduino.h -MMD -c -D__PROG_TYPES_COMPAT__ -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=105  -I/usr/share/arduino/hardware/arduino//cores/arduino -I/usr/share/arduino/hardware/arduino//variants/standard    -Wall -ffunction-sections -fdata-sections -Os -DALTERNATIVE_V1 -DUSING_CXXFLAGS -fpermissive -fno-exceptions -std=gnu++11 -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color=always Blink.ino -o build-uno/Blink.ino.o
Blink.ino:9:2: warning: #warning "Yes, ALTERNATIVE_V1 was assigned!" [-Wcpp]
/usr/share/arduino/hardware/tools/avr/bin/avr-gcc -mmcu=atmega328p -Wl,--gc-sections -Os -flto -fuse-linker-plugin -o build-uno/Blink.elf build-uno/Blink.ino.o   build-uno/libcore.a -lc -lm 

And using CXXFLAGS also work for me.

$ DUFF_FLAGS="-DALTERNATIVE_V1 -DUSING_DUFF_FLAGS" make clean all 2>&1 |grep Blink.ino
/usr/share/arduino/hardware/tools/avr/bin/avr-g++ -x c++ -include Arduino.h -MMD -c -D__PROG_TYPES_COMPAT__ -mmcu=atmega328p -DF_CPU=16000000L -DARDUINO=105  -I/usr/share/arduino/hardware/arduino//cores/arduino -I/usr/share/arduino/hardware/arduino//variants/standard    -Wall -ffunction-sections -fdata-sections -Os -fpermissive -fno-exceptions -std=gnu++11 -fno-threadsafe-statics -flto -fno-devirtualize -fdiagnostics-color=always Blink.ino -o build-uno/Blink.ino.o
Blink.ino:11:2: error: #error "No, ALTERNATIVE_V1 was NOT assigned!"
make: *** [../../Arduino.mk:1311: build-uno/Blink.ino.o] Error 1

And finally, as expected, not setting either CPPFLAGS or CXXFLAGS doesn't work.

Maybe I'm missing something here. If not, I think CPPFLAGS or CXXFLAGS could be used as I demonstrated above and there is really no need for CUSTOM_DEFINES.

I think that the override directive was not used correctly in this patch, as:
From https://www.gnu.org/software/make/manual/html_node/Override-Directive.html:

If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive,

The way I understand it, we're always extending (prepending to, using :=, or appending to, using +=) CXXFLAGS/CPPFLAGS. We never override them (using =). Or do we want to override them? If so, overriding should from my point of view be in a separate patch, as it has nothing to do with the pure appending of CUSTOM_DEFINES to CPPFLAGS.

If we want it and if I'm not completely missing the point, adding CUSTOM_DEFINES should be as simple as adding the following to Arduino.mk, before the first usage of $(CPPFLAGS):

ifdef CUSTOM_DEFINES
    CPPFLAGS += $(CUSTOM_DEFINES)
endif