Makefile ifeq: when are they evaluated?

Question

The following is a very simple makefile that does not seem to work properly.

TEST=ON

buildbegin:
ifeq ($(TEST),ON)        
    @echo TEST PASSED
else
    @echo TEST FAILED
endif

No matter what I set the TEST variable to, my ifeq statement passes. I always see TEST PASSED. Anyone see what I am doing wrong here?

EDIT:

ok. my example was not exactly accurate. What I actually have is this:

SHELL = /bin/sh

DEFAULT_TARGS:= all  all_debug  
DEBUG_TARGS:= all_debug
ALL_TARGS:= $(DEFAULT_TARGS) $(DEBUG_TARGS)

.PHONY: $(ALL_TARGS)
.PHONY: buildbegin

$(ALL_TARGS): buildbegin

TEST=ON

$(DEBUG_TARGS): TEST=OFF

buildbegin:
    @echo $(TEST)
ifeq ($(TEST),ON)
    @echo PASSED
else
    @echo FAILED
endif

Running either make all or make all_debug will result in "PASSED" being printed. If I echo $(TEST) before the condition, it looks as if my rules are changing the variable, but the ifeq only ever sees whatever the default value is.

Answer 1

make evaluates conditionals when it reads a makefile (as you know it uses 2 passes), see: Conditional Parts of Makefiles. You can simply check this by using warning (which is good thing to debug makefiles):

buildbegin:
    @echo $(TEST)
$(warning now we reached ifeq TEST=$(TEST))
ifeq ($(TEST),ON)
    @echo PASSED
else
    @echo FAILED
endif

You should use shell commands instead and include them in rule:

buildbegin:
      @if [ "$(TEST)" = "ON" ]; then echo "PASSED"; else echo "FAILED"; fi