Log wrapper in makefile? - makefile

Question

I m trying to write a simple log wrapper in makefile as shown below
define do_log
ifeq ($(1),1)
$(info ---------- $(shell date +%H:%M:%S) $(2))
else ifeq ($(1),2)
$(warning ^^^^^^^^^^ $(shell date +%H:%M:%S) $(2))
else ifeq ($(1),3)
$(error !!!!!!!!!! $(shell date +%H:%M:%S) $(2))
endif
endef
But every-time i call this function
$(call do_log,1,"hello")
All statements are getting executed
$ make
---------- 18:22:45 "hello"
Makefile:16: ^^^^^^^^^^ 18:22:45 "hello"
Makefile:16: *** !!!!!!!!!! 18:22:45 "hello". Stop.
Can someone please help me understand, on what am i doing wrong ?

Answer 1

ifeq etc. are more like preprocessor statements. They are only meaningful to make's makefile parser. They have no special meaning or significance to variable expansion etc., just like how you can't use C/C++ preprocessor statements at runtime.
The behavior you see is because call first expands the variable, and when that happens only variables are considered. This means that call sees something like this:
<text> $(1) <text>
$(info ---------- $(shell date +%H:%M:%S) $(2))
<text> $(1) <text>
$(warning ^^^^^^^^^^ $(shell date +%H:%M:%S) $(2))
<text> $(1) <text>
$(error !!!!!!!!!! $(shell date +%H:%M:%S) $(2))
<text>
and all those variable/function references are expanded. In general you cannot use ifeq etc. in a define variable unless you expect to use it with eval (which parses its string using the makefile parser).
Since you've not really shown us how you want to use this it's hard to suggest The best alternative, but to literally translate what you're doing here you could use:
define do_log
$(if $(filter-out 1,$(1)),,$(info ---------- $(shell date +%H:%M:%S) $(2)))
$(if $(filter-out 2,$(1)),,$(warning ^^^^^^^^^^ $(shell date +%H:%M:%S) $(2)))
$(if $(filter-out 3,$(1)),,$(error !!!!!!!!!! $(shell date +%H:%M:%S) $(2)))
endef

Answer 2

This can be achieved with eval :
define do_log
ifeq ($(1),1)
$$(info ---------- $(shell date +%H:%M:%S) $(2))
else ifeq ($(1),2)
$$(warning ^^^^^^^^^^ $(shell date +%H:%M:%S) $(2))
else ifeq ($(1),3)
$$(error !!!!!!!!!! $(shell date +%H:%M:%S) $(2))
endif
endef
$(eval $(call do_log,3,"hello"))